Solar Energy Perspectives - IEA

Solar Energy Perspectives: Solar heat
Thermal storage for daily or weekly applications is generally affordable. Storage for longer
periods of time is more challenging. The possibilities appear to be either inexpensive sensible
heat storage media or high energy density systems. To limit volume (other than using the soil),
developers of space heating systems put their hopes in the development of efficient and
affordable thermo-chemical storage systems (see Chapter 4). Because most CSP plants are
located in semi-desert areas, and thanks to their high working temperatures, seasonal thermal
storage could perhaps be achieved with inexpensive media, such as stones (see Chapter 8).
Thermal storage finally includes various means to store cold, not only heat. A simple but
efficient example is making ice from thermally driven cooling devices. Melting of the ice will
deliver cold when needed.
Costs of solar heat
The actual costs of solar heat are more difficult to define than for other applications of solar
energy, as they depend not only on the resource – which is free – and the technology – which
is not – but also from the effective use of the heat collected, which can be significantly
variable. Figure 7.11 shows estimates of solar heat costs for solar supported heating networks
and low-temperature industrial process applications, today and in 2030, under two different
resource regimes in Europe. Chapter 4 gives information on costs for solar water heaters.
Figure 7.11 Price of solar thermal generated heat versus conventional energy sources,
for solar supported heating networks .
and low temperature industrial process applications > 350kW th
17.5
15.0
Heat cost, EUR cent per kWh
Electricity
150 000 MWh/a
1 100 000
Natural gas
Source: Weiss, 2011.
Key point
Low temperature solar heat will become more broadly competitive for district heating services and industry.
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© OECD/IEA, 2011