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LCBS5059 Professional Field Experience
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LCBS5059 Professional Field Experience
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Course Code: LCBS5059
University: De Montfort University
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Country: United Kingdom
Question:
Topic:
Energy On-Demand a Major Challenge of Renewable Energy Source Going into the Green Energy Future.
Identify the major challenges and constraints to access renewable energy.
Answer:
Project: Problem Definition
The fossil fuels have been the cornerstone of the industrial revolution and have been able to provide energy on demand for the world for many decades. This is because the raw materials need for energy generation is readily available and could be used to produces energy quantities as required to meet demand. However, it effects on the climate and the environment coupled with the price changes on the international market for fossil fuels have led to expect to call for a change in the way we generate energy if we are to protect our environment. Yet, with the development of technologies that are available today and the cutting-edge technologies, alternative energy can now be accessible and developed. The concept of using renewable energy resources is therefore beneficial for reducing carbon footprints caused by emissions created by the consumption of fossil fuels. Irrespective of the availability of renewable sources of energy, the non-renewable energy sources are still considered a major source of energy (Elrayies, 2018). The present study is also aimed to demonstrate the benefits associated with the use of renewable energy sources and the barriers related to using of renewable energy sources.
This research aims to address issues related to promote the renewable energy sources for a sustainable future. The reason for emphasising this research is that the technology to utilise renewable energy has been available for a decade, but it has not been used at a greater extent to reduce the global carbon footprint. Although, the initiatives to ensure a sustainable future have been undertaken across the globe in developed countries. One of the examples is Sweden who is leading in the use of renewable energy across the world with countries like Costa Rica, Scotland in the UK, Germany, Denmark, Kenya, Morocco in Africa, China and USA who have taken steps for a greener future (O’Neill & Gibbs, 2018; Elrayies, 2018). Nevertheless, the access to clean and affordable energy is still out of hands for most of the world. According to Hosseini and Wahid (2016), the solar and water energy, which are major sources of alternative energy sources are extensive can be associated with some limitations. It is costly, complex and time-consuming to use the renewable energy phenomenon at a larger context, which can also be affected by weather condition. This may be due to different challenges related to production and utilisation of renewable energy sources. Thus, one of the problems that the research focuses is to identify the major challenges and constraints to access renewable energy on demand.
As the automobile industry has transformed the fuel consumption to renewable energy including hybrid vehicles, solar vehicles and electronic vehicles (Hannan, Azidin &Mohamed, 2014); the access to renewable energy in households and premises have also been constrained. Although, the concepts of zero-emission houses in the UK and Passivhaus in Germany have been realised they have not been promoted at a broad level to reduce the carbon footprint (Kylili &Fokaides, 2015). Similarly, the low-energy consuming homes in Switzerland have also been observed as Minergie that also uses the similar concept of passive houses (Panos and Kannan, 2016). The design of the electronics component and energy consuming equipment must be such that they are designed to consume less energy. In this way, the world would be able to address the energy consumption in our homes and public places, which can go a long way in achieving a set desire for a green energy future. Another problem is the limited knowledge among the population pertaining to houses that consume less energy. Therefore, another problem to explore in this study is the role of renewable homes in reducing the carbon emissions and the need for people to understand that renewable energy cannot be used the way we use energy from fossil fuel. An additional problem to study is suggesting the ways at a wider level to promote the use of renewable energy by the local population for a greener future.
Addressing Research Problem
There are three research problems that have been identified above and they would be addressed in this research.
The first research problem is to describe the critical review of the renewable and non-renewable energy resources by considering different forms of renewable energy in different countries based on their area of strength and the development they have made in those areas. In this regard, this paper would present information related to different forms of renewable energy sources with respect to development and strengths. By considering at fossil fuels, which have been used to address the challenge of energy on demand over the years and the challenges and limitation that have come with these methods and the need for the change to renewable energy would be considered to address this research problem.
The second research problem, which has been considered for this research is the identification of the major challenges and constraints to access renewable energy. To evaluate the issues related to the use of renewable energy, different limitation, which affect the sole use of renewable energy as an energy source would be evaluated.
The third problem, which would be addressed in this research is to suggest ways and solutions promote renewable energy reliability and meeting on-demand consumption amongst population for a greener future at the wider level. Different storage methods like hydroelectricity, pumped-storage, super capacitor rechargeable batteries, flywheel energy storage, latent heat thermal energy and many more would be considered to identify the solution to storage problems.
Methodology
For this research, the secondary qualitative method would be used. This method is based on the review of a literature review of secondary information. The secondary information would also be gathered from academic journals because this is one of the most researched topics in the academics realising its importance. The research findings from government agencies and organisations in charge of energy in these different countries would also be considered. The academic researches would be used to determine the major challenges to access renewable energy. Based on the primary and secondary information, the solutions would be proposed for the identified problems.
Research Objectives
To further explain the need why the world must stop its reliance on fossil fuel
To identify the major challenges and constraints those are encountered around the world to access renewable energy.
To suggest the different ways in which energy can be stored since some of these sources of renewable energy are affected by weather condition it is important the energy is the stored when they are generated during the peak period to meet energy demand during the off-peak period.
Energy Generation And Why It Is Important To Stop Reliance On Non-Renewable Energy
Introduction to Energy
Without energy, life is not possible, because in all changes, whatever its nature or the level at which it occurs: micro world, macro world, or the mega world, a certain amount of energy must be put into play. The greater the changes or modifications produced, the greater the amount of energy in play. In other words, humans need energy for whatever function they perform for the development of agriculture and industry (Pierson and Hlavacs, 2015). There is also a need for energy in all the processes that offer comfort in the daily lives of mankind including cooking, cleaning and transporting among a few. However, the energy that is consumed is non-renewable and it can disappear with greater and irrational consumption. The contemporary energy system, inheritance of the industrial revolution and the emergence and development of capitalism, rests on the consumption of fossil fuels and on a smaller scale, on nuclear energy (McGlade and Ekins, 2015). The primary energy resources include those resources that people receive directly from natural sources for subsequent conversion to other types of energy, or for direct use. Often primary resources must be extracted and prepared for further use.
The energy source for consumption mainly includes combustible (fuel), which include the energy of technological processes of chemical and thermochemical processing of raw materials, namely combustible gases, solid and liquid fuel resources, which are not suitable for further technological changes (Apergis and Payne, 2014). On the other hand, the exhaustibility of these sources has a negative environmental impact caused by their consumption. For humanity, it requires to look for alternative and renewable sources of energy that guarantee reliable, non-polluting and sustainable energy services for all inhabitants of the planet (Abas, Kalair and Khan, 2015). The objective of this work is to expose the importance of the energy issue, not only in the maintenance of life on the planet but also in the balance of nature. Also, to argue the significance of the use of renewable energy sources in the improvement of the quality of life, as alternative sources of energy to non-renewable sources.
Moreover, the primary energy resource that is a non-renewable resource is a naturally stored and accumulated in the soil of the planet reserves of substances, capable of releasing the energy contained in them under certain conditions. However, the formation of new substances and the accumulation of energy in them is much slower than their use. These include fossil fuels and products of their processing such as stone and brown coal, shells, peat, oil, natural and associated gas (Boluk and Mert, 2014). These particular types of non-renewable energy resources are fissionable (radioactive) substances located in the soil of our planet. These sources of energy are also obtained as the energy of gases, liquids and loose bodies that leave technological units with excessive pressure, which must be reduced before the next stage of use of these liquids, gases, loose bodies or when released into the atmosphere, containers and other receivers. The energy resources of excess pressure are converted into mechanical energy, which is either directly used to drive mechanisms and machines or is converted into electrical energy (Alshehry and Belloumi, 2015).
For millennia, the chemical energy of wood, the energy of water, wind, sun, were the main types of energy used by man. In the 19th century, the main sources of energy were fossil fuels including coal, oil and natural gas. With the development of technological progress in the twentieth century, energy scarcity has become increasingly visible, especially because of the multiple increases in energy consumption in the developing countries of the Asian region, which constitute about 80% of the world’s population (Nejat et al. 2015). Currently, oil production accounts for over 40% of commercial energy consumption, and for many decades oil will be one of the main sources of energy. Notably, based on available technologies, it is hardly possible to increase annual oil production. In addition, increasing environmental pollution and disturbance of the thermal balance of the atmosphere gradually lead to global climate change. Thus, the energy deficit and the limited fuel resources with increasing acuity show the inevitability of the transition to non-traditional, alternative energy sources because they are ecological, renewable and consume earth and sun for thermal and solar energy.
Brief History of Energy Generation
The history of energy, the way of development of the energy up to the present and future states is extremely interesting and important for understanding its significance in the development of civilization. Since ancient times, energy has been the most important factor in determining human life and the development of civilization. The history of energy from the ages, when a man has mastered fire, the energy from rivers, wind, and up to the present time reflects a constant search (Karier and Jourabchi, 2017). There were great discoveries, accumulation and transmission from generation to generation of knowledge, the most important achievements in the field of knowledge of the laws of nature. All the development of civilization, its technical achievements are associated with the integrated use of fire; from the ancient metallurgy and the production of ceramics, from steam engines to electricity, heat and nuclear power using high and ultra-high temperatures. Von Stuckrad (2016) also argued that fire as a source of heat has weakened man’s dependence on the external environment, made him much stronger, allowed him to save his strength and develop his mind.
The problem of finding sources of energy has always been in the first place in providing human life. By procuring food, sheltering from the cold, building a dwelling, man has increasingly improved the tools of labour. For a long time, the main source of energy was the power of his own hands and feet. Even having learned to obtain fire, the man still did not know how to use the forces of nature (Minasny and McBratney, 2016). There are several inventions that can be named; waterwheel, a windmill, a steam engine which throughout the history of human civilization played an important role in the technical progress and became the basis of modern engineering. The main principle underlying these inventions is the law of conservation of energy, according to which the energy of water, wind and steam (heat) is converted into mechanical energy capable of doing work (Jones et al. 2017).
Nevertheless, the mankind has realized that there are adverse consequences of the non-renewable resources that they pollute the environment that is the reason it has been criticized. According to Abdmouleh, Alammari and Gastli (2015), the renewable resources significantly contribute to pollution and global warming and they are responsible for the high volume of CO2 emissions and other toxic gases. Moreover, they are the cause of the greenhouse effect and acid rain. In addition to its combustion, its extraction and transport also generate pollution and alteration of ecosystems (Karier and Jourabchi, 2017). Their handling is dangerous, and reserves are doomed to be exhausted in the short or medium term so that they will become more expensive and their extraction more difficult. Notably, it is about the peak of oil to refer to the moment when, after reaching the maximum rate of oil extraction globally, production will enter a drastic decline until reaching the point of exhaustion.
Types of Non-Renewable Energy
Non-renewable sources include solid, liquid and gaseous fossil fuels originating from the slow transformation of organic materials, in deep layers of the earth’s crust, and fissile fuels, the primary source for the production of nuclear energy (Apergis and Payne, 2014). The former include coal, oil, natural gas, the latter, uranium and thorium. Oil and natural gas are not equally distributed on the earth’s surface. The coal, on the other hand, is more abundant and diffused more evenly, so much so that it can continue to satisfy the energy need for a few more years. The problem of coal is rather ecological where its use involves the release into the atmosphere of large amounts of carbon dioxide. With the same weight, in fact, the fossil carbon emits a greater quantity of carbon dioxide compared to oil and natural gas (Berg, 2017). However, for each of these three fuels, depending on the fields, there are significant differences in quality as regards to natural gas.
Total World Energy Capacity form Fossil Fuels
For thousands of years, the energy sources used were almost exclusively firewood, agricultural waste and animal dung. It was not until the seventeenth century, with the industrial revolution and the massive use of the steam engine in the industry, that the consumption of energy rose sharply, and the primary source became coal (Dogan and Seker, 2016). Then, during the twentieth century, the world’s energy needs increased dramatically. For decades the whole world has drawn on non-renewable natural sources (coal, oil, natural gas), without worrying about their limitations. Only with the energy crisis of 1973 has the awareness of the need to look for valid alternative sources of energy. The crisis was triggered by the provision of oil-producing countries (members of OPEC listing), which quadrupled the price of the barrel of oil while reducing supplies to the main importing countries (Acar and Dincer, 2014). The price continued to rise until 1980 when it reached a record $40 per barrel. The European Community then agreed to reduce the use of oil, favouring coal and nuclear energy, and for a policy of energy saving.
It was the years that saw the citizens give up the use of the car to favour public transport and start paying attention to the consumption of electricity and heating fuel. Today the price of the barrel of oil (considering monetary devaluations) has fallen back to about the levels from which it started, but energy saving and the search for alternative energy resources is still one of the primary concerns worldwide (Rahim et al. 2016). All the energy resources examined so far, our primary energy sources, which, in most cases, are then converted into secondary energy; from these sources, electricity is obtained, petrol for cars, fuel for aeroplanes, kerosene and light oil for lighting and for heating, charcoal, etc. The conversion requires complex plants and technologies that include oil refineries, coal-fired or gas-fired power stations, nuclear power plants, photovoltaic cells, etc. (Destek and Aslan, 2017). This phase follows the distribution of the final form (of electricity through the distribution network, of petrol in tankers) and the application of energy to a user appliance (a gas stove, a light bulb, an oven, a car, an airplane) to provide the required energy service (heating, lighting, moving etc.).
The final energy transformation by the user appliance is called conversion into useful energy. Each phase of this long path has a limited efficiency, often rather low, and causes the loss of a part of the energy, so precious and difficult to obtain. As a result, increasing the efficiency of energy conversion and use is focused and the level of efficiency of electrical and electronic devices would be tantamount to discovering a new energy resource (Boluk and Mert, 2014). According to various estimates, the efficiency of using primary energy would be well below 10% and, therefore, potential future improvements could have a significant impact on the global energy demand. Many French and American groups of scientists and the major manufacturers of electronic devices for information technology and household appliances are working in this direction.
Regarding the capacity of the fossil fuels, it is not evenly distributed throughout the world where almost 70% of the world’s proven reserves of recoverable oil are found in the Middle East, while natural gas is found in 29% in the Middle East and 43% in the former states Soviet Union (Kahia, Aissa and Lanouar, 2017). The total recovery resources and most of the bituminous sands and bitumen in the world are found, however, in North America, in the states of the former Soviet Union and a small part in China. This uneven distribution causes problems in different countries such as import dependence, supply difficulties, price fluctuations, which often result in political problems. Besides, there is also the concern to diversify resources, to become more and more independent on other countries for supplies.
In general, however, the development of nuclear power has come to a halt in response to the population’s concern about operational safety, the management of radioactive waste and the proliferation of nuclear weapons. These three aspects are the most important problems of the nuclear industry, and for now, they place a limit far below the technical potential for its development. By maintaining the current level of uranium use (below 60,000 tonnes per year), it is estimated that this resource can still be extracted for 64 years at a cost of around 130 dollars kg (More et al. 2015). Furthermore, by reprocessing and recycling uranium and plutonium, the number of years of availability of this fuel could be increased up to 50%. A further increase in availability could derive from the use of self-fertilizing reactors.
Importantly, society today needs energy and the millions of products that fossil fuels (gasoline, diesel, butane gas, oil, coal, etc.) offer to perform all the daily activities more comfortably. For example, butane gas, better known as cooking gas, is used to heat water to bathe, to prepare food; gasoline and diesel are used as fuels for automobiles (Baranes, Jacqmin and Poudou, 2017); whereas the coal is used to cook food or to keep the heat inside a home. Fossil fuels are also used for the manufacture of millions of other products such as clothing, plastics, computers, garments and automobiles among a few. For the elaboration of all these products and energies it is necessary to burn the fossil fuels; however, this generates serious problems because in the combustion of this carbon monoxide is given off which is extremely toxic and can cause serious health concerns (Bogdanov and Breyer, 2016). Additionally, the combustion results in the emission of carbon dioxide that is responsible for the greenhouse effect and global warming.
Global Fossil Fuel Consumption
Global fossil fuel consumption in large-scale could be dated back to the beginning of the Industrial Revolution. Data available shows that the consumption of fossil fuel coal, oil and gas as far back as 1800 onwards. Over the years the global consumption resources form fossil fuel has increased by more than 1300-fold with the first major use of coal since the industrial revolution began until the 1860s when focus shifted to crude oil and some decades later Natural gas consumption began around 1880-90s (Hannah Ritchie & Max Roser, 2018).
Global consumption parting changed in the 20th century with coal dropping from 96 per cent total consumption of fossil fuel in the 19th century now to around 33 per cent. Crude oil account for the largest source of fossil fuel being used today by supplying 39 per cent of total world fossil fuel consumption while natural gas provides 28 per cent. Below is a graphical representation of world fossil fuel consumption measured in terawatt-hours (TWh).
For this research, it is important to ensure that the base to carry out a comparative analysis is established so as to serve as a guide in later work when comparing renewable energy and non-renewable energy. In doing this the pattern of fossil fuel production total in the under listed countries measured in terawatt-hour (TWh) would be considered, the average fossil fuel production per capital across same countries measured in megawatt-hour (MWh) per person per year, consumptions from coal, oil and gas by the same set of countries in terawatt-hour (TWh) and the consumptions measured in megawatt-hours (MWh) per person per year. The countries include:
Germany
United State
United Kingdom
South Korea
Philippines
Africa but later Kenya would be singled out for the research
Germany
Taken a closer look at the activities of Germany over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
United State
Taken a closer look at the activities of the United States over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
United Kingdom
Taken a closer look at the activities of the United Kingdom over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
South Korea
Taken a closer look at the activities of South Korea over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
Philippines
Taken a closer look at the activities of Philippines over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
Africa (Kenya)
Taken a closer look at the activities of Africa over the last 50 years in terms of fossil fuel production, production per capital, fossil fuel consumption and consumption per capita.
Types of Renewable Energy
There are different types of renewable energy that are illustrated below why further research work are done in the subsequent chapter.
Hydropower
It is the most popular and most substantial form of renewable energy that is popularly used in the modern-day society. Water flowing along rivers is harvested in dams and released through turbines to provide electricity. The effects of the quantity of water on the production of electricity are to be determined. Impact of the size of turbines employed in the production of hydroelectric power is also among the basics of the study. Power production effects on the ecological cycle of aquatic creatures are also to be analysed and recommendations made on the ways of improving production and maintaining the marine environmental niche.
Geothermal energy
The earth’s core located many miles below the earth’s surface can reach hot temperatures of about 9000° F. Heat generated produces geothermal energy and flows outwards heating the surrounding environment leading to the formation of underground reservoirs for hot water and steam. The pools can be adapted for a variety of uses such as electricity generation or heating build sites. Various aspects of the produce hot water and steam such as temperature and pressure are to be determined and their effect on influencing the amount of heat and electricity evaluated.
Solar energy
The sun is the ultimate source of solar energy. Solar energy comes in the form of light and heat which is then harnessed and converted to electric energy for heating, cooling and lighting buildings. In the study of solar energy, the quality, quantity and distribution of energy from the sun are to be determined. A pyrometer system is used to compare measurements at different cloud observations at different hours of the day and the results evaluated to determine the quantities under study (Acar and Dincer, 2014). The effect of air pollution on the amount of light produced by the sun is also studied at different points in the solar spectrum using solar cells and current and voltage meters. The working of solar concentrators is also to be evaluated and the procedure of how it harvests solar energy is evaluates
Wind energy
Wind contains a vast amount of energy that has been often harvested from the past in sailing of ships along oceans, grinding of grains and other cereal products, and pumping water. In the present times, advanced wind turbines have been developed to offer efficient means for capturing wind energy for generating electricity. Steady wind speeds of greater than 12 miles per hour are required over the year for effective generation of electricity (Kahia, Aissa and Lanouar, 2017). The anemometer and wind vane are to be used in the research to measure the wind speed and wind direction respectively at separate times of the day. The effects of topography on the speed and direction of wind are also to be evaluated. Moreover, the effect of the size of the wind propeller on the production of electricity is determined.
Bioenergy
They are produced from biomass which entails living organisms and decomposable trash. It is derived from organic matter. Production of biomass is less costly and has a lower impact on environmental pollution. The output of bioenergy is to be studied in the research, and the conversion of biomass to biofuels is also explored (Mondal and Bansal, 2015). The type of plants that produce a large quantity of heat energy in a given amount of biomass is evaluated. The amount of energy that can also be produced by alcohol fuels is exhausted during the research.
Renewable energy
The focus of chapter 3 is on renewable energy where the efforts of different countries are taken into consideration to acknowledge their strength in the specific field. It is because renewable energy acquires through a natural process, which is continuously replenishing. The renewal energy is different from fossil fuel in form of diversity, abundance, and potential. It is important to acknowledge the fact that renewable energy does not possess the potential to use greenhouse gases, which can be the cause of climate change, neither polluting emissions (Twidell and Weir, 2015). In this regard, its cost is falling at a sustainable rate; however, the cost of fossil fuel is increasing despite its present volatility. The renewable energy utilizes for various purposes in commercial and industrial uses that reduce the excessive use of coal, oil and natural gases. For further discussion, it is essential to examine the capacity, environmental factor, technological techniques, challenges and the form renewable energy resources used in different countries of the world (Li and Hedman, 2015).
The countries who have adopted for themselves an energy strategy focused specifically on renewable sources, as the most environmentally friendly, inexhaustible, do not require mining, burning carbon-containing fuel, and consequently, the utilization of a huge amount of combustion products. Renewable energy acquired from natural resources such as sunlight, water currents, wind tides and geothermal heat, which are renewable resources. The use of this energy helps to restore the vitality of the environment. For further discussion, it is essential to examine the capacity, environmental factor, technological techniques, challenges and the form of renewable energy resources used in different countries of the world.
Solar Energy (Germany)
Germany is a leading country in producing electrical energy. The undeniable advantages of this type of energy include noiselessness and environmental safety, namely the absence of harmful emissions into the atmosphere during the processing of solar radiation. Solar power acquires from sunlight in terms of electricity through using photovoltaic (PV) or indirectly utilizing concentrated power. It has been observed that concentrated solar energy use mirrors or lenses in order to keep its focus on the large portion of sunlight in form of a small beam. It is undeniable fact that solar energy receives in form of light and heat, which later harnessed and converted in form of electric energy for heating and lighting the building (Li and Hedman, 2015). For solar energy, it is essential to determine the quality and quantity of energy acquired from the sun. In this regard, the pyranometer system is used for measurement for the observation of different clouds during different hours of the day, which helps to evaluate the required quantity.
These technicalities are employed in Germany who has become the world’s first leading country who employ renewable resources. The renewable energy of Germany mainly consists of wind, solar and biomass. Germany possesses the world’s largest photovoltaic installed in 2014 to acquire solar energy. The country breaks its own solar record through producing 85% of electricity from renewables. In figure 7 below it shows a pictorial view of a different kind of renewable energy being consumed in Germany. In this regard, Germany produces more than 1,000 megawatts (1 gig watts) of energy is produced from the sun. Germany is one of the world’s leaders who has invested their effort in the production of nuclear power (140 TWh / year). However, due to the incident of Fukushima, the country has decided not to use nuclear power plants for the production. In order to prevent the environment from the harmful effects, the eight nuclear plants were stopped and other remaining will be closed in 2022. This country possesses several solar energy plants that fulfil the need of the population.
To avoid the maximum use of fossil fuel, which is expensive to fulfil the daily need of the population, the use of solar energy is the best way to cater to domestic and industrial needs. The generation of energy through solar power causes the country to face certain challenges to meet the requirement of electric power. The electricity generates from the solar cells consider sensitive to the environment such as the passing of a cloud which can turn down the electrical output by 50% in a few seconds. It is expensive to fix the problem. It is hard to store solar energy at night where solar light can be stored through batteries, which cost $65000 per house. In this regard, it is important to use a thermal power plant to store the energy. The experts educate the policymakers and business leaders regarding the role of energised. In this respect, it was essential to make the policy makers realize about the development of a solar system to change the energy system of Germany. In this way, the country does not need baseload power plants to run them through fossil fuel, which is not environment-friendly. In order to maintain the climate change, the country prefers to use solar energy instead of fossil fuel that can pollute the environment.
The strategy was laid out that revealed in detail about long-term effects of using fossil fuel rather than consuming power through renewable resources. In the beginning, the country did not possess command to fulfil the requirement then experts trained and receive the necessary experience, including experts in installation of solar systems. Photovoltaic plants installed beside conventional system to keep the demand of energy inflow. Besides solar energy, the country produces energy through wind and installed turbines to meet the need of the country (Slamova et al., 2016). The country does not completely rely on the wind energy as compare to solar energy because it produces energy more than the required capacity. The peak time of generating power depends on the weather condition when the sun is too bright it becomes convenient to acquire maximum energy and when there is lack of sunlight or the weather is too cloudy to turn down the generation.
The graph reveals the fact that there is a certain peak period where due to the hot summer season the demand for energy increases and turns down in the month of December and January. In this period, the country faces the difference between supply and demand of electric energy.
Hydroelectric (Unite State)
A hydroelectric power plant is a place where cheap electric energy is produced. The energy of water currents, with the help of hydraulic turbines, generators and transformers, turns into an electric one and reaches consumers by high-voltage wires. Such a source of energy is renewable (Yang 2016). Despite the high cost of constructing such power plants, in time, they fully pay for themselves at the expense of the electricity sold. On the other hand, fossil plants can only generate 50% compared to the hydro turbines. Hydropower projects such as Hoover Dam, Grand Coulee Dam, and Tennessee Valley Authority plays an effective role in producing electric energy. In this regard, the biggest hydropower Grand Coulee Dam is located in Washington where it produces more than 70% of the electricity.
The United States is a leading country in the world who possess hydroelectric dams because of its plentiful supply of rivers and effective technology. In this respect, the country overall hydropower projects are producing 94% electricity. In order to fulfil the need of the country, it becomes essential to make less use of fossil fuel where coal and natural gas to acquire the energy. These sources are enough to pollute the environment as compared to hydroelectric power, which is fuelled by water. In this respect, it is considered that clean fuel and could not pollute the air. In fact, hydroelectric power is the domestic source of energy where each state is allowed to produce their own energy according to the required capacity rather than relying on international fuel resources (Yang 2016).
On the other hand, it has certain benefits such as damming the water; changes water flow as well as construct roads and power line. In this way, it is more effective for the country to use hydroelectric power plant. The technology the U.S. has employed is related to hydraulic engineering facility using turbines to generate electricity during a peak load and to pump water back to the dam while reducing it. The jet turbine rotates the generator. When centrifugal pumps are disconnected, the system acts as a normal hydroelectric generator. When the drive coupling is turned on, the water turbopumps are accelerated to the operating speed. Then the generator switches to the electric motor mode. The turbine valve closes, the pump valve opens, and water is pumped back behind the dam, to increase the level of accumulated water used later to produce hydroelectric power.
The country is facing a challenge in form of climate change such as a change in the pattern of rainfall, droughts reducing river flows and daring lakes as well as well melting glaciers are the biggest threat s for the country. Beside hydroelectric power, US depends on another renewable energy that is wind energy where turbines are used to acquire electricity. It is one of the cheapest sources of acquiring electricity where the energy depends only on the speed of the wind. The major strength of the country depends on this renewable source to cater the need of the country. It is because of the growing demand and climate change the electricity requirement cannot be fulfilled. This can be measured through the monthly generation of the electricity through hydroelectric power.
It reveals that consumption of the electricity is increasing day by day especially during the hot seasons such as April, June, July, and August. These are the peak months when demand grows more and turn down in the month of winter. On the other hand, the growing consumption has to face climate change that cannot make the country completely rely on only on Hydroelectric.
Wind Energy (United Kingdom)
Wind energy is a renewable energy, which is one of the cheapest resources. It is because wind is a form of solar energy, which is, generate through mechanical power. The United Kingdom is producing maximum energy from the wind energy where it has set the record for producing 10 gig watts. It is because the UK possess the windiest regions in Europe where it is easy for the country to generate maximum energy. The UK prefer to use this renewable because it leaves a little harmful effect on the environment as compare to the fossil fuel that can pollute the environment and can be the cause of various diseases. For this, UK has planted wind turbines both onshore and offshore around the country, which convert kinetic energy in form of mechanical power. The generator can turn this power into electricity in order to power homes, industries and so on.
There are certain challenges that the UK concerns relatively to wind energy such as noise produces through rotor blades can be the cause of noise pollution, visual impacts, and birds are killed who get into the rotors. Beside them, UK industries, require large vessels, lack of standardization and experienced people to handle it appropriately (Stephens and Walwyn, 2016). On the other hand, the statistical analyses of 2016- 2017 reveals the fact that the country in certain peak periods such as Jan, Feb, and Nov cannot cater the required need. On the other hand, the requirement turns down during the period of June, July, and August. It all depends on the weather condition.
In this regard, the UK use the alternate renewable resources such as solar energy to fulfil the demand of the country during the peak period. However, the wind energy is the strength of the country but in a certain period, it becomes difficult to cater to the need of the country. To keep it into balance, the country utilizes solar energy for power generation.
Tidal Energy (South Korea)
Tidal energy is relevant to hydropower where it uses the kinetic energy of the tides is used for generation of electricity. The construction of the tidal coast developed on the seacoast where it makes it possible to build large-scale water intake basins as well as bays and mouths of rivers where the level of tidal waves occur at 4m. It is important to acknowledge the fact that only 2% of electricity demand covers from hydropower generation. It is because the country assumes that it is one of the conventional ways of producing the energy, which they have replaced with impressive tidal resources. The country possesses approximately 254 tidal stations, which possess the capacity to produce 260 megawatts. In this regard, South Korea use stream generators, which are like wind turbines, but they are below the surface of the water (Jo et al., 2015). The turbine and generator convert the flow of the water coming from the opposite direction in form of tide where kinetic energy converts into electricity. In this respect, the water is 830times denser as compare to the air and can generate electricity at a lower speed. From the perspective of the environment, South Korea prefers to use this technology because tidal is a renewable source of electricity which cannot be the cause of emission of gases responsible for global warming or can cause acid rain due to fossil fuel electricity generation. It can threaten tidal flat wetlands that support the unique ecosystems and host tens of thousands of migratory birds. These are possible challenges the country is facing due to tidal energy. Apart from that, the country invests great effort to meet the required standard of the electricity. Its demand touches the peak in the hot summer days from May-July and comes down during the winter season from November-January
The country possesses other alternate renewable resources such as hydropower, but the country prefers to make use of tidal energy through which they can generate energy to the required demand.
Biomass Energy (Kenya)
Biomass is considered an organic material, which acquires from plants, animals, and it is one of the renewable resources. This renewable fuel is considered neutral for CO2 emissions. The biomass technology helps protect the earth and atmosphere from greenhouse gas emissions. Biomass differs from other types of fuel in that it was recently “alive.” The combustion of biomass is neutral for CO 2 emissions. This means that during combustion, it releases as much CO 2 as was absorbed in the power plant during the growth process (Jones et al., 2018). The main sources of biomass in Kenya related to charcoal, wood fuel, and agricultural waste. It is because the country wants to fulfil the demand of the population, which requires energy substitutes.
The challenge that the country is facing relates to the biomass demand and supply that has disturbed the balance and put more pressure on the forest, which can cause degradation of land. The country possesses the capacity of producing 70% of energy demand and provides more than 90% of the rural houses. The technique Kenya apply in biomass requires the country to acquire products from the agriculture sector and industries such as coffee husks, coconut shells, and bark, offcuts, and timber shots. It is because they are considered suitable for the gasification (Tummuru et al., 2015). The country diverts their attention towards the use of biomass energy because of the increment in fossil fuel prices and its excessive use contribute to climatic change. These aspects are enough to grab the attention of the developing countries. It is an undeniable fact that biomass energy is a great danger for the forests, agriculture and human settlement. The other alternative resources that the country possesses related to natural gas and nuclear power. However, the country avoids making use of them because they are harmful to the perspective environment (Jones et al., 2018).
To fulfil the demand of the country, it becomes essential to meet the requirement in the peak period as shown in the graph and it turns down in the period from October to Jan. The country possesses other renewable resources such as solar energy, wind energy, and geothermal. The country does not depend on the biomass and caters the daily need through solar energy and wind energy. It is because these resources are cheap and provide enough electricity to overcome the requirement.
Geothermal (Philippines)
Geothermal possess significant position in the developing countries. In this regard, heat generation is the most important aspect of this system. There are various methods of use for transferring the heat available undertint the earth. The geothermal industry in the Philippines is quite huge that produce approximately 1900MW. To meet the electric requirement in the country, 1930MW electric power is installed in the islands of the Philippines where steam hydrothermal plants work to provide required electricity in the country. The nature of the sources, temperature, power plants and urban heating networks are connected with underground tanks. The temperature of the steam should be suitable for generating electricity at 200 OC. Geothermal power plants use hot rocks to heat the water in order to pump the underground cavities. Superheated steam, form because of geothermal processes, is brought to the surface of the earth and uses the turbine blades of steam generators.
The country favours geothermal because it is one of the clean energies as compared to the combustion of fossil fuel. In fact, it is environment-friendly because the intensity of carbon, hydrogen sulphide and methane are low as compared to the fossil (Bertani 2016). On the other hand, there are certain challenges that Philippine is facing related to the water. It is an undeniable fact that due to climate change, the reservoirs of water are changing their patterns in the future; there is a possibility that lack of water cannot make the country possible to acquire maximum electricity. The country has other alternative renewable resources such as solar energy, wind energy, and Biomass energy. In this regard, it is not essential for the country to rely only on geothermal (Bertani 2016). However, it is the strength of the country, but other alternate renewable resources enable them to meet the requirement. In fact, they are more suitable for them despite using the water reservoir.
There are certain peak periods where it becomes essential for the country to increase their productivity of energy as shown in the graph. On the other hand, February and March are the periods where the demand is comparatively low.
Challenges And Limitation Of Renewable Energy
The focus of this chapter is to provide a comprehensive overview of the different limitations and challenges associated with renewable energy. Some common challenges and limitations related to renewable energy include capital cost required to generate large quantities of electricity, storage of renewable energy on demand, and weather condition as the renewable energy is affected by the solar energy, wind energy, rainfall, and tide energy with respect to hydroelectricity. This chapter presents some of these challenges and limitations. In the evaluation of any renewable power plant, it is important to consider the economics of projects as one of the major limitations and barriers in the success of these projects is the economic or capital structure barrier.
Capital Cost
As demonstrated by the outcomes of different research projects on renewable energy, it is clear that one of major barrier in the renewable energy is the cost capital. A huge capital and financial outlay are required for setting the facility for the generation of renewable energy facilities (Kahia, Aïssa, & Lanouar, 2017). The cost is required for the installation of solar panels, wind turbine, as well as the hydroelectricity plants and all these processes require the high cost. The cost for different renewable projects is gained from different grants, as the new technologies for generation of renewable energy require the considerable amount of uncertainty, which is a barrier to the development of this energy. This uncertainty is the cause of high capital cost raising the price of integration of this technology (Ghaffour, Bundschuh, Mahmoudi & Goosen, 2015). In addition, the cost required for purchasing efficient equipment is often greater than the standard alternative and time period for payback or return is usually unacceptable.
The capital cost is described as the upfront costs, which are required for the construction of plants and carry out prime maintenance work beyond some typical expenses required for operating these plants. The capital cost is termed, as the prime barrier to renewable energy as the installation of different plants for renewable energy requires high capital. It is a matter of fact that it is cheap to operate renewable energy, for instance, wind or solar energy due to free fuel and low maintenance is required (Twidell & Weir, 2015). However, the major capital cost is required for purpose of building the power plants and installation of wind and solar farms.
In the year 2017, the average cost, which was required for installation of the solar system, was more than $2,000 per kilowatt for installation of a system at larger scale, while the cost required for the residential system is $3,700. On the other hand, the cost required for the installation of wind power system is approximately $1,200 to $1,700/kW, which is very high (Hand, Augustine, Feldman, Kurup, Beiter, & O’Connor, 2017). For the purpose of installation of the natural gas, the plant is approximately $1,000/kW. This has shown the need for higher construction cost for these plants (Watkins & McKendry, 2015).
Due to the higher construction cost required for the renewable projects, these projects are considered as risky and it is usually harder for developers or utilities to justify the investment made on these projects. On the other hand, the comparison of cost with the lifespan of different renewable energy products has revealed that after using capital cost for installation of renewable energy technology, the energy generating process, later on, would be cheaper. The evaluation of different projects has shown that the costs for the wind power as well as for solar power has been reduced. The cost of renewable energy has been continuously reduced and the similar pattern can be seen in the next years (Arnold & Yildiz, 2015). However, most of the countries do not prefer the installation of renewable power plants due to the high cost of installation and capital cost for labour work.
In addition to this, it is significant to consider that the cost required for infrastructural development and setting-up the plants of renewable energy is very high (Twidell & Weir, 2015). Some countries have some alternative resources and therefore, they consider that capital cost required for installation of renewable energy plants is very high. As the power plants for different non-renewable power plants are already available, therefore, the countries rich in these non-renewable energy resources are not ready to bear capital required for renewable energy plants. Setting up the renewable energy power plants is very expensive, and several countries have non-renewable power plants are reluctant to the spent capital cost required for the renewable power plant (Gowrisankaran, Reynolds & Samano, 2016). The establishment of renewable and clean energy plants such as wind or solar energy is beneficial for the environment; however, capital required for installation of set-up is a major barrier to its development.
In addition, the capital cost required for the workers required to operate these plants is very high as compared to non-renewable energy resources. The substantial workforce required for renewable power plants is comparatively high as the installation of wind, solar, or other power plants is very high. On the other hand, the non-renewable energy production requires only a few workforces and it is therefore economical. This is the reason that cost for the development of power plants for renewable energy is considered as a major barrier (Watkins & McKendry, 2015). Different projects are planning to develop strategies to decrease the economic resources required for installation of projects as the use of renewable technologies can be considered as a prime solution for decreasing reliance on fossil fuels.
Some of the capital costs required for the adoption of technologies for the renewable energy include the economic cost, initial cost, transaction cost, and incentives. The specific capital cost is required for different renewable energy plants and the concept of specific capital is effective for comparison of the cost of different technologies and among these, the least expensive is solar, yet the other forms are expensive. The cost required for installation of the solar panels, wind turbine, as well as the hydroelectricity plants is very high. Therefore, there is need of the upfront investment for these projects and in addition to the cost required for building these plants, the cost required for maintaining these plants is also very low. The initial cost is considerably high increasing the cost required for generation of electricity as compared to other conventional sources, which are used for generation of electricity (Kahia, Aïssa, & Lanouar, 2017). Considering all these aspects, it is clear that the capital required for installation of renewable energy technologies and plants as well as maintenance cost is still a major challenge.
Furthermore, the transaction cost is also associated with renewable energy generation and this, therefore, increases the total costs for production. This cost is the cost associated with resources as well as also include the time cost for establishment of this energy technology. The transaction costs required for small or large-scale renewable energy projects are high as the processes related to small or large-scale projects are almost similar and therefore, these technologies are therefore unaffordable for producers and for consumers. The capital cost required for these plants is also a limitation as for the lack of credit facilities for purchasing energy technologies and high interest on sustainable energy resources acts as a prime limitation for development of renewable energy plants (Yaqoot, Diwan, & Kandpal, 2016).
Political and Regulatory Barriers
There are some other barriers related to the development of renewable energy. Different areas are reluctant to adopt technologies of renewable energy and there are some other barriers along with the above-described barrier. One of these barriers is the regulatory and political barriers. The lack of regulations or policies regarding development and use of renewable energy plants is a major barrier in the installation of these plants. Further, lack of regulatory measures reveals the regulatory risks and therefore, investment in such projects is limited. For the advancement of renewable energy projects in such areas, it is important to ensure that policies and regulations are developed to overcome these barriers (Abdmouleh, Alammari, & Gastli, 2015). In some countries, such as Sub-African countries, there are some policies and regulations for the renewable energy plants; however, still, the implementation is limited due to other barriers such as lack of social capital for installation or immature policies or regulations.
In addition to a lack of policies, the presence of well-defined policies can also be a limitation as this can limit the participation of private sector in making an investment on renewable energy projects. As the renewable energy project is based on the large capital, therefore, the progress of the country towards such projects could be due to the failures of policymakers.
Technical Barriers
The technical barriers are the other limitations of renewable energy development and these barriers include the lack of appropriate infrastructure and technology required for supporting the renewable technologies. The willingness of different countries to invest in the renewable energy projects due to the infrastructure required for the installation of technologies is another limitation. In addition, the lack of skilled and trained personnel for purpose of training, maintaining and operating the structures of renewable energy projects is another technical barrier. This technical barrier becomes more intense in the regions with a low level of education or competencies as fear of failure is associated with the installation of technologies in case of inappropriate training or knowledge (Luthra, Kumar, Garg & Haleem, 2015).
Furthermore, in some countries, these technologies are considered as cost disadvantaged as lack of technical skills requires import of these energy sources and technical team from other countries, which is expensive. Further, lack of different physical facilities, which are required for transmitting and distributing network along with services and equipment is another infrastructural challenge associated with the development of renewable energy, especially in developing countries. As imported equipment for the production of renewable energy are expensive and therefore, the production of renewable energy is expensive and unaffordable (Helms, Salm, & Wüstenhagen, 2015).
The inadequate connectivity to the grid is another technical barrier and this makes the transport of energy from the production unit to consumptions point resulting in a high level of transmission loss. This can lead to low interested investors in these projects and therefore, they are not ready to invest in such projects due to significant technical barriers associated with the condition. The inadequate equipment servicing and maintenance along with low technology reliability can be associated with renewable energy development and therefore can act as a major technical barrier hindering developing of these projects.
Social-Cultural Barriers
Socio-cultural barriers are also associated with the use of renewable energy, an example of such barrier is the unwillingness of households to adopt the renewable energy because of low reliability, and this can lead to failure of renewable energy development. The disengagement and disinterest of people regarding these energy sources are a limiting factor for the development of these technologies. Further, the lack of awareness and knowledge of renewable energy technologies among rural communities is another socio-cultural barrier related to the development of renewable energy (Luthra, Kumar, Garg & Haleem, 2015). It is difficult to orient the uneducated people towards the disadvantages of the extensive use of non-renewable energy resources and the technical benefits associated with the use of renewable energy.
Difficulties to Generate Large Quantities of Electricity
Another barrier related to the renewable energy is that the capacity of these power plants for generation of electricity is not enough. As compared to the traditional methods used for generating electricity, for instance, the fossil fuels, the quantities of energy produced by renewable technology is very low and cannot meet electricity demands. It is a considerable fact that still the fossil fuels can produce large quantities of energy and relying only on the renewable sources would result in energy scarcity.
The energy generated by the solar energy or other renewable sources is unpredictable and can vary with respect to weather conditions and therefore, it is unpractical to generate the electricity, which can meet growing demands. Furthermore, for generating large quantities of energy, there is a need for the installation of large plants with greater efficiency and the whole process require large revenue. The installation cost for plants with higher energy generation as well as the ensuring fully functional system along with storage is the lengthy and costly process. Another important point related to the generation of the larger quantity of electricity by the use of renewable sources is the social capital limitation of renewable energy is that there is a need of huge upfront capital for the outlay. There is a need for huge financial outlay for setting up the generation facilities for the generation of renewable energy.
Storage of Electricity
The storage of energy produced by renewable sources is another major barrier regarding the sole use of this source for generation of power and electricity. Most of the renewable energy sources are variable, for instance, the energy generation but most of these renewable sources are based on weather condition. For instance, solar power is not available at night-time, wind energy requires wind for production, and tidal energy is dependent on weather favourable for the formation of tides. Therefore, to meet the demands of energy with the use of renewable energy technologies. The most important thing in this regard is, therefore, storage of energy. There are different storage techniques used for the storing renewable energy such as solar cells and pumped water storage, but none of them is efficient or economical for efficient storage (Larcher & Tarascon, 2015).
The entire energy cycle of renewable energy is the capturing of energy, conversion, storage, and retrieval for purpose of final use. The storage of energy is therefore important and for this purpose, there is the need for installation of modest renewable capacity for supplementation of power, which is supplied from the grid. There is a need for reserve generators for storage of energy. The storage capacitors are used for this purpose are expensive and therefore, the cost of storage is another barrier related to the use of renewable energy. For instance, Tesla PowerWall is used for storage of renewable energy, yet the price for this battery is $407 per kWh of storage capacity and it can only discharge only half of the energy stored and therefore, the actual cost is very high (Jurgens, 2015).
The use of batteries or reserves generator for storage of energy is also limited as the charging and discharging of energy by these batteries can be carried out at a specific speed and if the speed fluctuates, it can lead to overheating and therefore, the batteries can become out of order. In addition, another factor, which makes the storage of energy by renewable sources as a limitation is the cost of these storage devices. For instance, for a discharge rate of 20 kW, a storage bank of 100 kWh is required, and the cost required for this storage bank is very high.
Reliability and Demand
Another major barrier related to extensive use of renewable energy is that reliability of the renewable energy resources is low. To rely on the renewable energy, it is important to reduce energy consumption, so that limited amount of energy produced by renewable energy can be used to meet growing demands, which is not possible. Therefore, it is difficult to rely only on the renewable energy and different energy resources are required for meeting growing needs of energy. Furthermore, the reliability of renewable energy is still low as the renewable energy technologies are new to the market and therefore have limited efficiency (Yaqoot, Diwan, & Kandpal, 2016). This is the reason that different forecast issues are related to using of this energy source and most of the investors are not ready to invest in this type of energy generation.
Another limitation is demand as the energy generated by the use of renewable energy resources is not enough to meet the growing demands for energy. The present facilities set up for the generation of energy with the use of renewable resources is not sufficient to meet the extensive needs of the population. More technologies advancements are required to generate the large quantity of electricity, which can meet the demands of the population for the long term. It is difficult to rely on the renewable energy, as the generation of energy is dependent on weather, for instance, wind and sun (Luthra, Kumar, Garg & Haleem, 2015). If the atmospheric condition were not favourable as required by the renewable energy plants, these technologies would fail to produce electricity, which is equivalent to demands of the population. Thus, this shows the major limitation of renewable energy.
Weather Condition
The security of renewable energy supply under climate change conditions has also become an important consideration in the formulation of energy strategies in various countries. Therefore, analysing the vulnerability of renewable energy systems under climate change conditions and improving their adaptive capacity according to actual development is a crucial step to achieve sustainable development. At this stage, climate change research, policies, and planning are more focused on energy conservation and emission reduction to reduce greenhouse gas emissions, thereby mitigating climate change trends (Wang, Palazoglu & El-Farra, 2015).
Wind energy is a typical meteorological energy source and a renewable and clean energy source. In the future, the proportion of wind power and the global energy structure will increase significantly. However, the reality is that the healthy development of the wind power industry is not an easy task to overcome the “meteorological conditions”. Wind energy is subject to meteorological conditions in weather. Wind energy has a strong “meteorological property”. The bottleneck currently faced by wind power development is mainly caused by the instability of meteorological conditions, mainly due to the intermittent and fluctuating wind, regional and sudden weather (Ellabban, Abu-Rub, & Blaabjerg, 2014).
The vulnerability of wind power equipment to meteorological disasters is another important reason for the development of wind power. Wind farms and transmission lines are generally located in an open natural environment. Typhoon, low temperature, lightning, and other severe weather will affect the wind farm and grid security. This will not only damage the wind farm equipment but also affect the safety of the grid (Alsharif, Kim, & Kim, 2018).
As a kind of climate resource, solar energy will be affected by various meteorological factors. For photovoltaic power generation, the temperature is one of the important factors affecting its power generation efficiency. Crystalline silicon solar cells are the main equipment for photovoltaic power generation. Due to the physical properties of silicon materials, the temperature rise will cause the open circuit voltage and fill factor to drop, which will lead to a decrease in output power.
Based on the meteorological observations in, the influence of local meteorological factors on photovoltaic power generation was analysed. It was concluded that sunshine hours, solar radiation, relative humidity, and temperature are the main meteorological factors affecting solar photovoltaic power generation. If sunshine hours are stable, less affected by weather changes and stable solar energy resources, which is very beneficial to the development and utilisation of solar energy resources. Photovoltaic power generation and solar radiation are linear in each season. The stronger the solar radiation, the more photovoltaic power generation; the lower relative humidity plays an important role in enhancing photovoltaic power. The lower the relative humidity, the stronger the output power of the photovoltaic power station; Changes in ambient temperature can have destabilising effects on photovoltaic power plants. Strengthening the assessment of climate and environmental resources for building stations and research on meteorological forecasting technology for solar photovoltaic power generation can actively promote the development and utilisation of renewable energy in the western region (Wang, Palazoglu & El-Farra, 2015).
There are many factors affecting the amount of solar photovoltaic power generation, such as solar radiation intensity, ambient temperature, relative humidity, wind speed, installation angle, photoelectric conversion rate, and the like. Among them, for installation angle, photoelectric conversion rate, etc., it is possible to optimise the output of photovoltaic power generation by means of device adjustment and technological advancement, and solar radiation intensity, ambient temperature, relative humidity, and wind speed are beyond the control of people. The point is precisely the key to affecting the output power of photovoltaic power generation. The ambient temperature and the intensity of solar radiation mainly affect the output power of photovoltaic cells.
The relative humidity and wind speed indirectly affect the photovoltaic power generation by influencing the radiation. For example, the relative humidity increases, and the water vapour in the air blocks the effective radiation on the ground. The actual output power of photovoltaic power generation is the result of the interaction of these trends. The early warning factors selected in the initial steps are solar radiation intensity, daily maximum temperature, relative humidity, and wind speed as for early warning factors. The above warning factors can be obtained from daily weather forecasts (Twidell & Weir, 2015).
Pollution and weather have effects on the efficiency of solar energy equipment resemble twilight, with the disadvantage that people cannot always predict pollution and weather conditions. Pollution degrades the efficiency of solar cells, and cloudy weather reduces energy in the sun’s rays. In areas with ever-cloudy weather and high levels of pollution, such as major cities, solar energy has lower efficiency. Solar energy experts develop newer solar energy in an attempt to overcome these effects through creative design (Alsharif, Kim, & Kim, 2018).
More and more technical possibilities for extracting energy are being tested. Among other things, researchers have tried to extract energy from sea waves. However, the technology has not proved to be as effective as it was hoped when there was a lot of wear because of the waves and storms. On the other hand, it seems that the tide can help us in the energy issue. The opportunity to extract energy using tidal water has given positive results in the first tests.
Water levels at the world’s coasts change, so there are high tide and low tide with six hours and a quarter of a quarter. The difference between ebb and river varies from almost nothing in shielded areas to up to 12-15 meters, where the water is compressed into narrow channels. These changes in sea level are called tides and are especially due to the impact of the earth’s mass on earth (Wang, Palazoglu & El-Farra, 2015).
The weight impact of the moon draws into all the constituents of the earth, but there is a difference in power depending on the distance to the moon (Twidell & Weir, 2015). The closest to the moon is the attraction, while the distant parts of the earth experience a significantly less attraction. The result is that the mass of the moon not only draws into the ground but also tries to stretch it to form the shape of an American football. The solid crust is affected slower by this attraction than the garden does. It is therefore first the earth’s water masses that the moon sets in motion. Earth’s rotation means that each point of the earth has the largest and least distances to the moon approximately once in the course of a day. The moon itself, however, also rotates and has a resolution of 27.3 days. The consequence of this is that it is about 12.5 hours between two high tides.
The sun also draws into the ground with a force, which depends on the distance between the two. The effect is significantly weaker than the moon’s impact, but it means that the tide’s strength changes as the phases of the moon. At new moon and full moon, the attraction of the sun and the moon reinforces each other, and the tide is, therefore, the most powerful during this period. By increasing and decreasing the moon, the attraction of the sun and the moon counteract each other so that the tide becomes weaker. The two phenomena are called Spring River and nip river respectively. In addition to the tide, the sea’s water level is also dependent on the weather and wind (Kondziella & Bruckner, 2016). A powerful and sustained blow can thus push large amounts of water into the coastal areas. Culminating wind power and tidal at the same time, it can cause violent floods, called storm floods.
Impact of Hydroelectric Power Plant on Weather
It is a matter of fact that different renewable energy plans are affected by weather conditions, which can act as a barrier to the renewable energy plants. However, the impact of these renewable energy plants on the climate and weather condition is another barrier, which can limit the use of renewable energy. The International Energy Agency (IEA) report has shown that doubling the world’s hydropower generation by 2050 will reduce annual greenhouse gas emissions by 3 billion tons. The engineer against the construction of large hydroelectric power stations stated that dams and reservoirs are responsible for almost a quarter of all methane emissions produced by humankind ((Kahia, Aïssa, & Lanouar, 2017).
According to the IEA report, hydropower produces 16.3% of all electricity used on the planet. Thus, the share of hydropower in the world energy balance is higher than the share of nuclear power plants (12.8%) but much less than the share of fossil energy sources. During the operation of the plant, carbon dioxide is not thrown out and therefore, it is considered that electricity generated by the movement of water can be considered relatively clean as compared to other sources of renewable energy. However, there are different climatic impacts of hydroelectric power plants. As the large dams are a great source of greenhouse gas emissions, therefore, they have produced an intense impact on the environment (Ghaffour, Bundschuh, Mahmoudi & Goosen, 2015).
The plans for the construction of large HPPs are always based on the assumption that the nature of the river flow in the future will be a reflection of its past. However, climate change is causing a significant and unpredictable change in the pattern of precipitation. On the other hand, droughts that are more frequent will make many hydropower projects economically unprofitable. Additionally, stronger precipitation and flooding will increase pollution by sediment (reducing the useful lifetime of HPPs) increase the risk of erosion of dams and catastrophic floods (Watkins & McKendry, 2015).
The rivers play a huge role in carbon sequestration. Huge drains of the basins of the main rivers are carried by phosphorus, iron and other nutrients far beyond the coast, where some forms of life absorb them live in the seas. These microorganisms fix carbon, taking it from the atmosphere. Tides are a renewable, reliable and predictable source of energy. The most effective and economically viable way to get energy with the help of a tidal hydroelectric power station is to operate two or more alternately, operating systems and they must have independent tanks. However, the costs of building tidal hydroelectric power plants are still significant. The construction of bottom turbines is complicated by the fact that the best places for their installation (areas of tidal currents) are in unreliable waters, in heavily indented banks (Kahia, Aïssa, & Lanouar, 2017).
Hence, tidal hydropower plants can have a negative impact on marine life and fauna. Large fish, turtles, and sea animals can die, falling under the turbine blades, and a particularly large catch of this kind can damage the turbine. Tidal power plants with dams represent the especial danger for marine inhabitants. A tidal dam creates a water reservoir outside the natural boundaries of the bay or estuary, changing its characteristics. This affects the turbidity of the water and the level of its sedimentation (sediment deposition at the bottom). Errors in the construction and operation of a tidal power plant can cause local flooding.
Current Technology To Overcome Energy Reliability And On-Demand
This chapter presents one of the limitations associated with the renewable energy and approaches, which are used to overcome the limitation. In addition to this, this chapter also presents the use of current technology in overcoming issues related to renewable energy.
Energy Reliability and On-demand: A Major Limitation
As described earlier, there are different limitations related to the renewable energy and one of these limitations is the energy reliability and on-demand supply of energy. Increasingly, the development of the renewable energy industry is gaining momentum. However, along with the unquestionable merits of energy derived from renewable sources, one important issue needs to be addressed before massively introducing and using alternative energy sources. This is the accumulation and storage of energy for its subsequent use and ensures reliability and on-demand supply of energy when required. Therefore, it is proposed to develop a concept for the accumulation and conservation of energy (Watkins & McKendry, 2015).
The transition to renewable electricity is technically complicated since solar and wind energy are not distributable. Further, wind turbines and solar panels cannot be connected to the grid so that coal and nuclear stations can fill up the load deficiencies as necessary as well as storage of hydroelectric power is also a key issue. The main problem is that a certain amount of electricity needed at a given time should be available at this time; otherwise, there will be an overvoltage and an outage of the network. This is the reason that it is important to adjust the level of output to the level of consumption (Kahia, Aïssa, & Lanouar, 2017).
A number of different options for the accumulation and storage of energy are implemented for this purpose and these include compressed air in underground caves, flywheels, hydropower, and batteries. Most importantly, it is planned to use natural gas as a temporary bridge to a gradual transition to biogas and hydrogen produced from surplus wind and solar energy. Wind and solar energy can be accumulated in the form of gas and used as motor fuel for heating or for the production of distributed energy. Further, with the help of smart energy systems, it is possible to adjust the demand for energy to the available reserves (Luthra et al., 2015).
The renewable energy storage is a limitation of renewable energy and therefore, it is imperative to ensure a stable supply of renewable electricity. Renewable energy from evenly distributed sources is a much milder approach to energy supply with much less impact on the environment. The reliability and on-demand supply problems can be solved using the technology of accumulation, and energy storage is part of a solution that allows you to accumulate energy from renewable sources for later use (Helms, Salm, & Wüstenhagen, 2015). Although batteries are most often used to store energy, the constant fluctuation of high voltages gradually reduces their capacity, which leads to a short service life of such devices. This, in turn, in the long term, causes an increase in costs for maintenance and replacement.
Supercapacitors are energy storage devices that are used today and that are designed to handle repetitive peak demand cycles and to provide energy backup during jumps to avoid shutdowns. They store energy in the form of an electric field, which allows them to function at a higher temperature range than the batteries and provides them with a faster response and high reliability in extreme situations (Luthra et al., 2015).
As an alternative to chemical batteries, flywheels accumulating energy in the form of kinetic energy of the rotating mass, providing a large number of charging cycles has been used. The durability of solutions of this type mitigates the cost of replacing equipment, and the composition of such devices quickly provides energy at critical moments. This allows companies to switch to alternative energy sources without jumps and outages. Keeping energy without using inefficient chemical technologies, allows energy companies to benefit from lower costs associated with renewable sources, and to save energy for those moments when it will be most needed (Larcher & Tarascon, 2015).
However, even under these conditions, the use of many technologies is required to solve various problems that arise when integrating renewable energy sources into electrical networks. Therefore, energy companies must evaluate which technologies can be used together to provide better performance and cost-effectiveness. Since renewable sources change the traditional approach in the work of energy companies, today it is necessary to study various solutions for the accumulation and storage of electricity in order to adapt them in the near future to the challenges that lie in the way of further development of the use of renewable energy (Helms, Salm, & Wüstenhagen, 2015).
The effective use of world energy resources depends not only on the methods of their use but also on the methods of storing the generated energy. This is because when placing a solar or wind power plant it is desirable to install also an energy storage system since electricity from renewable energy sources is generated unevenly throughout the day. For example, solar energy is produced only in the daytime, but it should be used throughout the day (Larcher & Tarascon, 2015), or there was an overcast day, and the generation was much less than the daily consumption of your household. It is for such cases that energy storage systems are designed.
Current Technology Available in Storage of Renewable Energy for Reliability and On-Demand
The possibility of accumulating electricity on an industrial scale is beneficial to all market participants, producers, suppliers, consumers and the regulators. The latest analytical reports have indicated a record amount of investment in projects to develop and create energy storage. In the developed countries, energy storage technologies are entering the stage of “pre-commercial” use. The main difference between the electric power industries from any other physical branch is the impossibility of storing the goods produced by it on an industrial scale. In each unit of time in this industry, only as much electricity as the consumer needs to be produced. To provide such an opportunity, either expensive reserve generating capacities or complex geographically distributed power systems are needed (Helms, Salm, & Wüstenhagen, 2015).
The operating mode of any power system is determined primarily by the degree of load on it from the consumers. As a rule, at night, electricity consumption is significantly reduced, and in the morning and in the evening – exceeds the level of daily consumption. Additionally, in general, regardless of the time of day, the electrical load is continuously changing. These constant fluctuations complicate the task of maintaining a balance between production and consumption and lead to the fact that generating capacities for a significant part of the timework in an economically non-optimal mode (Larcher & Tarascon, 2015).
There are three traditional types of power plants: nuclear, thermal (TPP) and hydroelectric power (HPP). NPPs do not regulate their workload for safety reasons. HPPs are much better for working with an uneven load schedule, but they are not in every power system, and if they are, they are not always in the required quantity. Thus, the main load to cover the unevenness of daily electricity consumption falls on TPPs. This, in turn, leads to their work in an uneconomical mode, increases fuel consumption and, as a consequence, the cost of electricity for consumers (Ellabban, Abu-Rub, & Blaabjerg, 2014).
The use of technology will allow optimising the process of electricity production by balancing the load schedule for the most expensive generating equipment, as well as saving the expensive thermal generation from the role of the regulator. In turn, this will inevitably lead to a reduction in hydrocarbon fuel costs, an increase in the utilisation rate of the installed capacity of power plants, will increase the reliability of energy supply and reduce the need for the construction of new facilities (Luthra, Kumar, Garg & Haleem, 2015). The technology-based accumulators allow creating an energy reserve without excessive operation of generating capacities, optimising the operation mode of power plants, ensuring a quiet passage of the night minimum and the daily maximum of the loads.
The effect of technological advancements for the storage of the renewable energy would bring benefits for consumers. The electricity becomes cheaper, the reliability of power supply increases, it is possible to ensure the operation of critical equipment in the event of a power failure and create a reserve for accidents. In addition, the effect for the power grid complex due to technology advancement would reduce the peak load on electrical substations and the costs of upgrading the network infrastructure, improve the quality and reliability of power supply to consumers (Yaqoot, Diwan, & Kandpal, 2016).
Now, one of the main trends of world energy is the development of renewable energy sources. Among the countries that develop green energy, Denmark is the most striking example, generating 140% of the national energy demand by RES, and Germany, where RES accounts for about 50% of the installed capacity of power plants (94 out of 182 GW), and this share continues unswervingly grow. At certain hours, RES can already provide up to 100% of the electricity demand. At the same time, both thermal and nuclear power plants have to perform a backup function, since the generation of renewable energy sources is not constant (Luthra, Kumar, Garg & Haleem, 2015). Electricity storage can become an outlet for continued successful integration of renewable energy sources into the energy systems of different countries. They will allow smooth fluctuations in the development of renewable energy sources and to align the load schedule.
Another trend is the development of distributed energy. Consumers want to minimise their costs and install their own generating sources (for example, solar panels or wind generators). In countries where the share of distributed generation is high, the problem arises of integrating such consumers into the market system. Since the consumer himself takes as much energy from his source as he needs at a given time, he may have surpluses. The problem of selling these surpluses to a network can be solved with the help of drives. In addition, they can also be used to create individual reserves. To date, 99% of the industrial accumulation and storage of electricity (about 132.2 GW) is provided by pumped storage power plants (PSPs) (Yaqoot, Diwan, & Kandpal, 2016). For the compressed air storage, sodium sulfide batteries and lithium rechargeable batteries are used. The most tested of the accumulators are PSPs and devices operating on compressed air technology. The remaining technologies are still in the process of development. At the same time, if devices that use compressed air technologies can store large amounts of electricity for several hours, they are sufficiently limited in terms of supplying large amounts of energy to support or counter various short-term fluctuations (Alotto, Guarnieri, & Moro, 2014).
With regard to batteries, the current cost estimates for their installation range from $200 to $800 per 1 KW of installed capacity. The lowest costs correspond to lead-acid batteries since they are at a higher stage of technological development. This range corresponds to the lower cost boundary for PSPs, but it is much lower than other potential and new storage technologies. However, the main disadvantage of lead-acid and other ABs is their low life expectancy compared to PSPs, which have much longer service lives (Luthra et al., 2015). The service life of the aircraft varies significantly depending on the frequency of application, the discharge rate and the number of deep discharge cycles.
The storage of electricity by the use of advanced technologies will significantly change the global economy. The cumulative average annual growth rate of the battery market of all types will be 18.7% over the next ten years: from $637 million in 2014 to $3.96 billion in 2025. The capacity of electric storage devices in the EU, US and China, according to different scenarios of the International Energy Agency, will increase from two to eight times by 2050. A new investment cycle in the energy sector is projected. The potential niche for new energy facilities is estimated at 15-30 GW. Investments can reach $500-700 billion by 2035 (Yaqoot, Diwan, & Kandpal, 2016). At the same time, almost all market participants will be able to benefit from the use of drives. Some of the technologies that are presently used or are being under development for the storage and on-demand supply of renewable energy are given below;
Pumped- Storage
Hydroelectricity can be stored by using different methods and these include the pumped storage and compressed air. The pumped storage power plants (PSPs) are most famous are mechanical ones approaches for storage of energy. Hydropower is essentially one of the types of mechanical energy, but it differs in that it can be accumulated in very large quantities and used at such power. Further, it can be used in such intervals that allow equalising the variable load of the power systems and ensuring a more even operation of thermal power plants (Alotto, Guarnieri, & Moro, 2014).
The pumped storage power plant includes two reservoirs (upper and lower), the difference in levels of which usually ranges from 50 to 500 meters. In the machine room, there are reversible units that can work both as engine-pumps and gas turbine generators. At a high-pressure (500 meters and more) separate pump and turbine units are used. At a time when the load of the power system is minimal (for example, at night), these aggregates fill the upper reservoir with water, and during the peak load, the systems convert the accumulated hydropower into electrical energy (Ma, Yang, & Lu, 2014).
The efficiency of such accumulation is equal to 70-85%, the cost of electricity received in this way is much higher than in thermal power plants. Yet, the alignment of the load schedule and the possibility of reducing the nominal capacity of thermal power plants reduce the operating costs of power systems and fully justify the construction of a hydroelectric power station. Currently, there are more than three hundred hydroelectric power stations in the world.
When the need for electricity is reduced, its surplus is used at the pumping plant to pump water from the lower reservoir to the upper one. Thus, the extra electrical energy is converted into mechanical (potential) energy. During the increased demand for electricity, the water from the upper reservoir to the lower one is discharged (Wang, Li, Liao, & Qin, 2017). At the same time, water flows through a hydro turbine generator, in which its potential energy is converted into electrical energy (Weitemeyer et al., 2015).
Compressed Air
Compressed air is another method used for storage of renewable energy. In spring mechanical drives, a large flow and energy input is provided by compression and straightening of the spring. The storage life of stored energy in a compressed spring can be many years. However, it should be borne in mind that under the influence of constant deformation, any material accumulates fatigue over time. Therefore, after a time, the compressed spring can be discharged completely or partially. The gas receiver is an air receiver. In this class of devices, energy is stored by the elasticity of the compressed gas. With excess energy, the compressor pumps gas into the cylinder. When it is required to use stored energy, the compressed gas is supplied to a turbine directly carrying out the necessary mechanical work or a rotating electric generator (Weitemeyer et al., 2015).
Gas, as compressed to a pressure of tens and hundreds of atmospheres, can provide a high specific density of stored energy for an almost unlimited time. However, the compressors with a turbine or a piston engine included in the installation are rather complicated devices with a limited resource. There are also accumulators using chemical energy (Ghalelou, Fakhri, A. Nojavan, Majidi, & Hatami, 2016). Chemical energy is energy stored in atoms of substances that is released or absorbed during chemical reactions between substances. It is either released in the form of heat during exothermic reactions (for example, burning of fuel), or it is converted into electrical in galvanic cells and batteries. These energy sources are characterised by high efficiency (up to 98%), but low capacity. Chemical storage of energy allows you to receive energy in the form from which it was stored, and in any other. However, it is not possible without special technologies and high-tech equipment (Budt, Wolf, Span, & Yan, 2016).
Flywheel Energy Storage
A flywheel is essentially a dynamic accumulator that accumulates energy mechanically in the form of the kinetic energy of mass rotation around the axis. The input electric current rotates the flywheel rotor and maintains its rotation 24 hours a day, 7 days a week, until the stored energy is released through a generator, such as a reactive synchronous motor. The available amount of electricity and duration are determined by the mass of the flywheel and its speed.
Until recently, mass-produced flywheels used the mass as an energy source and doubling the mass doubles the energy. However, the use of a large mass limits the maximum number of revolutions per minute. This restriction prevents a high energy density. Instead of using the mass as a primary energy source, some fly feels benefit from a high rotation speed. The higher the speed, the lower the mass required to obtain a given output energy. While doubling the mass leads to a doubling of the stored energy, doubling the speed increases the stored energy fourfold (Hongliang, Jiangwei, Honggang & Chao, 2017).
The idea of accumulating energy with the help of flywheels has been developing already in this century. They are made of composite materials having a huge number of layers and capable of withstanding high mechanical loads. The speed of rotation of the flywheel can reach 22000 rpm. Such a flywheel is located in a vacuum on special electromagnetic suspensions. The flywheel is untwisted in the presence of unused energy received from wind generators and solar batteries, accumulating it. Then, when the supply of energy ceases, it transfers energy to the generator that generates electricity. The developers consider this device promising and predict a great future for sustainable energy (Sebastián & Peña-Alzola, 2015).
The second type of mechanical battery is intended for transport devices. The principle of its operation is surprisingly simple. The battery of this type is a flywheel, which has a large mass and is untwisted to a very high speed. The energy stored by it is nothing more than the kinetic energy of the flywheel itself. To increase the kinetic energy of the flywheel it is necessary to increase its mass and the number of revolutions. However, with an increase in the number of revolutions, the centrifugal force increases, which can lead to rupture of the flywheel. Therefore, flywheels use the most durable materials, for example, steel and fibreglass. Flywheels have already been manufactured, the mass of which is measured by many tens of kilograms, and the speed of rotation reaches 200 thousand revolutions per minute (Hongliang et al., 2017).
Energy losses during rotation of the flywheel are caused by friction between the flywheel surface and air and friction in the bearings. To reduce losses, the flywheel is placed in a casing, from which air is evacuated, i.e., a vacuum is created inside the casing. The most advanced bearing designs are used. In these conditions, the annual energy loss of the flywheel can be less than 20%. Currently, prototypes of city buses have been created with an energy storage battery of this type. However, the prospect of using flywheels-batteries is still unclear (Chang, Li, Zhang, Wang, & Xue, 2015).
Gyroresonance energy storage devices are the same flywheel but made of an elastic material (for example, rubber). Energy is stored here in the resonant wave of elastic deformation of the flywheel material. With an operating flywheel speed of 7-8 thousand rpm, the stored energy was enough to allow the car to travel 1,500 kilometres to 30 kilometres with an ordinary flywheel of the same size (Sebastián & Peña-Alzola, 2015).
Poor quality of the supply network is a well-known problem. However, the key task is to ensure the reliability of power supply and the ability to maintain a sinusoidal wave when anomalies or disturbances appear in the input network. Normal, battery-based, uninterruptible power supplies (UPS systems) connected to a DC bus provide a smooth continuous power supply until the power supply network is restored or the backup engine takes no load after a few seconds. In a typical double conversion UPS, a battery chain is connected to the DC bus between the rectifier and the inverter. In most cases, it takes less than 10 seconds to fill the gap between the power failure from the mains (voltage failure in the AC bus) and the start of the generating set. The main obstacle is that the batteries can behave unpredictably (Chang et al., 2015). One faulty cell in the battery chain can make all the batteries inefficient.
Manufacturers of batteries claim that their specified lifespan, at least four years is realised only if they are kept at a constant temperature of 25 °C (which requires air conditioning) and are not subjected to excessive cycling, i.e. when they are not used. The flywheel with its exceptional reliability is an excellent replacement for batteries for industrial applications without a backup engine generator in cases where prolonged power outages are allowed. For applications that require high-quality power and for which continuous power is important, the ideal solution is to install the flywheel in conjunction with the UPS and the generator.
Alternatively, the flywheel can work in parallel with the batteries to amplify them or to increase their longevity. In this configuration, the flywheel absorbs all short-range anomalies and disturbances in the mains before they affect the batteries. This can be easily ensured by setting the adjustable voltage value of the flywheel DC bus above the battery discharge voltage. The effect on the batteries is by no means is unremarkable (Sebastián & Peña-Alzola, 2015). Fortunately, a power storage device built on a flywheel basis can mitigate this effect by significantly increasing the lifetime and reliability of the battery pack and drastically reducing the cost of their operation and maintenance.
The flywheel is relatively small, located inside the container approximately 60 centimetres in height and 46 centimetres in diameter. The magnetically levitated flywheel rotates in a vacuum at a speed of 54,000 rpm. The flywheel experiences practically no aerodynamic resistance inside the hermetically sealed primary container. When starting, the 52-pound flywheel/rotor shaft immediately starts levitating in the field of electromagnets located on top. Four other electromagnets (two on top and two from below) support the exact centring of the shaft and its perpendicularity. The asynchronous reactive 4-pole motor generator generates electricity (Sebastián & Peña-Alzola, 2015).
In standby mode, the system consumes only 300 watts, which is about 10 times less than the power consumption of the slow, heavy flywheels on the market. Batteries have disadvantages such as frequent and expensive maintenance; the need for an air conditioning system, in which there may be malfunctions and which requires additional costs; large footprint; large weight imposing restrictions on placement; slow charging; frequent replacement; second reserve chain “for insurance”; the complexity of recycling used batteries. Replacing the batteries with a flywheel eliminates all these factors (Chang, Li, Zhang, Wang, & Xue, 2015).
Gravitational Potential Energy Storage with Solid Masses
The gravitational force of the Earth, also called the force of gravity, is important, but the attraction that objects create among themselves can be neglected. This means that any object on our planet that has the ability to fall has a supply of potential energy and can do the work. It is not difficult to establish that the supply of potential energy is directly proportional to the mass of the object, and its height relative to the surface of the earth. Anybody raised to a certain height acquires a reserve of energy and stores it until the moment that body is thrown from the height and returned to the surface of the earth. The conclusion is simple; the body lifted above the ground can store energy reserves, being a gravitational accumulator. At the same time, the energy reserve does not decrease with time and does not become worthless. This is the basis of development of gravitational accumulator and this principle is used in case of the gravitational potential energy storage with solid masses (Ströhle, Haselbacher, Jovanovic, & Steinfeld, 2016).
In accumulators of this type, at the stage of energy storage, the load rises upwards, accumulating potential energy, and at the necessary moment, it is lowered back, returning this energy with advantage. Application as a load of solid bodies or liquids introduces its own characteristics in the design of each type. An intermediate position between them takes the use of granular substances (sand, lead shot, small steel balls, etc.).
The essence of gravitational mechanical storage is that a certain load rises to the altitude and at the right time is released, causing the generator axis to rotate along the way. At a time when solar panels and windmills produce a lot of energy, special heavy wagons are driven by electric motors to the mountain. At night and in the evening, when energy sources are not enough to supply consumers, the cars go down, and the motors, working as generators, return the accumulated energy back to the grid. Virtually all mechanical drives of this class have a very simple design, and therefore high reliability and long service life (Ströhle, Haselbacher, Jovanovic, & Steinfeld, 2016). The storage time of the once stored energy is practically unlimited unless the cargo and structural elements with time will not crumble from old age or corrosion.
The energy stored when lifting solids can be released in a very short time. The limitation on the power received from such devices is imposed only by the acceleration of free fall, which determines the maximum rate of increase in the speed of the falling cargo.
Unfortunately, the specific energy intensity of such devices is small and is determined by the classical formula E = mgh. Thus, in order to store energy for heating 1 litre of water from 20 ° ? to 100 ° ?, it is necessary to raise a ton of cargo at least to a height of 35 meters (or 10 tons to 3.5 meters). Therefore, when there is a need to store more energy, this immediately leads to the necessity of creating bulky and, as an inevitable consequence, expensive structures. The disadvantage of such systems is also the fact that the way in which the cargo moves is free and straightforward, and it is also necessary to exclude the possibility of accidental falling into this area of things, people and animals (Ströhle, Haselbacher, Jovanovic, & Steinfeld, 2016).
Latent Heat Thermal Energy Storage
When solar energy is considered, photovoltaic solar panels are considered, which convert the energy of the sun’s rays directly into electrical energy. However, there is another type of solar power station, in which acres of areas covered with mirrors reflect sunlight on special towers and this method is Latent heat thermal energy storage. Concentrated sunlight turns to water in these towers into superheated steam, which rotates the turbine with a generator that generates electricity. However, in both cases, there are some problems associated with the excessive amount of energy generated during the maximum intensity of sunlight, with the need to store this energy and its recoil at times of peak consumption. Engineers and scientists have found a universal solution to the above problems; they have developed a system of thermochemical storage of thermal energy, whose work is based on the use of chemical transformations, not electricity (Lane, 2018).
During the charging of the thermochemical battery under the influence of high temperature, strontium carbonate decomposes into strontium oxide and carbon dioxide, which consumes the thermal energy of the rays of sunlight. The discharge of this battery consists of the reverse reaction of strontium oxide with carbon dioxide, because of which virtually all of the previously absorbed thermal energy is released (Chaichan, Kamel, & Al-Ajeely, 2015).
All materials used in this technology are non-combustible, environmentally safe and easily accessible. In comparison with other similar systems, the system based on strontium carbonate is capable of providing a 10-per cent increase in the density of energy storage. However, the most important advantage of the new system is that, unlike similar systems that use other substances and other chemical reactions, it can operate at temperatures up to 1200 degrees Celsius. Other systems are able to work only at 600 degrees and this causes an almost twofold increase in the efficiency of the new system (Lane, 2018).
The operating temperature of the system is so high that it can first heat the air that will rotate the primary circuit turbine, and the residual thermal energy of the air can turn the water into superheated steam that will rotate the second turbine. Studies carried out in the laboratory showed that the energy capacity of the thermochemical accumulator begins to decrease sensitively after 45 cycles. The reason for this is structural changes in the materials used and the researchers solve this problem by developing methods for intermediate processing and restoration of working materials (Lane, 2018).
Rechargeable and Electrochemical Batteries
For the compressed air storage, sodium sulfide batteries and lithium rechargeable batteries are used. The most tested of the accumulators are PSPs and devices operating on compressed air technology. The remaining technologies are still in the process of development. At the same time, if devices that use compressed air technologies can store large amounts of electricity for several hours, they are sufficiently limited in terms of supplying large amounts of energy to support or counter various short-term fluctuations.
With regard to batteries, the current cost estimates for their installation range from $ 200 to $800 per 1KW of installed capacity. The lowest costs correspond to lead-acid batteries since they are at a higher stage of technological development. This range corresponds to the lower cost boundary for PSPs, but it is much lower than other potential and new storage technologies. However, the main disadvantage of lead-acid and other ABs is their low life expectancy compared to PSPs, which have much longer service lives. The service life of the aircraft varies significantly depending on the frequency of application, the discharge rate and the number of deep discharge cycles (Xu et al., 2014).
The energy accumulators, such as electrochemical batteries are extensively used. An electrochemical battery is charged (accumulates energy) by feeding it with electrical energy. In the battery, it is converted into chemical energy. Gives out the same electrochemical accumulator accumulated energy again in the form of electrical energy.
The battery of this type has two electrodes – positive and negative, immersed in the solution – electrolyte. The conversion of chemical energy into electrical energy occurs through a chemical reaction. To give the beginning of the reaction, it is enough to close the outside of the battery’s electrical circuit. On the negative electrode containing the reducing agent, the oxidation process occurs because of the chemical reaction. The free electrons that are formed in this case pass along the external portion of the electric circuit from the negative electrode to the positive electrode. In other words, a potential difference arises between the electrodes, creating an electric current (Xu et al., 2014).
When charging the battery, the chemical reaction proceeds in the opposite direction. Electrochemical batteries have become very widespread mainly when starting internal combustion engines. At present, comparatively cheap lead-acid batteries are most used. However, recently, powerful lithium-ion batteries began to be used on hybrid cars and electric cars. In addition to lower weight and greater specific capacity, they allow almost completely using their nominal capacity, are considered more reliable and have a longer service life. The main drawback of all existing electrochemical batteries is the low value of the specific energy stored by the battery.
In general, the problem of efficient accumulation of energy generated, including from renewable energy sources, is now one of the most complex issues of energy. Of course, the introduction of batteries will make the power supply more reliable; will allow it to be reserved. With the help of rechargeable devices, it is possible to ensure equalisation of the pulsating power generated by the generating unit in conditions, for example, of the ever-changing wind speed. Harmonisation of production and consumption schedules for the purpose of powering consumers during periods when the unit is not working, or its capacity is insufficient and increase in the total generation of energy by the generating unit are other benefits achieved by the use of rechargeable batteries (Acerce, Voiry, & Chhowalla, 2015).
Super-Capacitor
The supercapacitor is a new energy storage device and a current source that occupies an intermediate position between battery cells and traditional capacitors in its technical characteristics. Distinctive features of supercapacitors are high power, the ability to quickly give and accumulate energy, resistance to unfavourable environmental factors, durability, operational reliability and environmental friendliness. Recently supercapacitors around the world have played an increasing role; the growth rate of the supercapacitor market is 30-40% per year. The applications of supercapacitors are constantly expanding, finding new applications in all industries, from consumer electronics, mobile phones, and computers to hybrid transport, Smart Grid systems and space technologies (Acerce, Voiry, & Chhowalla, 2015).
Super-capacitors take their place in quality energy systems for industry and telecommunications, as well as in the renewable energy industry. The use of supercapacitors in devices and systems has already become not only a technical necessity but also a symbol of innovation and modernity of applied devices, technologies and systems. The most attractive from a commercial point of view are capacitors with a double electric layer (DES), or as they are called EDLC (Electric Double-Layer Capacitor), which have an unusually high energy density compared to conventional capacitors. Compared to rechargeable batteries, supercapacitors have tens of times more power and a much longer life. These are the two main reasons why engineers are increasingly choosing supercapacitors for various applications. Supercapacitors DESs are energy storage devices that can replace conventional capacitors or batteries in many applications where more power is required than conventional capacitors and/or high power and a long service life that cannot be provided by rechargeable batteries (Dubal, Ayyad, Ruiz, & Gomez-Romero, 2015).
DES are two inactive high-porous carbon electrodes and a current collector immersed in an electrolyte with a certain voltage potential. In the cell of the DEL capacitor, the positive electrode potential attracts negatively charged ions, while the same potential on the negative electrode attracts positively charged ions. The separator does not allow the electrodes to create a short circuit. A large amount of energy that the DPP can store is achieved due to the huge surface area provided by porous carbon electrodes (Liao, Li, Jin, Yang, & Wang, 2015).
The accumulation of energy in the DES is a physical and reversible process with minimal losses, which determines the long service life of the DES and their enormous cyclical resource. Since the rate of charge and discharge depends solely on the physical movement of ions, the DEL can accumulate and give up energy much faster than the battery cells in which the process is directly dependent on slow chemical reactions. The same is due to the possibility of DES to issue orders of magnitude higher power than the batteries (Liao, Li, Jin, Yang, & Wang, 2015).
The application of double-layer capacitors (Electric Double Layer Capacitor) in the technologically advanced countries of the world is steadily growing. This is because the use of supercapacitors in many cases makes it possible to implement more effective, environmentally and economically sound solutions. In some cases, it allows moving to a fundamentally new technical and technological level (Wang et al., 2015).
The distinguishing features of supercapacitors are that these are highly specific power, which makes supercapacitors an optimal tool for working with sudden and significant changes in power and effectively used to stabilise the current parameters. In addition, high charge/discharge rate, which makes it possible to effectively use supercapacitors in energy recovery systems and pulse power compensation. A wide range of operating temperatures from -40 to 65 °C is tolerable, which ensures their use in various street systems without special climate systems. The service life is not less than 10 years (a million charge/discharge cycles), which eliminates the need for frequent replacements and reduces operational costs. Tightness and environmental friendliness are other benefits, which eliminates the need for operational costs and costs of conducting environmental activities. Compactness, small size, and weight are some properties, which makes supercapacitors effective for autonomous and mobile applications.
The use of supercapacitors in many cases makes it possible to implement more efficient, environmentally and economically sound solutions, and in some cases to shift to a fundamentally new technical and technological level. The main consumers of supercapacitors in the world are European countries, the United States and Asian countries, such as China, Japan, and South Korea. Supercapacitors are currently used in almost all industries, but the main consumers include electronics, transport, energy, including renewable and power equipment.
The use of supercapacitors in renewable energy is actually due to its initial instability, especially if we are talking about wind generators or solar batteries. In order to ensure the quality and stability of the electricity generated by end-users, and to integrate renewable energy sources into unified distribution networks, expensive measures are required. In this case, the use of supercapacitors becomes an effective alternative to traditional solutions. One of the most common applications of supercapacitors is their use as a part of the control systems for rotating turbine blades for wind turbines in order to maximise the generation of electricity and prevent blade breakage at high wind speeds, the so-called Pitch control systems (Wang et al., 2015).
The hydraulic and electrical systems have been used, while the latter are increasingly used because of their environmental friendliness and lower operating costs. At present, about 30% of the wind generators in the world are equipped with supercapacitors. These provide the impulse power required for turning the blades, stabilising the parameters and maintaining the power supply for the time of short-term voltage drops, as well as the safe and correct orientation of the blades.
Another common application is the use of supercapacitors as part of hybrid energy storage systems in conjunction with battery packs. In these systems, supercapacitors and accumulators compensate for each other shortcomings. Rechargeable batteries are used as the main energy storage, while supercapacitors provide pulse modes of operation, compensating for the unstable generation of renewable energy sources and rapid changes in load. In addition, supercapacitors protect the batteries from voltage drops and high charge/discharge currents. At the same time, the need for rechargeable batteries can be reduced by a factor of five, and the battery life is increased to two times (Wang et al., 2015).
Hybrid storage systems in many cases are the most effective solution for integrating renewable energy sources into distribution networks, compensating for the impulse load power, accumulating energy recovery, etc., which already has many practical confirmations. It should also be noted the effectiveness of the application of supercapacitors for autonomous power systems, confirmed by research and practice, where the main or only sources of energy are renewable sources or diesel generators (Alsharif, Kim, & Kim, 2018).
Autonomous systems make sense to use in cases where the main sources of electrical energy are so far from the road. The equipment of the road infrastructure that the laying of cable networks for load power is relatively more expensive when there is a need for the temporary provision of electricity. For example, in the cases of construction and repair of roads and when it is necessary to provide a long service life (10 years) in an autonomous mode in a wide temperature ranges (from -40 to +65 ° C) without the need for frequent maintenance and replacements.
Supercapacitors used independently or as part of hybrid energy storage systems, are an effective solution in the construction of autonomous power supply systems. For instance, for filling stations, collection points for tolls on toll roads, emergency telephones, parks, CCTV cameras, and communication and data transmission systems. The use of solar cells in conjunction with supercapacitors as energy storage devices can effectively organise road lighting and mark, lighting road signs and signs, etc. (Alsharif, Kim, & Kim, 2018).
The studies and practical world experiences show that in most cases the use of supercapacitors at all stages, from the generation of electricity by renewable energy sources to final consumers, is the most effective solution from the technical point of view and at the total cost of ownership and environmental friendliness. It would be advisable that the developers and creators of these solutions take into account the already accumulated world experience and consider the use of supercapacitors as one of the alternatives, which in many cases can be the most effective solution (Wang, Palazoglu & El-Farra, 2015).
Power to Gas Conversion
The production of electricity from natural gas is today the most common way of generating electricity and the reverse process is studied nowadays for the storage of energy to meet the demands and make renewable energy a reliable source. Power to gas (gas production) is one of the ways to store electricity generated by renewable sources – solar and wind power plants. Green stations produce electricity when there are natural conditions i.e. the sun is shining, or the wind is blowing. If there is a lot of renewable energy in the energy balance, there can be a situation of excessive output, which must either be balanced or accumulated. At the same time, now there are no batteries in the world that can store hundreds of megawatts of power efficiently and economically (Twidell & Weir, 2015).
The process of obtaining synthetic gas from electricity consists of two stages. First, electrolysis is used. Under the action of a constant electric current, the water decomposes into oxygen and hydrogen. After that, hydrogen is mixed with carbon dioxide. With the help of a special process, a mixture of gases in the presence of a catalyst is converted into synthetic methane. The obtained methane can be pumped into the gas pipe and transported directly to the consumer with the help of the existing gas pipeline infrastructure (Twidell & Weir, 2015).
There are other methods of converting energy into gas. In both cases, electricity is also converted to hydrogen. However, in the first, hydrogen is immediately pumped into the gas pipe or sent to the consumer, where it can be used, for example, in fuel cells to generate electricity. In the second case, the hydrogen obtained is mixed with biogas, thereby improving its energy properties. E-Gas plant functions in conjunction with a biogas plant and, in fact, serves to enrich the biogas received there (Wang, Palazoglu & El-Farra, 2015).
The scientists note that batteries, which are the standard form of storage, have limited potential and short life-cycle duration. In addition, systems based on electrochemical batteries cannot provide enough power to cover peak loads of national energy systems. In this regard, this approach for storage of renewable energy is under testing and it is estimated that the advancement in this context would result in the introduction of the different method of conversion of electricity into gas for later use at very low cost (Götz et al., 2016).
Discussion, Future Works And Conclusion
This chapter presents a precise discussion of the research to derive the concluding remarks for the research. This chapter provides a brief description of the objective of the project and the findings of evidence-based studies regarding renewable energy also putting forward the future works that could still be carried out on the subject matter so as to give a robust and detail information about the challenges within the renewable energy sector and solving them for a better greener future.
Discussion
The project was based on proposing a solution to how energy can be readily available with the use of a renewable energy source. As it is known, renewable energy is not really generated in large quantities and it could be affected by weather conditions, which may result in some challenges of on-demand with energy supply. In this regard, the focus of this research was to present the limitations of renewable energy resources and overcome different barriers and limitations associated with renewable energy.
The use of fossil fuels to produce energy in a generalised way came from the hand of the Industrial Revolution (17th century) and the steam engines, with their external combustion engines. The exhaustibility of these sources has a negative environmental impact caused by their consumption. Due to the higher construction cost required for the renewable projects, these projects are considered as risky and it is usually harder for developers or utilities to justify the investment made on these projects. This is the reason that irrespective of different risks associated with the use of fossil fuels these fuels are still used.
The energy source for consumption mainly includes combustible (fuel), which include the energy of technological processes of chemical and thermochemical processing of raw materials, namely combustible gases, solid and liquid fuel resources, which are not suitable for further technological changes. This is the reason that it is important to look for alternative and renewable sources of energy that guarantee reliable, non-polluting and sustainable energy services for all inhabitants of the planet.
The main issue is the storage of energy that can meet the demand for energy. The world has to stop its reliance on fossil fuel for a sustainable future as the fossil fuels have been the cornerstone of the industrial revolution and have been able to provide energy on demand for the world for many decades. It is a matter of fact that the raw materials need for energy generation is readily available and could be used to produce energy quantities as required to meet demand. However, it effects on the climate and the environment coupled with the price changes on the international market for fossil fuels have led to expect to call for a change in the way we generate energy if we are to protect our environment.
The current energy industry needs efficient and inexpensive technologies to store and store clean energy that will help us get rid of fossil fuels in the future. The effective use of world energy resources depends not only on the methods of their use but also on the methods of storing the generated energy. This is because when placing a solar or wind power plant it is desirable to install also an energy storage system since electricity from renewable energy sources is generated unevenly throughout the day. For example, solar energy is produced only in the daytime, but it should be used throughout the day.
Future Works
There is a need for carrying out further evidence-based research studies focused on some other research objectives. More effort should be carried out to demonstrate the ways to develop and increase storage capacity to meet the challenges of reliability and energy on demand with renewable energy going into the greener future. It is also important that some future work must be carried out to identify and present set of recommendations, policies and techniques that should be easier to implement and adapt by the government and the general population to ensure a greener environment. The extensive research studies must be carried out in other aspects such as the concept of using renewable homes so as to present a clear solution to the problems. Further studies are required to present the solution in the form of a clear set of initiatives that the government can implement and also to develop less costly for the wider population to implement. The focus of the future studies would be on the role of renewable homes in reducing the carbon emissions. These studies would be focused on determination of the role of these home in sustainability as well as reduce carbon footprints due to emission. The future work would also consider extensive information for the promotion of the use of renewable energy by the local population for a greener future at a wider level.
Conclusion
It is not possible to make use of renewable energy the way that the use of non-renewable energy is eliminated. The technology would have to be developed to create a device that consumes less energy and that everyone would have to learn and understand the principles of energy management. However, the technology is associated with some limitations and there is a need for further advancements to bring positive changes and decrease carbon footprints of excessive use of fossil fuels.
Increasing energy efficiency has always been a determining factor in the development of energy. To date, innovative technologies have been developed that optimise the use of fossil fuels and renewable sources, as well as generated electricity. However, this is not enough to meet the ever-growing energy needs. The energy system of the future should produce much less greenhouse gas emissions. To achieve this goal, it is necessary to increase the share of renewable sources, cope with fluctuations in electricity generation and the growing decentralisation of its production. This will require the consolidation of technologies and the unification of efforts of numerous market operators, which will help to form an integrated energy supply system with new business models. Thus, in addition to improving each component of the equipment along the entire energy conversion chain, digitalisation will continue to be key to maintain stable operation and ensuring the sustainable development of the energy system and its individual parts.
The major challenges and constraints to access renewable energy can be overcome by increasing awareness of different nations about the benefits of renewable energy and its role in the reduction of the carbon emissions. The outcomes of this research have revealed that the major barrier to the use of renewable energy is the reliability and supply of energy and for this purpose, there is the need for efficient storage methods. Different storage methods like hydroelectricity, pumped-storage, super capacitor rechargeable batteries, flywheel energy storage, latent heat thermal energy are effective to overcome the storage issues and meet the needs of energy.
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