What are the 4 solar technologies?

3.01.2.4.6 Reducing the risks of nuclear weapons proliferation

Competitive renewable resources could reduce incentives to build a large world infrastructure in support of nuclear energy, thus avoiding major increases in the production, transportation, and storage of plutonium and other radioactive materials that could be diverted to nuclear weapons production.

Solar systems, including solar thermoelectric and photovoltaics (PV), offer environmental advantages over electricity generation using conventional energy sources. The benefits arising from the installation and operation of solar energy systems are environmental and socioeconomical.

From an environmental point of view, the use of solar energy technologies has several positive implications which include [13]:

Reduction of the emission of the greenhouse gasses (mainly CO2, NOx) and of toxic gas emissions (SO2, particulates)

Reclamation of degraded land

Reduced requirement for transmission lines within the electricity grid

Improvement of the water resources quality.

The socioeconomic benefits of solar technologies include:

Increased regional/national energy independence

Creation of employment opportunities

Restructuring of energy markets due to penetration of a new technology and the growth of new production activities

Diversification, security, and stability of energy supply

Acceleration of electrification of rural communities in isolated areas

Saving foreign currency.

It is worth noting that no artificial project can completely avoid some impact to the environment. The negative environmental aspects of solar energy systems include:

Pollution stemming from production, installation, maintenance, and demolition of the systems

Noise during construction

Land displacement

Visual intrusion.

These adverse impacts present difficult but solvable technical challenges.

The amount of sunlight striking the earth’s atmosphere continuously is 1.75 × 105 TW. Considering a 60% transmittance through the atmospheric cloud cover, 1.05 × 105 TW reaches the earth’s surface continuously. If the irradiance on only 1% of the earth’s surface could be converted into electric energy with a 10% efficiency, it would provide a resource base of 105 TW, while the total global energy needs for 2050 are projected to be about 25–30 TW. The present state of solar energy technologies is such that single solar cell efficiencies have reached over 20% with concentrating PV at about 40% and solar thermal systems provide efficiencies of 40–60%.

Solar PV panels have come down in cost from about $30 W−1 to about $3 W−1 in the last three decades. At $3 W−1 panel cost, the overall system cost is around $6 W−1, which is still too high for the average consumer. However, there are many off-grid applications where solar PV is already cost-effective. With net metering and governmental incentives, such as feed-in laws and other policies, grid-connected applications such as building-integrated photovoltaics (BIPV) have become cost-effective. As a result, the worldwide growth in PV production is more than 30% per year (average) during the past 5 years.

Solar thermal power using concentrating solar collectors was the first solar technology that demonstrated its grid power potential. A total of 354 MWe solar thermal power plants have been operating continuously in California since 1985. Progress in solar thermal power stalled after that time because of poor policy and lack of R&D. However, the last 5 years have seen a resurgence of interest in this area, and a number of solar thermal power plants around the world are under construction. The cost of power from these plants (which is so far in the range of $0.12–$0.16 kWh−1) has the potential to go down to $0.05 kWh−1 with scale-up and creation of a mass market. An advantage of solar thermal power is that thermal energy can be stored efficiently and fuels such as natural gas or biogas may be used as back-up to ensure continuous operation.

In this volume, emphasis is given to solar thermal systems. Solar thermal systems are nonpolluting and offer significant protection to the environment. The reduction of greenhouse gasses is the main advantage of utilizing solar energy. Therefore, solar thermal systems should be employed whenever possible in order to achieve a sustainable future.

1 Introduction

The need for energy demands is constantly increasing globally, while stocks from conventional energy sources are finite. Locating and exploiting new sources of conventional energy is becoming increasingly difficult due to the unknown quantities of coal, oil, and gas reserves and their expensive and dangerous way of extraction [1].

In addition to the energy crisis, global warming, resulting in the potential threat of global climate change, is mainly due to Green House Gases (GHGs) mainly from CO2 emitted from fossil fuel consumption emissions, but also from other gases contributing to greenhouse effect. Climate change causes several negative effects on nature and humans [1,2].

Renewable Energy Sources (RES) produce energy from natural processes (e.g. sun, wind), which are replenished at a higher rate than consumed [3]. According to [4], renewable energy is the energy that is drawn from the repetitive energy flows, which constantly occur in the natural environment. Renewable energy technologies have significant potential for development, as these resources are globally distributed globally, contrary to conventional sources (gas, coal, oil), which are geographically concentrated. All countries have at least one abundant renewable resource, while the majority have a rich resource portfolio. The role of RES is expected to increase significantly over time in all scenarios of the International Energy Agency (IEA), with the largest contribution to electricity generation, heating and cooling and transport [3].

The most important benefits from the penetration of RES are: (1) Reduction of environmental impacts, including greenhouse gas emissions and other pollutants, (2) Energy security, (3) Economic growth strategy, and (4) Storage of energy distributed inside and outside the network.

The main forms of RES are the following [5]:

Solar energy is the energy produced by technologies using the sun radiation. Solar energy technologies are divided into: (1) photovoltaic solar systems, which directly convert the solar energy to electricity, (2) active solar systems, which convert the solar radiation in heat, and (3) bioclimatic design and passive solar systems, which include architectural solutions and the use of appropriate building materials to maximize the direct utilization of solar energy for heating, air conditioning, or lighting.

Wind energy is the kinetic energy, which is produced by the force of the wind and is converted into mechanical or electrical energy.

Geothermal energy is the thermal energy, which comes from the interior of the earth and is contained in natural vapors, in surface and underground hot waters, as well as in hot dry rocks.

Hydroelectric energy is the energy, which is produced from waterfalls for the purpose of generating electricity.

The European Commission has set up a fair transition mechanism to finance the green reform to a climate-neutral economy [6]. This mechanism consists of three main sources of funding: (1) A Just Transition Fund, which will be financed with new Community funds of €7.5 billion, in addition to the Commission’s proposal for the next long-term budget of the European Union, (2) a special regime of fair transition within the framework of InvestEU for the mobilization of investments and finding new sources of growth, and (3) a public sector lending mechanism in cooperation with the European Investment Bank.

It is obvious that according to the EU directions there is a need for energy transformation from fossil fuels to RES. Consequently, relevant policies have to be designed and energy RES projects need to be implemented. All these actions require the corporation of various actors on all policy levels.

One of the most important factors for the penetration of RES in the energy mix is their social acceptance. Public participation has been identified as a crucial factor to energy transformation from fossil fuels to RES [7]. In relation to the various forms of RES, the social acceptance of wind energy and the installation of wind farms are the two forms of RES that have been most investigated [8–11]. In addition, individual factors that influence the formation of social acceptance have been further examined, such as the level of knowledge of different forms of RES [8,12], the association of RES projects with NIMBY (Not In My Back Yard) syndrome [12], the impact of the information provided and the knowledge on the acceptance of RES [13], the attitude of citizens toward RES [8,12], as well as the willingness for additional payment for investments in RES technologies [8,13]. The role of economic, environmental and social impacts from the RES development on their social acceptance or rejection as well as the public perception of the benefits arising from the installation of RES projects has also been investigated [11]. An additional aspect that has also been considered is the ownership status of the bodies that implement and operate the RES projects, as well as the degree of the private sector involvement in the investment model of RES development [8].

Regarding Greece, some studies have focused on the issue of exploring the impact of demographic and socio-economic factors on the knowledge of different forms of RES [14], as well as the willingness for additional payment in order to promote the development of RES [15,16]. The social acceptance of specific forms of RES such as biomass has also been explored [17]. The most well-known forms of RES in Greece are solar and wind energy; biomass and biofuels are the least known forms and those that gains the least public support. The level of acceptance of different forms of RES differs between different regions depending on the past experience from RES projects installation. In areas where RES projects have been installed and are operating, in particular wind farms, a significant percentage of the residents are opposed to the installation; objections focus primarily on the visual disturbance and secondarily on the noise emitted by the operation of the wind turbines [18].

The present work investigates the social attitude toward RES by exploring their beliefs and perceptions, while highlighting the main parameters that affect their social acceptance. This works uses a structure questionnaire, as this type of research is effectively used to reveal the opinion of the citizens about environmental issues, such as climate change [19], energy use [20], water use [21], waste management [22], etc.

Abstract

The increase in global energy demand, coupled with the urgent necessity to transition to a fully sustainable energy infrastructure, means inexpensive, versatile and efficient solar energy technology will be in very high demand over the coming decades. Solar photovoltaic (PV) devices are reliant on highly specialized materials in order to harvest light as efficiently as possible. Many materials engineers are now using data science techniques to accelerate their search for new materials with optimized properties for solar devices. This chapter discusses such techniques, sorted into three overarching categories: machine learning for property prediction, high-throughput computational screening, and automated database generation.

We then focus in on case studies of recent projects that have used the above techniques to design novel materials for next-generation PV technologies which present an alternative to conventional silicon crystal cells: dye-sensitized solar cells, organic polymer PV and organic/inorganic hybrid perovskite PV devices. These devices share the benefit of using relatively cheap starting materials and they have unique applications, such as smart windows and wearable devices. However, each technology has also experienced limitations in material design which have acted as obstacles to commercialization. This chapter will discuss these issues and how the different techniques of data science for materials discovery are being used to overcome such bottlenecks. Following this, we look at a vision for the future of PV materials engineering in the form of “inverse design”, assisted by autoencoder machine learning methods.

1.06.4.2.4 Tax credits

At the federal level, most support for solar energy has come in the form of investment and PTCs. ITCs provide a partial tax write-off to those who invest in a particular solar energy technology. PTCs, by contrast, provide the investor or owner of a qualifying property with an annual tax credit based on the amount of electricity generated by the facility during the course of a year. In the United States, this credit has been available to eligible wind, hydro power, landfill gas, municipal solid waste, and biomass facilities [35, 55].

The ITC currently covers up to 30% of the cost of a commercial solar or wind project and 10% of the cost of a geothermal project. It has tended to favor commercial installations. From the start of the credit until 31 December 2008, the ITC in the United States capped residential investments in solar energy at $2000 but had no upper limit for commercial installations, creating an asymmetry that heavily favored centralized and large-scale projects [56].

One drawback is that many homeowners and manufacturers lack sufficient income to use the ITC efficiently, since they must have all of the capital up-front for investment and can only claim the credit when filing for taxes [57]. Perhaps because of these reasons, ITCs have played a supplemental, but by no means primary or driving role in investment in solar PV [58].

In 2008, the PTC reduced the price of renewable electricity by about 2 ¢ kWh−1 (the initial credit was 1.5 ¢ kWh−1, inflation adjusted) on a 20-year basis, in order to make investments in solar PV more attractive. To accomplish this incentive, however, the PTC also imposes a cost to US taxpayers in the form of displaced tax revenue. PTC disbursements amounted to about $4 million in 1995 but more than $210 million in 2004, and wind projects accounted for about 90% of all PTC-related tax credits [59]. A second shortcoming is that 90% of these expenditures were for one technology, wind, implying that the PTC does not promote diversification of the renewable resource base or investments in solar energy.

Tax credits

At the federal level, most support for solar energy has come in the form of investment and PTC. ITC provide a partial tax write-off to those who invest in a particular solar energy technology. PTC, by contrast, provides the investor or owner of a qualifying property with an annual tax credit based on the amount of electricity generated by the facility during the course of a year. In the United States, this credit has been available to eligible wind, hydropower, landfill gas, municipal solid waste, and biomass facilities. (Beck and Martinot, 2004b; Owens, 2004.)

The ITC currently covers up to 30% of the cost of a commercial solar or wind project and 10% of the cost of a geothermal project. It has tended to favor commercial installations. From the start of the credit until 31 December 2008, the ITC in the United States capped residential investments in solar energy at $2000 but had no upper limit for commercial installations, creating an asymmetry that heavily favored centralized and large-scale projects (National Solar Energy Laboratory, 2009). The cap was removed when the credit was reauthorized.

One drawback of using tax incentives to support solar is the need for tax equity. Many homeowners lack sufficient income and tax liability to actually use the ITC, since they must have all of the capital up-front for investment and can only claim the credit when filing for taxes (Bolinger, 2009). Further, tax exempt organizations, including nonprofits, Indian tribes, state governments, local governments, and religious organizations are unable to benefit from tax expenditures directly. In order for individual homeowners or tax exempt organizations to install solar PV under a tax incentive scheme they must find a third party tax equity partner. This increases costs as these partners charge premiums for using their tax equity, increasing the cost of energy. This financing structure has encouraged the proliferation of third party ownership and financing structures, particularly in California. Perhaps because of these reasons, ITCs have played a supplemental, but by no means primary or driving role in investment in solar (Lewis and Wiser, 2005). However, changing the structure of the tax incentive to a subsidy can increase deployment of solar PV. The 1603 Grant Program, part of the American Recovery and Reinvestment Act, allowed individuals to receive the ITC in the form of an upfront cash grant, removing many of the barriers of using tax incentives. This program has since solar and wind installations in the United States.

3.16.12 Conclusions

Among the energy sources suitable to drive desalination processes, solar energy is one of the most promising options due to the coupling of the dispersed nature and availability of solar radiation with water demand–supply requirements in many world locations [31].

The coupling of solar energy technologies with desalination processes is seen as having the potential to offer a sustainable route for increasing the supplies of potable water. The matching of solar energy with desalination does not have the capacity to solve the water crisis; however, it offers the potential of providing a sustainable source of potable water to some communities, particularly those in arid areas where there are no indigenous sources of fossil fuels. Keeping in mind the climate protection targets and strong environmental concerns, future water desalination around the world should be increasingly powered by solar and other natural resources. Such environmentally friendly systems should be potentially available at economic costs.

S4G Proposed Immediate Next Steps

S4G seeks to design and enact, in partnership with engineers, students, educational institutions, and other organizations, renewable energy training sessions and a renewable energy technical capability study in Gaza.

Renewable energy training sessions, lasting 2–3 days, would focus on technical skills development and would aim to exchange and disseminate practical and applicable knowledge for building solar energy technologies. The training session would also build a network among engineers, students, and community leaders. The training session could be carried out in Gaza or in another country such as Egypt, Jordan, or Israel, depending on feasibility and receptiveness, and be led by local and international experts on renewable energy.

A territory-wide renewable energy self-sufficiency potentials study should explore the physical, economic, social, and political capacity for locally managed renewable energy infrastructures in Gaza as a basis for local and regional development, income generation, and reconciliation, delivering rapid implementation scenarios. An international team partnering with Gaza's expert communities should carry out such a study. In fact, S4G has already outlined and proposed such a study in detail.

Educational opportunities for young Gazans seeking further training or advanced degrees in solar engineering should be provided, in order for them to be well equipped for the future rebuilding process of their communities.

An S4G fund is to be established to source and provide investment streams supporting essential and comprehensive solar infrastructures in Gaza and beyond.

S4G calls for Israel and the Palestinian territories with their respective international partners to pursue a “Peace for Climate Accord” initiative—as the world’s first official recognition of the need to cease hostilities and blockades to be able to join forces in combating climate change—an infinitely greater threat than anything emanating from within the region.

14.8 Cost-Effective Perovskite Solar Cell

Celik et al. designed a more cost-effective and large-scale processable perovskite solar cell using SnO2 and CuSCN as ETL and HTL, respectively [50]. The device architecture is FTO/SnO2/CH3NH3PbI3/CuSCN/MoOx/Al. FTO was preferred over ITO as it is cheaper than ITO, and indium is designated as “critical metal” by the US Department of Energy’s Solar Energy Technologies Program. There are four commonly used ETLs. They are TiO2, ZnO, Al2O3, and SnO2. Among these, TiO2 is the most commonly used ETL, but its high-temperature processing is not suitable for manufacturing flexible solar cells on a large scale and it consumes more energy. Similar is the case with ZnO and Al2O3. These are not compatible for low-cost production. On the other hand, SnO2 which has energy band match with perovskite is low temperature processable. Spiro-MeOTAD is the most commonly used organic HTL. But it is very expensive and unstable. Other organic HTLs are P3HT, PTAA, etc., and again the cost of these materials is very high. CuSCN is a copper-based inorganic HTL with better stability, high hole mobility, and ease of processability. Al with MoOx interface forms a less expensive back contact compared to Au and Ag back electrodes. As discussed in Section 14.2.2, there are several methods to coat the perovskite layer such as spin coating, sequential deposition, spraying, printing, and co-evaporation technique. Among these, spray and inkjet coating would be a better option for large area coating. In this study, Celik et al. has used CH3NH3PbI3 as the active material. HTL-free perovskite solar cells have gained popularity due to its low cost and stability. An LCA study of HTL-free perovskite is also studied using carbon paste back contact.

A cradle-to-grave LCA study was conducted for the same structure assuming an active area of 65%. Using the TRACI impact assessment model, impact categories like human toxicity, cancer and noncancer, acidification, GWP, ecotoxicity, primary energy demand, and eutrophication were modeled. Celik et al. have compared the environmental impacts of perovskite solar cell with the first- and second-generation solar cells. It is clear from Fig. 14.9 that the acidification impacts are high for solution-processed and HTL-free perovskite solar cells. But the overall impact of perovskite solar cells is lower than the mono-Si solar cells. The environmental impacts of perovskite solar cells are high when compared to the existing commercial technologies. The electricity required for manufacturing perovskite solar cell is high when compared to other solar cells in market. The only way to reduce the environmental impacts is to improve the PCE and lifetime of perovskite solar cells.