Techno-economic and environmental analysis of an Aquifer Thermal Energy Storage (ATES) in Germany

The objective of the present study is to analyse the economic and environmental performance of ATES for a new building complex of the municipal hospital in Karlsruhe, Germany. The studied ATES has a cooling capacity of 3.0MW and a heating capacity of 1.8MW. To meet the heating and cooling demand of the studied building, an overall pumping rate of 963m(3)/h is required. A Monte Carlo Simulation provides a probability distribution of the capital costs of the ATES with a mean value of 1.3 +/-(0.1) million Euro. The underground part of the ATES system requires about 60% of the capital costs and therefore forms the major cost factor. In addition, the ATES is compared with the presently installed supply technology of the hospital, which consists of compression chillers for cooling and district heating. Despite the 50% higher capital costs of the ATES system, an average payback time of about 3years is achieved due to lower demand-related costs. The most efficient supply option is direct cooling by the ATES resulting in an electricity cost reduction of 80%. Compared to the reference system, the ATES achieves CO2 savings of about 600 tons per year, hence clearly demonstrating the potential economic and environmental benefits of ATES in Germany.