Summary of seasonal thermal energy storage field test projects in the United States

Abstract

Seasonal thermal energy storage (STES) involves storage of available heat or chill for distribution at a later time to meet thermal loads. STES can reduce energy consumption, peak energy demand, and emissions of carbon dioxide to the atmosphere over conventional systems. It is estimated that full-scale application of STES would provide 2% to 4% of total energy needs in the United States. One STES technology, aquifer thermal energy storage (ATES), has been determined to be the most cost-effective option in the United States when site conditions enable its use. ATES has been analyzed in the laboratory and investigated in the field in the United States since the program was established at Pacific Northwest Laboratory (PNL) in 1979. Two field test facilities (FTFs), one for heating ATES at the University of Minnesota and the other for cooling ATES at the University of Alabama, have been primary testing grounds for US ATES research. Computer models have been developed to analyze the complex thermal and fluid dynamics. Extensive monitoring of FTFs has provided verification of and refinements to the computer models. The areas of geochemistry and microbiology have been explored as they apply to the aquifer environment. In general, the two FTFs have been successful in demonstrating the steps needed to make an ATES system operational.