Thermal modelling of large scale exploitation of ground source energy in urban aquifers as a resource management tool

• Electrical heat pumps for building heating and cooling is key for low carbon cities.
• Modern buildings have unbalanced energy demands leading to heat plumes in the aquifer.
• The impact of current ground source energy in London is modelled at the aquifer scale.
• Currently approved schemes are sustainable, but there is evidence of interference.
• Achieving Ground Source Energy targets will need regulation for sustainability.

As part of its legal commitment to reducing CO2 emissions, the UK has outlined a roadmap for significant increases in the use of ground source heat pumps for heating and cooling buildings. The technology is particularly suitable in new buildings, and in large commercial buildings. Such development is focussed in urban areas of economic growth. This paper presents an aquifer scale model of the impact of the expansion of open loop ground source energy schemes deployed in London. The model predicts the impact for currently operating schemes, and also the potential impact of all open loop schemes that have been licensed in central London. It is concluded that there will be thermal interference between these schemes and that in areas with such a high density of ground source energy schemes, the resulting loss of efficiency will mark an effective limit to the energy available for unbalanced ground source cooling. The current unregulated approach to managing the energy resource of the Chalk aquifer beneath London will not be able to sustain the demands implied by the UK roadmap for ground source energy. A more actively managed approach is needed if these energy demands are to be met, economically, in London and other centres of economic growth.