The potential for seabed geothermal energy in the UK

An international study has shown the potential for using capillary heat exchangers for heat pumps in the shallows of the seabed, with the potential to provide heating for homes.

A recent study jointly published by Nottingham Trent University, Zhengzhou University of Light Industry, Beijing University of Technology and Beijing Municipal Institute of Labor Protection showed that, with a seawater temperature of 3.7°C, capillary heat exchanger heat pumps could produce up to 60W/m² of thermal energy for residences located near the coast. 


The technology works by using a capillary heat exchanger – featuring capillary tubes with external  diameter of only 4.3mm - that extracts heat or cooling energy from the shallows of the seabed. 


Heat or cooling energy is then transferred to an indoor heat exchanger by pump. The indoor heat exchanger then heats or cools the indoor air of the property through a system similar to an air-conditioning unit. 


As part of the study, a hotel in Qingdao, China, was used to pilot test the technology. A 250-metre squaredcapillary was laid five metres deep in the shallows, 50 metres offshore. The total distance from the hotel to the capillary was 300 metres. 


The study will be available at the University of Nottingham’s Summer Conferences.