Comparison of five approaches to solar assisted cooling
Paper in proceedings, 2009
Numerous different options are available for cooling buildings using solar energy. In this theoretical study, which is also a pre study for a pilot installation, five generic technologies are compared: 1. Conventional compressor chiller fed by electricity from PV panels 2. Absorption chiller fed by a combination of medium temperature solar heat and district heating 3. Absorption chiller fed by a combination of low to medium temperature solar heat and district heating 4. Evaporative cooling (tower) fed by electricity from PV panels 5. Desiccant cooling fed by medium temperature solar heat and district heating The financial viability of each technology will essentially depend on competing supply energy tariffs, local climate, time distribution of cooling loads, the internal cooling distribution system, subsidy levels and expected operational costs. Furthermore, the buyers' choice of a system will also be affected by the fact that the technologies are in different stages of maturity. From the point of view of the district heating provider potential impact on the heating network is also of great interest. The study compares the five technologies in the light of these different aspects. The paper describes the method in more detail as well as the results of the study. The best overall conditions were found for a combination of PV powered conventional chillers which, according to calculations have a significantly lower LCC than the reference district cooling, even if subsidies are not taken into account. The concept based on free cooling from a wet cooling tower powered by PV has a much lower cost than the chiller, but the technical feasibility of this new and very energy efficient technology is not yet considered to be proven. Results from the economical analysis of solar assisted district heating powered comfort cooling varies within a wide range depending on the tariff applied for the district heat.