Guardbridge geothermal technology demonstrator project: feasibility report

8. Network Design

Based on the estimated heat production rates of the target geothermal resource, a heat pump-based system would not be able to provide enough heat for any of the proposed network options outside of the Guardbridge Energy Centre itself. It was therefore decided that the final network design should be focused on supplying heat to the future developments around the Guardbridge site as these are situated close to the proposed well locations and would require the least length of pipe to be connected.

Figure 8.1: Final network design overlain on proposed Guardbridge Energy Centre development plan (the former paper mill site).

The buildings shown in colour in Figure 8.1 are the ones scheduled to be completed in the first development phase and so have been targeted for the first connections. To ensure that the network will remain flexible and able to supply further developments around the site, several capped points have been proposed that will enable other buildings to connect in the future; these are shown in black end points in the plan (Fig. 8.1). It is noted that the network design will require updates based on the timing of building development on the Guardbridge site.

8.1 Well location

This smaller more localised network also benefits from the fact that the preferred well option for the project was proposed to lie inside the Guardbridge site, hence eliminating the need for any long stretches of transmission pipe to get from the well-head to the geothermal energy centre or heat demand.

The geothermal energy centre and production well have been placed a short distance apart to allow for future maintenance of the borehole. Initially it is estimated to require a drilling area of approximately 65 x 65 m, while any subsequent work would require just 45 x 45 m. This smaller maintenance allowance can be seen in Figure 8.1 as the blue hashed square around the production well and the initial drilling footprint is the black square around this. Due to the footprint required for drilling such a deep borehole, all construction around the site would have to wait until after the well had been completed. However, this is the most likeky case as the well production would have to be proved valuable before construction of the geothermal energy centre took place.