Chapter 1: Renewable Energy Analysis and Resources Free

According to the definition of the International Energy Agency (IEA), “renewable energy is the energy that is derived from natural processes that are constantly replenished such as solar, wind, biomass, geothermal, hydropower, ocean resources, electricity and hydrogen derived from those renewable resources” (OECD, 2014). One of the most critical issues in building sustainable energy solutions is to handle the energy trilemma, which is based on three dimensions: the security of energy supplies, affordable energy sources, and reducing carbon emissions to sustain the environment (Bale et al., 2015). The increased consumption of different types of energy, including fossil fuel sources to supply the essential services for humans like lighting and heating, has caused not just genuine climatic changes but also an energy-security problem in case of sudden energy cuts, which may influence human existence negatively and risk the eventual fate of next generations. Fundamentally, the solid admittance to different kinds of energy consistently and in satisfactory sums and normal costs that do not negatively sway the climate and the economy is regularly considered the energy security definition (Zhu et al., 2020a). On 11 December 1997, delegates from around the world gathered in Kyoto, Japan, to sign the Kyoto Protocol. This agreement set in motion the policy of the United Nations to combat climate change by limiting CO₂ emissions. While the agreement was approved in 1997, it did not take effect until 2005. The added focus on climate change has contributed to an international focus on reducing CO₂ emissions from electricity production. In 2019, IRENA published the Global Energy Transformation: A Roadmap to 2050. According to the 2019 edition, the share of the renewable energy in the world's total energy consumption must be scaled up a minimum of six times faster for the planet to satisfy the decarbonization and climate mitigation objectives set out in the Paris Agreement (International Renewable Energy Agency, 2019). Figure 1.1 represents the key milestones over the past 20 years in renewables from 1997 to 2019. A worldwide energy transition is urgently required to restrict worldwide surface temperature increase under 2 °C. Thus, successful transformation is determined to be possible; it will require the fast advent of policies to apply coordinated initiatives for integrating worldwide issues, like climate change, into national and local policy concerns. One hundred and ninety-three nations authorized the sustainable development goals (SDGs) in September 2015. This is formally called the 2030 Agenda for Global Development of SDGs, including developing and developed nations. Energy and power are crucial demands of every country, and their importance has emerged in the energy industry, including transportation (Ahmad and Zhang, 2020). Nations outside of the Organisation for Economic Co-operation and Development (OECD) are anticipated to represent 64.0% of 739 quadrillion Btu of the overall world by 2040.

The shift in the share of production of the whole gross domestic output results in more considerable energy requirements and usage variations. Asia is forecasted to be the biggest shift in energy usage in non-OECD nations. In contrast, China's development results in a boost in the percentage of energy-intensive products produced worldwide. India's per capita earnings and energy requirements continue to lag in the different bigger economies (Capuano, 2018). Gas levels of the greenhouse that contains many of them, including carbon dioxide, have risen considerably worldwide, which empowered governments and ventures to consider an alternative to environmentally harmful fossil fuels (Alkan and Albayrak, 2020). CO₂, CH₄, and N₂O are the three well-mixed atmospheric greenhouse gases (GHGs) that contribute most to the current global warming, as shown in Fig. 1.2. Since the beginning of the industrial period (1861–1880), their concentrations have risen, causing much of the current temperature to rise above the average global temperature. The 2 °C allowed temperature rise limit above the Paris Agreement's average for 2100 requires a significant reduction in GHG emissions over the next few decades (World Meteorological Organization and Global Atmosphere Watch, 2019). The most significant anthropogenic GHG emission in the atmosphere is carbon dioxide (CO₂), contributing to about 66% of the radiative forcing of long-lived greenhouse gases (LLGHGs). Over the past decade, it was responsible for about 82% of the rise in radiative forcing and about 81% increase over the past five years. On the other hand, approximately 17% of LLGHGs radiative forcing leads to methane (CH₄). Natural sources release about 40% of methane into the atmosphere like termites and wetlands, whereas 60% originates from anthropogenic sources like fossil fuel exploitation, rice agriculture, cattle farming, biomass burning, and landfills (Marielle Saunois et al., 2019). The third most significant GHG emission is nitrous oxide (N₂O). Around 6% of radiative forcing by LLGHGs comes from it. N₂O is released from natural (about 60%) and anthropogenic (about 40%) sources into the atmosphere, including soils, oceans, biomass burning, the use of fertilizers, and different industrial processes.

One hundred and twenty-six nations around the globe have renewable energy policies that incorporate a wide assortment of innovations and sources. These policies range from direct investments, codes, tariffs, grants, strategic, plans, regulatory instruments, and financial incentives and are executed dominatingly at the public and state levels. While arrangements between nations differ regarding the advances they incorporate, fusing the broadest scope of advancements in our investigation gives the most preparatory gauge of conceivable ecological equity suggestions. In our concise audit of the IEA approaching their information base (842 arrangements), all in all, U.S. state-level RPSs are the generally comprehensive of the broadest scope of renewable energy innovations and technologies (Levenda et al., 2021).

There are many renewable energy sources (RESs) such as sunlight, wind, geothermal, biogas, biomass, waves, tides, and ocean currents. Renewable energy technologies receive heat, power, or mechanical energy and transform them to motive power or electricity. Efficient activities should be started quickly to reduce the negative ecological impacts of climate change and global warming problems, just as productive and economical RESs should be investigated. The cost of electricity from RESs has gradually decreased over the last few years, as per the IRENA report (International Renewable Energy Agency, 2018). As per the statistics delivered by BP (BP, 2020) in Fig. 1.3, since 2009, the total worldwide energy consumption has kept expanding with a cumulative increment of 15.10% in 10 years. The consumption growth rate in 2017 has been growing for two successive years, arriving at the most significant development rate since 2013, which was higher than the regular annual growth rate over the previous decade. The consumption of renewable energy has kept on developing emphatically. In 2017, the worldwide renewable energy consumption grew at a yearly pace of 5.62%, which was 2.95 times higher than the annual development pace of essential energy consumption. Among them, hydropower development was moderately lethargic, with a development pace of just 0.56%. Other renewable energy source's development pace was as high as 16.64%, which was around multiple times higher than the yearly development pace of fossil energy consumption, demonstrating a solid development pattern. In 2017, the absolute worldwide renewable energy consumption was 58.84 EJ. The expansion was somewhat lower than in 2016 yet over the ten-year normal, and the complete growth in the ten-year term was about 62.98%.

The portion of renewable energy consumption has expanded consistently, increasing 41.59% from ten years ago (Li et al., 2020a). Renewable energy sources have acquired expanding consideration of governments around the globe due to the favorable circumstances they have over fossil fuels. Consequently, renewable energy strategies with clear objectives worldwide are being created and executed to encourage the development of the renewable energy field. The European Union (EU) directive on renewable energy requires that not less than 20% of the overall generated energy of the EU should be generated from renewable energy sources by 2020 (Aboagye et al., 2021). There are different motivations to redirect toward RESs, including a decline in the expenses of energy production from RESs, a decrease in carbon emissions, the reliability of the renewable energy technologies, and the unique nature of this industry. The cost of electricity from photovoltaic (PV) cells dropped by right around 3/4 in the time frame between 2010 and 2017 while wind turbine costs have diminished by about half in an equivalent time span, which prompts less expensive wind energy (Hannan et al., 2020). As shown in Fig. 1.4, the global composition of renewable power capacity was shifted during 2018. Hydropower was no longer accounted for half of the total renewable power capacity, hence falling below 48% by the end of 2018. On the other hand, wind power comprises 25% of the installed renewable power generation capacity, and solar PV exceeded 20% for the first time. Overall, renewable energy has grown to account for more than 33% of the world's total power generating capacity (REN21, 2019).

Photovoltaic (PV) technology can be categorized into three generations. First-generation technology is based on silicon such as monocrystalline, polycrystalline, and ribbon sheets. Second-generation technology is based on thin films such as amorphous silicon, cadmium-telluride (CdTe), copper indium gallium diselenide (CIGS), and multi-junction cells.

Third-generation technology is an emerging one that uses perovskite, passivated emitter and rear cells (PERCs), and nanocrystalline films. According to a study done in 2014 by Ramanujam et al. (2016), the market share of polycrystalline was 56%, and 36% for the monocrystalline-based solar cell was predominant. The rest distributed as 5% for CdTe and 2% for CIGS, and less than 1% for amorphous silicon. Different types of nanomaterials have been used in developing photovoltaic solar cells such as TiO₂ (Elsaeedy et al., 2021), ZnO (Abood et al., 2021), SnO₂ (Qureshi et al., 2021), Rh₂MnZ (Mentefa et al., 2021), CdS (Al-Douri et al., 2019), CuInS₂ (Alalousi et al., 2021), and metal oxides (Abu Odeh and Al-Douri, 2020) to enhance their efficiency and reduce the production costs of the generated electricity. Perovskite-based solar cells have been used, and different emissions might be released into the environment either directly or indirectly as a result (Kwak et al., 2020). There are four major components of any solar system: the cells, batteries, inverter, and the attached load. These solar components should be selected according to the cost, size, and application. The solar system design should consider the capacity of the required generated energy, economic feasibility, and reliability. Since PV system batteries are charged and discharged very often, higher capacity batteries are recommended. There are different types of batteries, such as valve-controlled and flooded batteries. Flooded batteries require more maintenance, so they can last longer, whereas valve-controlled batteries need less maintenance. Another critical part of the solar system is the inverter. There are many types available, but not all of them are suited to PV systems. When the power conversion efficiency of the PV inverter is low, the power produced by the PV array cannot be effectively supplied to the utility. To increase the efficiency of power, it is very important to use well-designed circuit technology to eliminate the switching and conductive losses of semiconductor devices as well as the power losses incurred by the interconnection of cables. In fact, several studies suggest improving the reliability of PV systems by optimizing the output capacity of the systems (Al-Shahri et al., 2021). Stropnik and Stritih (2016) increased the photovoltaic panel's power output and electrical efficiency using the phase change material (PCM) of RT28HC. Adding PCM material enhanced the performance by 14%. A few research studies have focused on using geospatial technology to analyze solar energy potentials and determine suitable locations for installations (Chiemelu et al., 2021). Solar irradiance is a critical piece of data for such geographical solar energy investigations. Obtaining this for a big region via typical field observation methods is frequently time-consuming and costly. However, ways for obtaining them from certain satellite photos have been created. Previous research (such as Hammer et al., 2003) utilized satellite photos to calculate surface solar irradiance using the HELIOSAT approach. Huang et al. (2019) conducted a review of the different methodologies and advances achieved in calculating surface solar irradiance using remote sensing (RS) satellite photos. There are many geospatial techniques to find the optimal and best place for creating a solar power park to identify suitable locations. Slope analysis, land use, land cover categorization, and site climatic variables to conduct site suitability analysis can be used. Chaves and Bahill (2010) created an algorithm that uses six basic inputs to locate ideal places for solar panel installations: the digital elevation model (DEM), aspect, slope, radiation, bare earth properties, and some mask. Geospatial technologies such as Geographic Information System (GIS) and remote sensing (RS) have shown to be useful in the assessment of renewable energy resources across the world. GIS applications have been utilized to give critical information for decision-making in a variety of study fields, including natural resource management, environmental pollution and hazard reduction, regional planning, urban development, and utilities management (Zhu et al., 2020b). The application of geospatial approaches for environmental modification, such as site selection, often entails the integration of many environmental variables or factors to incorporate numerous variables utilized in multi-criteria analysis; geoprocessing tools such as ArcGIS Model Builder are typically employed (Ebistu and Minale, 2013). Ganiyu et al. concluded that a typical PV system consists of the following basic components: (i) PV solar array collectors, (ii) power conditioners, (iii) energy storage system, and (iv) solar inverters. PV arrays convert solar energy from sunlight to direct current electricity, and the conversion rate is determined by insolation. A blocking diode placed immediately after the arrays ensures that the array generated power goes exclusively to the power conditioner and reduces the backward flow of electricity that may occur during low insolation when the battery discharges back to the solar array. The power conditioner is made up of a maximum power point tracker (MPPT), a battery charger, and a discharger controller. The MPPT ensures that the maximum power generated by the PV array is extracted at all times, whereas the charge–discharge controller acts as a charge regulator, preventing over-charging and over-discharging of the energy storage bank (batteries) required to store the electricity generated by the PV array conditioner (Ganiyu et al., 2020).

Until recently, the United States was the world's greatest user of energy, but China has just overtaken U.S. consumption levels. Because of the volume and worldwide effect of U.S. energy use and parallels in political influence on energy policy, the findings of this research are of worldwide relevance. Despite the fact that the U.S. government began supporting wind energy in 1978, the great bulk of wind energy growth has happened in the twenty-first century (Brown et al., 2012). Only four years from 2000 to 2004 had annual capacity increases of less than 10%, while from 2005 to 2009, U.S. wind power capacity rose at a 39% annual pace (Lu et al., 2011). In recent decades, wind power has been widespread across the world for the production of electricity. By the end of 2020, global cumulative wind power installations are expected to hit 741.7 GW. According to the World Energy Outlook 2019, the increase of generation from wind and solar PV assists renewables in overtaking coal in power generating mix in the mid-2020s. As shown in Fig. 1.5, low-carbon sources will account for more than half of total power generation by 2040, with wind and solar PV leading the way (IEA, 2020). Technically, the estimation of wind energy resources is necessary for calculating the annual output of electrical energy from wind energy at different locations.

Accurate records of typical wind speeds and their predictive characteristics are critical for estimating the capacity of wind energy. In general, wind energy worldwide can be classified into two types: onshore wind and offshore wind. As a result, wind power production is made up of inland and offshore wind turbines. To date, much of the wind power has been provided by onshore wind turbines (Li et al., 2020b). As the wind is becoming an increasingly significant and efficient source of energy production in many power markets, policymakers need to negotiate wind energy prices based on transparent and accurate statistics. The price dilemma is compounded by the variety of wind technologies, asset management strategies, and differences in international project cost estimates. Increasing wind power impacts wholesale electricity prices in many countries and contributes to shifts in the value of wind energy itself (Duffy et al., 2020). Connections between wind farms and the current electricity system are frequently disregarded. Because many wind farms are located distant from the population areas that consume the electricity, energy grid connectivity is a key challenge. To be linked to the current power grid, wind energy growth necessitates a considerable investment in high-voltage transmission lines (Lesser, 2013). Additional study on wind energy transmission lines financial costs and environmental impacts would be beneficial to the renewable energy profession (Dorrell and Lee, 2020). Although the CO₂ reduction advantages of wind energy are obviously beneficial compared to traditional fossil fuels, it is equally crucial to examine the negative environmental externalities associated with wind farms (Kreuter et al., 2016). Landscape degradation and habitat degradation, as well as noise pollution, have all been mentioned in previous research studies as detrimental environmental consequences (Zerrahn, 2017). Researchers have looked into adverse economic effects such as potential market distortions and energy excess storage challenges (Green and Vasilakos, 2010). Hydro-wind hybrid power generation has shown to be one of the viable, clean power generating options given water and wind energy properties. As an adjustable and energy source, hydropower can firm wind power, balance wind deviation by providing significant spare capacity and flexibility, decrease anticipated and real wind production discrepancies, and smooth wind power output. Furthermore, the distribution of hydro- and wind energy in time is governed by the law of low rainfall and windy weather in winter and spring and slight wind and heavy rain in summer and autumn. In this approach, wind and hydroenergy complement each other better in time. When the wind power generation fluctuates in the hydrowind hybrid power generating system, the hydropower station adjusts the generator to compensate. Wind energy is abundant not just in coastal or island places but also in rural and flat locations. The coastal, of course, is surrounded by water. If the rural is located near a river, it will be the best location for establishing a hydrowind hybrid power system (Peng et al., 2021).

Solar energy is a renewable energy source that is global, limitless, clean, and ecologically beneficial. However, the most significant disadvantage of solar energy is its volatility and intermittency, and the quality of solar electricity is heavily dependent on the season and weather. Wind energy, like solar energy, is a type of renewable energy source. However, when wind penetration grows, the quality of power supply is substantially jeopardized due to its features. Wind energy is difficult to anticipate due to its unpredictable and intermittent character, and the accuracy decreases with time, which may result in economic losses (Impram et al., 2020). Hydro-energy is a clean, easy-to-schedule renewable energy source, and using water for power generation is highly efficient, of low cost, and has a lower environmental effect. Hydropower is not only a significant role in the entire usage of water resources in many nations, but it is also one of the primary power generating sources. However, there are several limits in terms of available hydroenergy. For example, hydropower may be highly influenced by natural factors such as rain, and the cost of building hydropower facilities is considerable, making capacity expansion challenging. The ideal location, size, and plan of the hydroelectric power plant (HEPP) includes local topographies and geological conditions, the availability of water and head, the need for energy, the site's availability, and environmental issues as several variables that need to be considered. Adequate functional performance and safety are the most important elements of a HEPP construction. Hydropower is an energy created by turning the kinematic water energy into electrical energy. The renewable energy system is regarded to be the most frequently deployed kind. HEPP emits carbon dioxide and other greenhouse gases much lower than fossil fuels, and its total life cycle has a lesser environmental impact. Moreover, owing to the wide footprint of the biological effect of reservoirs and other required regions of the development, the environmental consequences of hydropower are likely to be larger than any type of energy generation (Şen, 2018). The discharge fluctuation, albeit a vast reservoir is provided to maintain a certain flow, is a basic disadvantage of hydropower. Temporary fluid flow variance can diverge in a lengthy yearly cycle by a factor of 5–10, which causes an intrinsic disruption of the grid's power supply. One way to mitigate this is to build consistent reservoirs, which may pump water into higher elevations with the use of surplus power when high water flows occur. This technology contributes to controlling the power generation but at the cost of significant power loss.

The tide generates forces that mostly come from the interconnected Earth–Moon system. The tidal power plants are described as dams built where the tidal range is enough to generate energy cheaply at turbines. The major parts of the main space power station are the embankments that constitute the impoundment's main artificial outlines, with a minimum length while increasing the surface area surrounded by the plane. A significant element in the design of the slope is the reduction of the natural tides flow disruption. In addition, turbines are positioned across the bench in the waterways and transform the potential energy generated by the head difference into rotating energy and then to power through generators (Neill et al., 2018). Tidal streams, like tidal elevation, are predictable; thus, combining the phasing of suitably large tidal stream arrays with tidal lagoons has the potential to improve the baseload production capacity from various facets of a single renewable resource. Because both the tidal range and the tidal streams display intermittency on spring/neap timeframes, they do not always provide peak generation at times of peak demand. Tidal energy phase optimization in conjunction with wind and wave energy, which naturally peak during the winter months, may help address this seasonal variability in demand; however, suitable predictive, coupled modeling techniques should be used to robustly assess the true generating potential and interactions between technologies and schemes (Widén et al., 2015; and Angeloudis et al., 2016). The problems faced by this sort of energy are environmental because flow change has biological and ecological effects: it will directly influence benthic habitats and on all species that spread through the free-floating of larvae. Changes in sediment transportation, mixing, and other physical processes may impact diving birds and pelagic predators/prey interactions. At the same time, the cost of electricity from marine power technology, the discounted project costs for life split by its energy output for life, is particularly sensitive to changes in the energy output and, therefore, the income that may be produced by interactions between the range of energy sources. This is because it combines high fixed costs with very low marginal generating costs (Waldman et al., 2019). Successful deployments and operations of turbines within those environments require better analyses of the implications of increased energy-extraction scenarios on the environment and the ecosystem and, in particular, the effects on marine quality. In fact, as the energy of tidal streams contributes to significant water transportation in estuarine and coastal marine systems, system-wide changes in hydrodynamic circulation and the transportation of water particles may be caused by operating turbine arrays. This involves trapping and dispersing changes of the dissolved nutrients and contaminants (e.g., petroleum, persistent poisons), organic particulate matter (e.g., plankton, gametes, larvae), and sediments. Large-scale effects are also predicted on biological processes, such as dissolved oxygen renovation or primary generation (Guillou et al., 2019).

Geothermal energy is heat derived from the earth's subsurface. It is found in the rocks and fluids underneath the earth's crust, all the way down to the earth's boiling molten rock, magma. To generate electricity from geothermal energy, wells are sunk a mile deep into underground reservoirs to obtain the steam and hot water, which is then utilized to drive turbines attached to electricity generators. Geothermal power facilities are classified into three types: dry steam, flash, and binary. The earliest kind of geothermal technology, dry steam, extracts steam from the earth and utilizes it to spin a turbine directly. Flash plants convert high-pressure hot water to cool, low-pressure water. In contrast, binary plants convert hot water to vapor by passing it through a secondary liquid having a lower boiling point. Less than 1% of total global energy demand is met by geothermal energy. It was noticed in 2015 that the global geothermal energy capacity climbed to 13.20 GW due to a significant addition of 315.0 MW. The geographic locations of geothermal energy farms, which supply about 72.01% of total global geothermal energy potential, are nearby Rim-Pacific hotspot features (Ahmad et al., 2020). An unstable rate of total geothermal energy installation capacity of roughly 43.01% is located in island nations or areas and suitable for applications such as heating, energy generation, and heat storage under ambient circumstances. The greater upfront cost of resource classification and exploration is a key barrier in proposing alternative geothermal locations. Recognizing the productive potential of such geothermal sources necessitates the use of quick models and low-cost technologies for evaluating and finding unmeasured geothermal energy resources (Tareen et al., 2018). The information provided on direct geothermal heat applications is based on nation updates submitted to the World Geothermal Congress 2020 (WGC2020). As stated at the end of 2019 for global geothermal direct use, the total installed capacity was 107.727 MW, an increase of 52.0% compared with the WGC 2015. The overall annual energy consumption is 1.020.887 TJ (283.580 GW h), an increase of 72.3% over the WGC 2015 and an annual growth compound of 11.5% (Lund and Toth, 2021).

Biomass is any organic substance originating from plants or animals that are alive or have been dead for a brief length of time. In plants, biomass is created when carbon dioxide in the atmosphere is converted into carbohydrates in the presence of sunlight. Biological species will subsequently proliferate by devouring these botanical or other biological species, contributing to the biomass cycle. Bioenergy obtained from biomass is a renewable source of energy that may be used to generate energy in place of nonrenewable sources such as coal. However, compared to coal, biomass, as given by nature, has a lower energy density, greater moisture, and more volatiles. As a result, biomass requires a pretreatment procedure to enhance its qualities before it can be utilized in conjunction with or as a replacement for coal (Mamvura and Danha, 2020). To count toward European Union (EU) objectives and be eligible for funding, biofuels and bioliquids must meet all sustainability requirements. The Renewable Energy Directive 2009/28/EC (RED) prohibits the use of many land types for biofuel production, including high biodiversity value land (primary forests, nature conservation areas, extremely biodiverse grassland), high carbon stock land (wetlands, wooded regions), and peatlands. The cross-compliance rules include the protection of soil and water quality, biological variety, the use of fertilizers/pesticides with caution, and air pollution. The influence of biofuels and bioliquids on biodiversity, water resources, water quality, and soil quality, as well as the reduction of GHG emissions, changes in commodity pricing, and land use linked with increased biomass usage, must be investigated. Fuel providers are expected to report on their compliance with the sustainability standards, as well as the actions they have done to preserve soil, water, and air; restore degraded land; and minimize excessive water usage in water-stressed regions (Scarlat et al., 2015). The expansion of direct renewables use in end-use sectors (buildings, industries, and transportation) would provide a 0.3%-point yearly renewables share increase, accounting for almost a fourth of the total. In 2050, biomass would account for two-thirds of direct renewable energy usage. Modern biomass heating applications and liquid biofuels are examples of this. Annual bioenergy supply would approximately quadruple from current levels to around 116 EJ in 2050 in terms of primary energy. This involves a transition away from old biomass uses and toward contemporary applications such as modern kitchen burners. Direct usage from the manufacture of liquid transportation fuels would account for around one-third, with the remainder coming from industrial uses, conversion into electricity, and district heating (Gielen et al., 2019).

Given the geographic variety required to build a reliable VRE-dependent power system, the location of VRE generators will not simply integrate with the infrastructure developed for earlier power production sources. Optimal VRE locations are frequently located distant from urban demand centers, necessitating the development of novel carbon-free ways of delivering this energy. Because of its capacity to carry huge amounts of energy over long distances with low losses, high-voltage direct current (HVDC) transmission lines are frequently regarded as perfect for energy transport (Semeraro, 2021). When the analytical method concentrates on particular current or prospective transmission projects, two major problems may result in overestimation of VRE transmission costs. First, because of the many goals and advantages of transmission, such as increased dependability and reduced congestion, defining the right financial responsibility for VRE transmission is challenging. The consequent underestimation of VRE transmission costs is exacerbated by VRE's comparatively low-capacity factors, resulting in reduced overall utilization of transmission projects completely assigned to VRE integration. Second, when you concentrate on VRE projects that need to be upgraded rather than on all VRE projects, some of them may not need to be retransmitted (Gorman et al., 2019). The considerable growth of environmental concerns has led to an increased usage of renewable energy technologies in the electricity grid. In particular, for the grid operators, significant technical problems arise from successfully integrating renewable energy technology into the electricity network: first, the placement of power plants and, second, energy intermittency and its major effect on the electricity system. The unpredictability of wind power generation demands the employment of voltage control devices with very fast reaction times. The usage compared to conventional control methods of Flexible AC Transmission System (FACTS) devices is thus suggested. In some substations, the shutdown of power plants produces excess voltage. The placement of inductors at their connecting points might prevent this problem. These are activated when solar output is shut down (Ameur et al., 2019). In comparison to gradual processes needed in developing and transforming existing power systems, renewable energy systems can be created on a big scale and connected to a grid over a relatively short period. There are several methods for increasing the flexibility of a power system, such as retrofitting existing coal-fired plants, constructing new pumped storage stations and gas-fired power plants, and using transregional power lines to provide energy supported in the neighboring power grids (Zhang et al., 2018).

When the sun shines, solar power is accessible, and wind power is accessible when the wind blows. Furthermore, their production projection is subject to weather forecasting inaccuracies. As a result, to ensure good supply security in power networks with a growing RES share, a rising quantity of backup and balancing power capacity is necessary. In the electrical system, demand and supply must be balanced at all times. The system operator ensures that the quality of power is maintained while minimizing production costs. In other words, power plants are dispatched depending on their marginal costs; hence, the most expensive power plants are only employed to meet peak demand (peaker capacity). As a result, in spot electricity markets, spot prices reflect supply shortages. In the long term, if there are no capacity payment mechanisms, a power plant must charge rates above its marginal cost to meet its fixed expenses (Karhinen and Huuki, 2019). The key to resolving the renewable energy power generation process when it is discontinuous and intermittent is how to store renewable energy when it is not needed and release renewable energy when required. Liu and Liang Du (2020) create a set of evaluation criteria for renewable energy storage systems based on four dimensions: technological, economic, environmental, and social, as illustrated in Fig. 1.6. Storage capacity is the amount of energy available in the storage system once it has been charged. The quantity of energy stored in a given space or mass is referred to as energy density, whereas power density is the ratio of battery output power to weight. Response time describes the pace with which energy storage technology absorbs and releases energy, whereas lifetime denotes the cycle life of charge and discharge energy. Emissions are the by-products of energy storage technology activities such as solid waste, wastewater, waste gas, etc. On the other hand, stress on the ecosystem indicates that the use of energy storage technology will consume a certain amount of land, vegetation, water resources, and so on and alter the original biological structure to some extent. As a result, it is critical to assess the friendliness of the ecological environment (Paster et al., 2011).

For a range of applications in the power industry, electricity storage technology may be employed, from e-mobility and behind-of-meter applications to utility applications. For instance, utility-scale batteries can allow increased feed-in renewables to the grid through the storage of surplus production and the strengthening of renewable energy. Batteries also assist in delivering dependable and cheaper electricity to distant power networks and remote settlements, which otherwise rely on expensive imported diesel fuel for generating electricity, particularly when combined with renewable generators. At the moment, utility-scale stationary batteries are the most common kind of energy storage in the world. On the other hand, small-scale battery storage is anticipated to grow considerably by 2030, complementing utility-scale uses. Behind-the-meter (BTM) batteries are installed behind the utility meter of commercial, industrial, or residential users with the primary goal of lowering power bills. BTM battery installations are on the rise all over the world. Because of the expanding consumer market and the development of electric vehicles (EVs) and plug-in hybrid EVs, the cost of battery storage technology has decreased (International Renewable Energy Agency, 2019).

The global energy transition is underway, propelled by the dual imperatives of minimizing climate change and promoting long-term prosperity. Some of the major facilitators of this trend include an extraordinary drop in renewable energy costs, new potential in energy efficiency, digitalization, smart technology, and electrification solutions. At the same time, the energy transition must occur considerably more quickly. To fulfill global climate goals, renewable energy deployment must rise at least sixfold beyond existing government projections. This would require accelerating the tremendous progress that we are now seeing in the electricity sector, as well as considerably increasing efforts to decarbonize transportation and heating. By 2050, electricity should grow to approximately 50% in overall energy use. Two-thirds of energy consumption and 86% of electrical output would then be made up of renewables. The biggest proportion of the energy sector reduction required may be renewable electrical energy coupled with deep electricity that could lower CO₂ emissions by 60%. Today's decisions worldwide will be important to secure a sustainable future for energy and climate. The Sustainable Development Goals and the Paris Agreement provide a framework through which the global energy transition activities may be coordinated and expedited.