INTEGRATED REGULATION OF (GEO)THERMAL SUBSURFACE USE(S) AND GROUNDWATER

Hydrogeology and groundwater regulation have always played an important role in geothermal energy, specifically in the exploration and development of high enthalpy (deep) geothermal resources. More recently, hydrogeological involvement and regulations have expanded to include the development of ground-coupled heat-pump based systems that provide space heating and/or cooling.

In the UK, groundwater regulations are the main mechanism to control the operation of such systems. Currently, regulations only apply to systems which make direct use of groundwater as heat exchanger medium (open-loop systems) via abstracting / re-injecting groundwater as part of the heating/ cooling process, whereas systems which extract heat indirectly (closed-loop systems) by circulating a heat exchanger fluid through pipe loops installed in the subsurface remain largely unregulated. However, these systems can have considerable impact on heat availability and temperature distributions within the subsurface, specifically where groundwater flow is present, and thus regulatory mechanisms need to be put in place that provide better controls on the use of subsurface thermal resources via these systems.

This presentation demonstrates potential impacts of high-density closed loop installations on groundwater temperatures and on the availability of thermal resources. It looks at current regulatory approaches for heat abstraction in the subsurface, in the presence/ absence of groundwater resources, and presents arguments and solutions for integrated regulatory approaches that can manage the increasing use of subsurface heat and groundwater resources by ensuring resource sustainability on the one hand without compromising stakeholder / investor confidence on the other hand.