Making Solar Heat Add Up: Potential for Solar Thermal in Europe

The European Union and its Member States have committed themselves to achieving a 20% share of renewable energy in Europe’s final energy consumption by 2020. As only three renewable sources (biomass, geothermal and solar) generate heat, it is crucial to clarify how these different sectors can contribute to the renewable energy target. A new study being released this autumn – Study of the Potential of Solar Thermal in Europe, which has come from two Austrian bodies (AEE – Institute for Sustainable Technologies and Vienna University of Technology) examines the growth that can come from solar.

solar thermalObviously, solar thermal systems will be needed to provide a substantial share of the low temperature heat: deep geothermal sources are limited to a few locations in Europe, and shallow geothermal is considered within this study as an energy efficiency technology; biomass will be used for transport fuels, electricity generation and medium-to-high temperature applications.

In order to provide the European Union and its Member States with substantiated information on the solar thermal contribution to the 20% renewable energy target and its long-term potential, detailed surveys were conducted using a representative sample of five European countries – Austria, Denmark Germany, Poland and Spain. The information gathered was then extrapolated to cover the 27 EU countries. The study examined both the technical and economic potential of solar thermal technologies, for different applications, including low-temperature industrial heat requirements and cooling.

In order to determine the potential contribution solar thermal could make to the overall heat demand in the selected reference countries, a model was developed for the future demand – taking into account energy efficiency measures. Using this model as a base, future heating and cooling demand was calculated for 2020, for 2030 and 2050. The model includes three scenarios and focuses on the following segments:

  • space heating of residential buildings
  • hot water preparation in the residential sector
  • space heating in the service sector
  • industrial low temperature heat (up to 250°C)
  • air conditioning and cooling in the residential and service sectors

The three scenarios are a ‘Business As Usual scenario’ (BAU); an ‘Advanced Market Deployment scenario’ (AMD), which includes financial and political support mechanisms such as subsidies and obligations, moderate energy efficiency measures and improved research activities; and a ‘Full R&D and Policy scenario’ (RDP), which includes substantial financial and political support mechanisms, energy efficiency measures and research activities.

Contribution of Solar Thermal to the EU 20% Renewable Energy target

Assuming there is a 9% reduction of the overall final energy demand due to energy efficiency measures by 2020 (compared with 2006), then solar thermal would make up 6.3% of the European Union’s 20% renewable energy target under the RDP scenario, and 2.4% under the less ambitious AMD scenario. The share of renewables in 2005 (to the EU-27’s total energy consumption of 13,609 TWh) was 8.5%. To reach 20%, an increase of 11.5 percentage points in renewable energies is required across the EU-27 countries by 2020. The contribution of solar thermal to that increase would be 12% according to the RDP scenario, 4.5% according to the AMD scenario and 2.9% in the BAU scenario.

Combi systemsTo reach the goals of the RDP scenario, a 26% average annual growth rate of the European solar thermal market is needed up to 2020. (By comparison, the average annual market growth in Europe between 2000 and 2007 was 12.4%.) A 15% average annual growth rate is required to reach the goals of the AMD scenario and a 7% growth rate for the BAU scenario. The resulting total collector area by 2020 would be between 97 million m2 (BAU) and 388 million m2 (RDP). These collector areas correspond to total installed capacities of 67.9 GWth and 271.6 GWth, respectively.

Economic Effects

According to the RDP scenario the effect on employment would be considerable. In total, the solar thermal sector would encompass 470,000 full-time jobs in 2020, in the European Union domestic market alone. €214 billion would be required in the solar thermal sector to reach the 2020 goals of the RDP scenario. This includes production, engineering, trade and installation of solar thermal systems from 2006 to 2020.

Solar thermal contribution to the energy supply and CO2 reduction

The solar yield in the RDP scenario is 155 TWh in 2020. This corresponds to an oil equivalent of 22 billion metric tons. Taking this oil equivalent into account the annual contribution to the CO2 reduction by solar thermal systems is 69 million metric tons.

Technology Innovation

Stepping up solar on this scale will require innovation. In order to use the potential much larger roof and facade areas will be needed for the installation of solar collectors.

Large-scale solar renovation of buildings will make use of prefabricated elements, with solar providing space heating, cooling and hot water. Combisystems will play an essential part, and a key issue is the development of thermal energy storage.

Long-Term Potential – Beyond Domestic Hot Water

In 2050, the solar thermal contribution to the European Union’s (EU-27) low temperature heat demand ranges from 47% (RDP scenario) to 8% (BAU scenario). The corresponding annual solar yields are 1552 TWh (RDP) and 391 TWh (BAU). The collector area needed to reach these goals is between 8 m2 (RDP) and 2 m2 (BAU) per inhabitant in the EU-27. The resulting total collector area is between 3.88 billion m2 (RDP) and 970 million m2 (BAU).

If solar thermal is to contribute significantly to the long-term heating and cooling demand in EU-27 countries then the primary focus in central and northern Europe must be on systems for space heating (solar combisystems) and in the Mediterranean area on systems providing space heating, hot water and air conditioning (solar combi+ systems).

Figure 1









If the focus remains solely on solar thermal systems for domestic hot water preparation, then the solar thermal contribution to the long-term final energy demand will be limited. By 2030 the full potential for these applications will have been reached and the market would be reduced mainly to the replacement of old systems. Another important segment with considerable potential is low-temperature process heat for industry, (up to 250°C).

With upscaled R&D and market/political support, solar heat can make a valuable contribution to Europe’s energy future. It’s the right moment – in fact, without the renewable heat sector, the 2020 targets will not be reached.

Werner Weiss is at AEE – Institute for Sustainable Technologies, Gleisdorf, Austria. Peter Biermayr is with Vienna University of Technology Energy Economics Group, Austria. 

The full version of the Solar Thermal Potential in Europe study is available at here.

This study was prepared in the framework of the EU-funded project RESTMAC, TREN/05/FP6EN/S07.58365/020185. The Solar Thermal partner in the RESTMAC project is ESTIF, European Solar Thermal Industry Federation.

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