Direct Solar Energy
Table 3.6 | Overview of parameters for sensitivity (Graf et al., 2008).
Heliostat costs (USD2005
Redox system costs (USD2005/kg)
Electricity costs (USD2005/kWhe)
Electrolyzer (decrease in %)
Chemical application (decrease in %)
Recycling of nitrogen (decrease in %)
Optimistic 114 30 17 0.05
Forecasts for the future deployment of direct solar energy may be underestimated, because direct solar energy covers a wide range of tech- nologies and applications, not all of which are adequately captured in the energy scenarios literature. Nonetheless, this section presents near- term (2020) and long-term (2030 to 2050) forecasts for solar energy deployment. It then comments on the prospects and barriers to solar energy deployment in the longer-term scenarios, and the role of the deployment of solar energy in reaching different GHG concentration stabilization levels. This discussion is based on energy-market forecasts and carbon and energy scenarios published in recent literature.
In 2010, the main market drivers are the various national support pro- grams for solar-powered electricity systems or low-temperature solar heat installations. These programs either support the installation of the systems or the generated electricity.The market support for the different solar technologies varies significantly between the technologies, and also varies regionally for the same technology. This leads to very dif- ferent thresholds and barriers for becoming competitive with existing technologies. Regardless, the future deployment of solar technologies depends strongly on public support to develop markets, which can then drive down costs due to learning. It is important to remember that learn- ing-related cost reductions depend, in part at least, on actual production and deployment volumes, not just on the passage of time, though other factors such as R&D also act to drive costs down (see Section 10.5).
Table 3.7 presents the results of a selection of scenarios for the growth in solar deployment capacities in the near term, until 2020. It should be highlighted that passive solar gains are not included in these sta- tistics, because this technology reduces demand and is therefore not part of the supply chain considered in energy statistics. The same PV technology can be applied for stand-alone, mini-grid, or hybrid systems in remote areas without grid connection, as well as for distributed and
12 Complementary perspectives on potential deployment based on a comprehensive assessment of numerous model-based scenarios of the energy system are presented in Sections 10.2 and 10.3.
centralized grid-connected systems. The deployment of CSP technology is limited by regional availability of good-quality direct-normal irradi- ance of 2,000 kWh/m2 (7,200 MJ/m2) or more in the Earth’s sunbelt. As shown in Table 3.7, solar capacity is expected to expand even in refer- ence or baseline scenarios, but that growth is anticipated to accelerate dramatically in alternative scenarios that seek a more dramatic trans- formation of the global energy sector towards lower carbon emissions.
Photovoltaic market projections at the end of 2009 for the short term until 2013 indicate a steady increase, with annual growth rates ranging between 10 and more than 50% (UBS, 2009; EPIA, 2010; Fawer and Magyar, 2010). Several countries are discussing and proposing ambi- tious targets for the accelerated deployment of solar technologies. If fully implemented, the following policies could drive global markets in the period up to 2020:
The National Development and Reform Commission (NDRC) expects non-fossil energy to supply 15% of China’s total energy demand by 2020. Specifically for installed solar capacity, the NDRC’s 2007 ‘Medium and Long-Term Development Plan for Renewable Energy in China’ set a target of 1,800 MW by 2020. However, these goals have been discussed as being too low, and the possibility of reach- ing 20 GW or more seems more likely.
The 2009 European Directive on the Promotion of Renewable Energy set a target of 20% RE in 2020 (The European Parliament and the Council of the European Union, 2010), and the Strategic Energy Technology plan is calling for electricity from PV in Europe of up to 12% in 2020 (European Commission, 2007).
The 2009 Indian Solar Plan (‘India Solar Mission’) calls for a goal of 20 GW of solar power in 2022: 12 GW are to come specifically from ground-mounted PV and CSP plants; 3 GW from rooftop PV systems; another 3 GW from off-grid PV arrays in villages; and 2 GW from other PV projects, such as on telecommunications tow- ers (Ministry of New and Renewable Energy, 2009).
Relating to US cumulative installed capacity by 2030, the USDOE- sponsored Solar Vision Study (US DOE, 2011) is exploring the following two scenarios: a 10% solar target of 180 GW PV (120 GW central, 60 GW distributed); and a 20% solar target of 300 GW PV (200 GW central, 100 GW distributed).
Long-term deployment in the context of carbon mitigation
The IPCC Fourth Assessment Report estimated the available (tech- nical) solar energy resource as 1,600 EJ/yr for PV and 50 EJ/yr for CSP; however, this estimate was given as very uncertain, with sources reporting values orders of magnitude higher (Sims et al., 2007). On the other hand, the projected deployment of direct solar in the IPCC Fourth Assessment Report gives an economic potential contribution of