Assessment of the resource base for engineered geothermal systems in Great Britain

Jon Busby,Ricky Terrington

doi:10.1186/s40517-017-0066-z

Abstract

An assessment of the engineered geothermal system (EGS) resource base that might be available for the generation of electricity for Great Britain has been undertaken by adopting a globally self-consistent protocol that if universally adopted, would allow estimates of EGS made for different countries and regions to be comparable. Maximum estimated temperatures at depths of 5 and 7 km are greater than 200 and 300 °C respectively, a considerable increase over previous estimates. The total heat in place in the basement, to a depth of 9.5 km that is theoretically available for EGS is 357,197 EJ. If it were possible to develop just 2% of this resource, this would be equivalent to 1242 times the final UK energy consumption in 2015. The theoretical and technical potential power has been calculated from the available heat in place. The total technical potential power, to a depth of 6.5 km, is 222,393 MWe and represents just 0.4% of the theoretical potential power. Current EGS exploitation is more likely to be restricted to a depths of around 4.5 km and reservoir temperatures greater than 175 °C. In which case technical potential power is mainly restricted to regions of high heat producing granites and represents a total technical potential power of 2280 MWe. However, improvements in drilling technology are expected to enable economic drilling to depths of 7 km or greater that will enable EGS exploitation in all regions of Great Britain.

Highlights

Engineered or enhanced geothermal systems (EGS) have been promoted as a technology that exploits geothermal heat and power production from regions of the crust devoid of shallow high enthalpy reservoirs (e.g., MIT 2006)
This paper presents an evaluation of the prospective resource base for EGS power generation in Great Britain (GB) by applying the protocol of Beardsmore et al (2010, 2011), hereafter referred to as the protocol
Heat in place estimates have been made for direct use geothermal in Great Britain based on the deep Mesozoic basins and range from 198–293 × 106 TJ (Busby 2014), indicating that the geothermal resource base for EGS is around 700 times that for direct use

Summary

Background

Engineered or enhanced geothermal systems (EGS) have been promoted as a technology that exploits geothermal heat and power production from regions of the crust devoid of shallow high enthalpy reservoirs ( referred to as high-grade hydrothermal resources) (e.g., MIT 2006). Rollin (2002) lists heat generation for the principal British geological formations, the mean of which for sedimentary rocks (AS; to base Devonian) was 1.17 μ Wm−3 and this single value was adopted across the sediment thickness grid. Since surface heat flow is a critical parameter in the estimation of EGS potential, a crude regional correction scheme for palaeoclimate has been applied It is based on published palaeoclimate and topographic heat flow corrections at six borehole sites across Great Britain (Westaway and Younger 2013), over the East Grampians batholith in eastern Scotland (Busby et al 2015) and over the southwestern England granites (Beamish and Busby 2016).

Discussion

Findings

E England

Conclusions