A field experiment has been carried out in the Lower Greensand near Cambridge to test the feasibility of injecting, storing and recovering heat in this formation. Approximately 1500 m3 of water at about 60°C were injected into the Lower Greensand over a period of 78 days. After storage for 105 days, the heat was abstracted over a period of 97 days. Over this single cycle of operation 33% of the injected energy was recovered. This proportion is likely to increase significantly with further injection/abstraction cycles. Increasing the amount of heat injected was also thought likely to reduce losses and increase the proportion of heat recovered.
A digital model of the Aquifer Thermal Energy Storage (ATES) system was set up and calibrated on the Cray IS system at the University of London Computer Centre. It was then used to predict the behaviour of larger ATES systems both on inter-seasonal and diurnal bases. Energy recovery factors of over 66% appear to be feasible.