The Chesire Basin is one of several deep sedimentary basins that comprise permeable Permo-Triassic formations containing groundwater that is heated by conductive heat flow. Given sufficient temperatures, these systems can be used to provide direct heat or used in conjunction with heat pumps or combined heat and power systems (as at Southampton in the Wessex Basin).
In general terms groundwater within basin systems needs to be tapped at depths of 1 – 1.5 km or 2 – 3&nbdp;km to produce water temperatures in excess of 40°C and 60°C respectively. Geothermal reservoirs offer a finite resource but typically have life spans of decades and can be re-commissioned after a rest period. Longevity of the reservoir can be maximised by re-injection of the spent geothermal fluid, which is typically returned to the aquifer at temperatures of around 30°C. This type of system is referred to as a doublet.
The Cheshire Basin contains vast thicknesses of Triassic and Permian sediments that have characteristics of depth, thickness and transmissivity that make them suitable targets for geothermal exploration. This research indicated that temperatures encountered at depths of up to 4.5 km within the Cheshire Basin are unlikely to exceed 100°C and are therefore unsuitable for efficient electricity generation given existing technology. However an excellent thermal resource exists in both the Triassic and Permian aquifers that is equivalent to the energy content of 1833 million barrels of oil, and could provide a source of low carbon heat for the Crewe area.