Title: Assessment of a full-scale, multi-year, aquifer thermal energy storage demonstration project

Authors: K. Clerk Midkiff, C. Everett Brett

Addresses: College of Engineering, The University of Alabama, 290 Hardaway Hall, Tuscaloosa, AL 35487-0276, USA. ' College of Engineering, The University of Alabama, 290 Hardaway Hall, Tuscaloosa, AL 35487-0276, USA

Abstract: A 520 kW (peak, thermal) Aquifer Thermal Energy Storage (ATES) based air-conditioning system has been operated and monitored since 1983. The system is used to cool a 5800 m² student recreation building on the University of Alabama campus in Tuscaloosa (USA). During cold weather, ambient ground water is chilled using either a cooling tower or a spray pond, and is reinjected into a water table aquifer for storage. After storage for periods of up to several months, chilled ground water is recovered for building cooling during warm weather. Measurements of water chilling, thermal energy storage and cooling performance are presented for eight years of operation. The fraction of the chill energy stored that is recovered for building cooling has ranged from 40 to 85 percent. An annual average of about 4.8 units of cooling per unit of electricity input has been measured, a value about twice that of conventional air-conditioning equipment installed at the same time. From a gross efficiency standpoint the energy performance of the system has been quite good. However, the quality of the air conditioning has suffered in late summer as chilled water temperatures become too warm to provide adequate dehumidification. Recent modifications to the system, including the addition of a large chilling capacity spray pond and additional wells, have been aimed at reducing this problem. In addition to the technical aspects of this demonstration project, economic and environmental advantages of ATES systems and obstacles that impede their more extensive use are identified. In particular, problems that have arisen with the design and implementation of the ATES system in this project are discussed. Appropriate applications of the technology, both in industrialized and in developing countries, are identified.

Keywords: aquifer thermal energy storage; full-scale multi-year ATES; aquifers; air conditioning; building cooling.

DOI: 10.1504/IJGEI.1997.063335

International Journal of Global Energy Issues, 1997 Vol.9 No.3, pp.199-211

Published online: 10 Jul 2014 *

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