Planning for Renewable Energy in Worcestershire Research Paper

Ground/Water/Air Source HeatPumpsGround source heat pumps (GSHP)extract the heat energy storedunderground and use it to contribute toheating water, either through directlycirculating water underground, or throughcirculating an intermediary fluid. A suitablearea of land adjacent to the building isrequired in which the pipework can beburied. This can be done eitherhorizontally (in which case a large landarea will be needed), or vertically in adeep bore (depth of 15m-150m), whichcan be more expensive. One of theprincipal benefits of the systems is thatthey do not require any externalconditions (e.g. strong direct sunlight) inorder to work efficiently. Due to thenear-constant temperature of the earth(c.10-12oC) at a depth of around 2m, thesystem can be used all year round,although it is unlikely to produce sufficientoutput to be the sole source of heat,especially during the winter. Typical costsfor a horizontal system are £800 - £900per kW; for a vertical system, costs maybe in the region of £1000 - £1500 per kWAs a technology that requires excavations(either vertical or horizontal), there existsa risk with GSHP that archaeologicalremains could be disturbed or destroyedduring installation/maintenance. Theinstallation of GSHP is being included ashouseholder permitted development,meaning that planning permission wouldnot be needed, which could consequentlyreduce the likelihood of proposals beingreferred to archaeological officers foradvice. It is therefore suggested thathouseholders choosing to install a GSHPsystem take reasonable care that therewill be no adverse archaeological impactsarising from the installation. If in anydoubt, consultation with professionaladvisors is recommended.Water-source heat pumps employ asimilar principle to ground-source, butextract the heat energy from a body ofwater instead of from the ground. Thismethod is unlikely to deliver significantreturns County-wide, as it depends on asuitable body of water (such as a lake)being in close proximity to the buildingusing the heat. Water-source systems arealso less efficient during winter months(susceptible to freezing, etc).Air-source heat pumps extract heatenergy from the air outside a building andtransfer it to be used as space heatinginside. The air temperature in the WestMidlands is probably insufficient toprovide any major heating gains, but thesystem also allows cool air to becirculated inside a building, which canprovide a more sustainable alternative toair-conditioning.Ground, water and air-source heat pumpsall rely on a small input of energy topower the pumping mechanism. The'coefficient of performance' determinesthe relationship between the energyrequired to be input, and the energy gainsfrom the system. For ground source, thisequates to a ratio of approximately 3-4units of heat energy received for everysingle unit of energy to run the system.Air-source pumps are less efficient.GeothermalGeothermal heat is extracted from theearth to provide direct heat energy, in theform of hot springs, etc. However, it isunlikely that this will be a suitable methodof energy generation in the County, as thetemperatures below the earth are too low.According to the Halcrow study, "…thegeological structure of the region is suchthat temperatures are not sufficientlyelevated near to the surface to allow theuse of geothermal heat".APPENDIX A ● Planning for Renewable Energy in WorcestershireTechnical Research Paper 41