HEAT NETWORKS | CP3 CODE OF PRACTICE Figure 1: Extraction and reinjection of groundwater in an open-loop GWSHP Local geology and borehole yield need early consideration. If the geology isnt right, you could be looking down the wrong well for almost free passive cooling offer extremely high CoPs. A better measure of these systems is the seasonal performance factor (SPF), including all the energy used and supplied, in particular the borehole pump. This is covered in detail by CP3. Although boreholes can be expensive to drill, they represent a long-term asset way beyond the life of the heat pump itself. With the decarbonisation of the electricity grid and high SPFs, carbon savings are considerable. A number of studies (some through the BEIS Heat Networks Delivery Unit) show that large-scale heat pumps easily beat CHP on carbon savings. CHP is still generally winning on economics, however, mainly because of the low cost of gas in the UK. GWSHPs show good viability, but CHP produces high-value electricity, resulting in a client dilemma: do I go for the highest cost savings or the highest carbon savings? Given the urgency of the climate problem, the route should be long-term carbon, not short-term operational cost. However, the added potential for load shifting to run heat pumps when electricity is either lower cost or lower carbon, or both, could offer opportunities to financially outscore CHP, even at todays raw utility pricing. The Renewable Heat Incentive (RHI) is a huge support, but why do heat pumps need this sort of subsidy? Its simply because gas is too cheap (being effectively subsidised) and this reduces the value of low carbon heat compared to electricity the UK spark gap is one of the biggest in Europe. If gas was double the price, as in some other countries, subsidy support may not be needed. The RHI has picked up the financial gap, but is closing in April 2021. Referee! Can we have a level playing field please? Will a follow-on scheme take its place? Work continues on this but, in parallel, changes to Building Regulations and to planning law will encourage low carbon heat in preference to low carbon electricity in the built environment. Pitfalls to avoid Local geology and borehole yield need early consideration. Wells may be ~120m deep to reach the groundwater; if the geology isnt right, however, you could be looking down the wrong well. This needs specialist input from those who understand the detailed geology. Its about the science, and GSHPAS GRIDWATCH The Ground Source Heat Pump Association (GSHPA) has information, case studies and standards on heat pumps. Its website also includes a live carbon calculator GridWatch comparing CO2 emissions from different technologies. Membership is open to large and small organisations, including consultants and individuals. Visit www.gshp.org.uk risk management and mitigation CP3 says more on this. Another significant factor is locating boreholes too close together, which can result in thermal breakthrough (essentially recirculation in the aquifer). CP3 discusses well spacing. Again, this is highly dependent on the local geology, so it is important to obtain advice from a specialist hydrogeologist and to consult the EA about any potential issues. The well heads can be as simple as an unobtrusive manhole cover in the street, so location can be less of an issue than people think, although drilling rig access can be a challenge. A very early conversation with the EA is essential, long before a full application for an abstraction licence. The EA will check for obvious issues, such as others already abstracting in the same area. CP3 also addresses the temperature change between abstraction and injection, because this figure is likely to be an EA stipulation. Essentially, if you follow CP3, the EA application should go smoothly but start early. A code of practice to decarbonise heat If GWSHPs are to form a significant part of our future low carbon energy infrastructure, they need to be designed, built, operated and maintained to the highest level, to deliver customer satisfaction. CP3has been produced to help achieve these aims by raising standardsacross the supply chain, thereby encouraging adoption. Setting minimum requirements for a project and recommending best practice will provide greater confidence to specifiers and developers. CP3 can be included in the tendering/contracting process to specify these. In turn, the adoption of this code of practice by developers will give assurance to customers and property purchasers that their GWSHP scheme has followed a set of design, installation and commissioning standards. So CP3 should have a significant effect on the GWSHP market by boosting confidence across the board. Replacing or extending the RHI is essential if the heat-pump sector is going to compete with current gas pricing but, more fundamentally, weve got to stop burning stuff, and move to a more renewable-based energy system. Using heat in groundwater will play a key part in this, and CP3 offers everything you need to get this technology right. May the code be with you. Go on open the loop. CJ PHIL JONES is an independent energy consultant and chair of CP3 Steering Committee, and a GSHPA Council member BEAN BEANLAND is chair of the GSHPA BEIS awarded CIBSE a grant for CP3 from public funds 36 August 2019 www.cibsejournal.com CIBSE Aug19 pp35-36 CP3 Code.indd 36 26/07/2019 15:08