
The International Energy Agency has called for greater political support for increasing the amount of solar thermal power after the launch of a report which found that solar thermal technology could meet one-sixth of the planet’s demand for heating and cooling, saving 800 megatonnes of carbon dioxide emissions a year by 2050.
The report outlined a roadmap for development and deployment of solar heating and cooling by 2050 to produce 16.5 exajoules of solar heating annually and 1.5 exajoules of solar cooling.
“Awareness is growing of the urgent need to turn political statements and analytical work into concrete action,” said IEA executive director Maria van der Hoeven. “To spark this movement, at the request of the G8, the International Energy Agency (IEA) is leading the development of a series of roadmaps for some of the most important technologies.
“The global energy need for heat is significant in both OECD and non-OECD countries: in 2009 the IEA reported that global energy demand for heat represented 47% of final energy use. Solar heat thus can make a substantial contribution in meeting climate change and security objectives.”

Satellite-derived solar resource map
As solar radiation passes through the earth’s atmosphere, some of it is absorbed or scattered by air molecules, water vapour, aerosols, and clouds. The solar radiation that passes through directly to the earth’s surface is called direct solar radiation. The radiation that has been scattered out of the direct beam is called diffuse solar radiation. The direct component of sunlight and the diffuse component of skylight falling together on a horizontal surface make up global solar radiation.
The key findings of the report are detailed below:
- Solar collectors for hot water and space heating could reach an installed capacity of nearly 3 500 GWth, satisfying annually around 8.9 EJ of energy demand for hot water and space heating in the building sector by 2050. Solar hot water and space heating accounts for 14% of space and water heating energy use by that time.
- Solar collectors for low-temperature process heat in industry (<120°C) could reach an installed capacity of 3 200 GWth, producing around 7.2 EJ solar heat per year by 2050. Solar process heat accounts for 20% of energy use for low temperature industrial heat by that time.
- Solar heat for cooling could reach a contribution of 1.5 EJ per year from an installed capacity of more than 1 000 GWth for cooling, accounting for nearly 17% of energy use for cooling in 2050.
- Swimming pool heating could reach an installed capacity of 200 GWth, producing annually around 400 PJ solar heat by 2050.
- By achieving the above mentioned deployment levels, solar heating and cooling can avoid some 800 megatonnes (Mt) of CO2emissions per year by 2050.
- Achieving this roadmap’s vision requires a rapid expansion of solar hot water heating in the building sector, including in solar supported district heating, as well as in industrial applications. Dedicated policy support should overcome barriers related to information failures, split incentives and high up-front investments.
- While a number of industrial and agricultural processes can use low-temperature flat-plate collectors, advanced flat-plate collectors and concentrating technology should be further developed to produce medium-temperature heat. Industrial process heat offers enormous potential in sectors that use low- and medium-temperature heat for processes such as washing, leaching (mining industry), drying of agricultural products, pre-heating of boiler feed water, pasteurisation and cooking.
- The development of compact storage will allow heat to be used when the load is required, aiding the deployment of solar space heating in individual buildings. Dedicated research, development and demonstration (RD&D) resources could make compact storage commercially viable between 2020 and 2030.
- Solar cooling could avoid the need for additional electricity transmission capacity caused by higher average peak loads from the rapidly increasing cooling demand in many parts of the world. It can also allow for a more optimal use of solar energy applications for domestic hot water, space heating and cooling. With substantially higher RD&D resources, standardised, cost competitive and reliable solar cooling systems could enter the market between 2015 and 2020.
The IEA also outlined key actions they believed were necessary for governments to action:
- Create a stable, long-term policy framework for solar heating and cooling; establish medium-term targets to maximise the effective use of mature and nearly mature technologies, and long-term targets for advanced technologies that have yet to reach the market.
- Introduce differentiated economic incentives on the basis of competitiveness per technology by means of transparent and predictable frameworks to bridge competitive gaps. Incentives could for example be based on feedin tariffs or renewable portfolio standards for commercial heat and subsidies or tax incentives for end-user technologies. Economic incentive schemes should be independent of state budgetprocedures to avoid “stop-and-go” policies where, for example, sudden withdrawal of incentives can destabilise the market.
- Address barriers such as information failures, up-front investment of technologies, lack of quality standards and the ‘split-incentive’ problem (where the investor in SHC technology does not reap the benefits of reduced energy costs). This can be done through awareness raising campaigns, industry training and education, support for new business models and modified regulations.
- Provide RD&D funding and support mechanisms to enable promising pre-commercial solar heating and cooling technologies to reach high volume commercial production within the next 10 years.
- In developing countries, expand the efforts of multilateral and bilateral aid organisations to accelerate the deployment of mature and competitive solar heating and cooling technologies, addressing both economic and non-economic barriers.
Source: IEA (PDF)
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