Prospects for solar cooling - An economic and environmental assessment

Producing refrigeration and/or air conditioning from solar energy remains an inviting prospect, given that a typical building's cooling load peaks within 2 or 3. h of the time of maximum solar irradiation. The attractiveness of "free" cooling obtained from the sun has spawned a wealth of research over the last several decades, as summarized in a number of review articles. Obstacles-especially high initial costs-remain to the widespread commercialization of solar cooling technologies. It is not clear at the present time if thermally driven systems will prove to be more competitive than electrically driven systems. We therefore describe a technical and economic comparison of existing solar cooling approaches, including both thermally and electrically driven. We compare the initial costs of each technology, including projections about future costs of solar electric and solar thermal systems. Additionally we include estimates of the environmental impacts of the key components in each solar cooling system presented. One measure of particular importance for social acceptance of solar cooling technologies is the required "footprint," or collector area, necessary for a given cooling capacity. We conclude with recommendations for future research and development to stimulate broader acceptance of solar cooling. The projections made show that solar electric cooling will require the lowest capital investment in 2030 due to the high COPs of vapor compression refrigeration and strong cost reduction targets for PV technology.