Monday, September 2, 2019

United Kingdom: Geothermal Energy Experts Weigh in on Decarbonization

A long, hard look underground is required to reach net zero, say experts (Heriot-Watt University)

Advances and investment in geothermal energy, carbon capture and storage (CCS) and bioenergy with carbon capture and storage (BECCS) are “critical” to moving the UK towards its target, according to a new report published in Petroleum Geoscience.

Roy Baria, Technical Director of EGS Energy, discussed the importance of hot dry rock and the advances that engineered geothermal systems will provide without the need for naturally convective hydrothermal resources. Until recently, geothermal power systems have exploited only resources where naturally occurring heat, water and rock permeability are sufficient to allow energy extraction. However, EGS technologies enhance geothermal resources in hot dry rock through hydraulic stimulation.

Also looking for high enthalpy heat was Thomas Driesner (ETH Zurich), who described the potential of ‘superhot’ geothermal in Iceland at a depth of 2 km immediately above a magma body, producing superheated steam reaching 450°C and 140 bar at the wellhead. At the Larderello Field in Tuscany, described by Adele Manzella of CNR Italy, two European projects are also looking at deep chemical–physical conditions in an area characterized by very high heat flow in one of the most productive hydrothermal systems in the world.

Charlotte Adams of Durham University described a geothermal opportunity in relation to the legacy remaining from over two centuries of intensive coal mining, which has left a flooded underground asset that is estimated to contain some 2.2 million GWh of available geothermal heat from two billion cubic metres of water at temperatures which are constantly around 12–16°C. Using heat pumps and exchangers, these temperatures can be increased to 40–50°C and the mine waters kept away from the surface. Adams pointed out that over one-quarter of UK homes overlie worked coalfields and could access this source of geothermal energy and seasonal heat storage.

Geoscience and decarbonization: current status and future directions
Michael H. Stephenson, Philip Ringrose, Sebastian Geiger, Michael Bridden and David Schofield. Petroleum Geoscience, 29 August 2019,