Solar systems integrated with absorption heat pumps and thermal energy storages: state of art

Renewable energy sources (including hydropower, wind, biomass, geothermal, tidal, wave and solar energy sources) can satisfy the present and future energy demands, with minor environmental impact respect to traditional sources of energy. Solar energy is the cheapest and widely available renewable energy and solar cooling systems are a green cold production technology that produce minor CO2 emissions due to use of heat pumps. Infect, absorption refrigeration is a mature technology that has proved its applicability with the possibility to be driven by low grade solar energy. In this contest, thermal storage systems contribute to balance the disadvantages of the intermittent nature of solar energy and the variation in cooling demand, receiving more attention of researchers in the recent years. This paper presents an innovative and comprehensive literature review on solar systems integrated with environmental-friendly processes as absorption heat pumps and thermal energy storages. A study about processes regarding the renewable and sustainable energy according the European policy is carried out. Photovoltaic and photovoltaic/thermal solar systems can be used to this purpose and are the most promising technologies growing very fast in recent years. Researches show that one, half, two effect of absorption heat pumps integrated with solar systems and thermal energy storages can be an attractive alternative in cooling systems, meeting the demands for energy conservation and environmental protection. Showing various systems, a discussion about the improvement of cooling applications respecting the environment is also presented in this paper.