state and federal policies investing in its employment, with its share in the primary energy rising to 10% by 2035, up from 3% in 2015. In addition, renewables account for 40% of the increase in power generation, making their share of global power rise from 7% in 2015 to approximately 20% by 2035 [3, 4].
RES is helped by nature and produce energy straight from the sun (thermal, photo‐chemical, and photo‐electric), indirectly from the sun (wind, hydropower, and biomass), or from other natural phenomena of the environment (geothermal and tidal energy). Renewable energy does not include energy resources originating from fossil fuels, waste products from fossil sources, or waste products from inorganic sources [5]. Renewable resources are gained from solar energy, wind, falling water, the heat of the earth (geothermal), plant materials (biomass), waves, ocean currents, temperature differences in the oceans and the energy of the tides. Renewable energy technologies turn these natural energy sources into practical forms of energy – usually electricity, heat, chemicals, or mechanical energy. Figure 2.1 illustrates an outline of renewables utilized across the globe and Figure 2.2 illustrates the theoretical potential of the RES which are able to provide over 3000 times the current energy consumption around the world [6]. In 24 hours, the sunlight that reaches the earth generates sufficient energy to meet the present energy requirements for 8 years [7–9].
The renewable energy markets – electricity, heating and transportation – have been rising over the previous five years. The integration of well‐known technologies, for example, hydro and additional advanced technologies including wind and solar photovoltaic, has increased rapidly, which gave confidence in the technologies, decreased prices and increased new opportunities [10]. Currently, renewable energy delivers approximately 18.3% of the final energy consumption, 50% of this percentage consists of advanced renewables, equally divided between electricity and direct heat applications, and the other 50% involves traditional biomass utilized for heating and cooking. The percentage of renewable energy in the total final energy will merely increase by 2030 from 18.3 to 21% [11]. Renewable energy generating capacity experienced its greatest annual rise ever in 2016, with approximately 161 Gigawatts (GW) of capacity added making the total global capacity almost 2017 GW, as illustrated in Figure 2.3. Furthermore, in 2019, renewables were responsible for approximately 7% of net additions to global power generating capacity [12].
Figure 2.1 Flowchart of the common renewable energy sources.
Figure 2.2 Renewable energy resources theoretical potential.
Figure 2.3 Total renewable power installed capacity (GW), including its annual growth rate, 2000–2019. Adapted from [12].
This chapter summarizes the benefits, growth, investment and deployment. Furthermore, challenges of integrating them into the electricity grid will be addressed. The content of this chapter is an updated and extension of earlier authors' publication [9].
2.2 Description of Renewable Energy Sources
2.2.1 Bioenergy Energy
Biomass includes all organic materials originating from plants and trees and entails the use and storage of the sun's energy by photosynthesis. Biomass energy (bioenergy) is the transformation of biomass into practical forms of energy including heat, electricity, and liquid fuels (biofuels). Biomass for bioenergy can originate from lands, for example, from dedicated energy crops and from residues produced in the processing of crops for food or different products [13–15].
Biomass energy is renewable and sustainable, but is comparable to fossil fuels. Even although biomass can be burned to acquire energy, it may additionally come as a feedstock to be transformed to numerous liquids or gas fuels (biofuels). Biofuels can be transported and stored, and permit heat and power production when needed, which is crucial in an energy mix with a high dependence on intermittent sources such as wind. These similarities are responsible for the essential contribution biomass is projected to offer in future energy usage [16]. Consequently, a plan to enhance biorefinery and biotransformation technologies to transform biomass feedstock into clean energy fuels is presently being developed. Interconversion of many biomass and energy forms in the carbon cycle is shown in Figure 2.4, [17]. Biomass feedstock can be transformed into bioenergy by thermo‐chemical and bio‐chemical transformation processes. These processes entail combustion, pyrolysis, gasification, and anaerobic digestion, as illustrated in Figure 2.5. Furthermore, the use of biomass‐derived fuels is to substantially counteract current energy security and trade balance problems, and adopt new socio‐economic improvements for many nations, as shown in Table 2.1 [18].
Biomass has the ability to reliably deliver baseload power, making it more favorable than other RES including wind and solar, however, the big disadvantage of biomass fuel is the lack of efficiency it possesses. Even although biomass could be utilized to generate energy to meet customer demand, biomass has huge amounts of water per unit of weight, which implies that it lacks energy potential as fossil fuels. Furthermore, transportation costs for biomass are greater per unit of energy than fossil fuels due to its small energy density.
The supply of biomass for energy has been growing at around 2.5% per year since 2010. The global Installed cumulative biopower capacity increased significantly from 39 GW in 2004 to 112.6 GW in 2016, Figure 2.6 shows the global biomass cumulative installed capacity from 2000 to 2013, [19]. Future projections suggest that biomass and waste energy production may rise from 62 GW in 2010 to 270 GW in 2030, as shown by Figure 2.7 [20].
Figure 2.4 Main features of the bioenergy energy technology. Adapted from [17].
Figure 2.5 Bioenergy conversion processes for different end products.
Table 2.1 Potential benefits and technical limitations of biomass energy. Adapted from Ref [18].
| Potential benefits | Technical limitations |
|---|---|
|
Environmental benefitsReduced
|
