1. GROMIT project: GROund coupled heat pumps MITigation potential Anne Verhoef on behalf of the GROMIT team Department of Soil Science, University of Reading 1 GSHPA meeting, 21 January 2010, Milton Keynes NERC research grant

2. GROMIT team 2 GSHPA meeting, 21 January 2010, Milton Keynes  UoR/NCAS-Climate (land surface modelling & fieldwork): Raquel Garcia-Gonzalez, Bruce Main, Pier Luigi Vidale, Anne Verhoef  Nottingham University (modelling of GCHPs): Yupeng Wu & Guohui Gan  BGS (Groundwater modelling): Majdi Mansour & Andrew Hughes  CEH-Wallingford (UK 1 km driving data): Eleanor Blyth & Jon Finch  EarthEnergy Ltd (GCHP expertise): Robin Curtis Aim: To investigate and optimise the CO 2 mitigation potential of horizontal GCHPs under current and future UK environmental conditions

3. Infiltration Rates / Evaporation Energy balance/ground water level; vary in time and space) Water (vapour) flux, induced by heat extraction/rejection Thermal regime Thermal soil properties Soil water freezing/melting 3 GSHPA meeting, 21 January 2010, Milton Keynes GCHPs and environmental factors Primary source of energy, R n Top Boundary condition R n –(H+LE) = G Net Thermal Recharge Ground water Flow ~1.5 m Heat pump Horizontal GCHP Heat extraction / Cooling Lower Boundary condition F h =0 (T=constant) Diagram: Heat and water exchange processes near GCHP G, soil heat flux H, sensible heat flux E, evaporation Key variables: soil moisture content and soil temperature Largely affected by climate, soil texture & vegetation Courtesy of Raquel Garcia, Reading University

4. Type of horizontal GCHP Spacing of loops Installation depth Back-filling material Fluid in HE Pumps 4 GSHPA meeting, 21 January 2010, Milton Keynes GCHP-related technical & design factors Pump Compressor Evaporator Condenser Ground loop Load T1T1 T2T2 T2T2 T1T1 m m W T soil (W) Will affect COP, together with soil environment ! Courtesy of: Yupeng Wu, Nottingham University

5. 5 GSHPA meeting, 21 January 2010, Milton Keynes Project approach Model development (combined Land surface- Groundwater-GCHP model Experimental campaigns (UK field sites) Model simulation –Driving variables (UK 1 km grid) –Verification –Sensitivity - Varying model parameters –Climate change impact – COP under future environmental conditions –Climate change scenarios (UKCIP) Dissemination

6. Land surface model 6 GSHPA meeting, 21 January 2010, Milton Keynes

7. GCHP modelling 7 GSHPA meeting, 21 January 2010, Milton Keynes Plan view of isotherms generated from prediction for a slinkey heat exchanger, at 1, 10, 50 and 140 hours Courtesy of: Yupeng Wu, Nottingham University

8. UK driving variables 8 GSHPA meeting, 21 January 2010, Milton Keynes Rainfall Rate (kg m -2 d -1 ), 1 January 2003 Air Temperature (K) 1 January 2003 Courtesy of: Tongfei Zhang, CEH-Wallingford

9. UK soil textures 9 GSHPA meeting, 21 January 2010, Milton Keynes The National soil map, NATMAP (NSRI) Soil properties such as:  Dry bulk density  Hydraulic properties  Thermal properties Soil texture

10. 10 Field campaign started 2 th October 2009, near Oxford GCHP Profile over ~ 1m: - 8 Thermistors - 6 Thetaprobes slinky Cooling near the slinky due to heat extraction… how will this affect the water and heat transfer and hence the performance of GCHP…

11. GSHPA meeting, 21 January 2010, Milton Keynes 11 GCHP PROFILE REFERENCE PROFILE 4 trenches every 5 m 2 Profiles: -GSHP profile -Reference profile Soil temperature at 2 cm Soil temperature at 5 cm Soil temperature at ~1 m Soil moisture at 17.5 cm Soil moisture at 75 cm Soil moisture at ~1 m Courtesy of Raquel Garcia, Reading University

12. Conclusions 12 GSHPA meeting, 21 January 2010, Milton Keynes GROMIT is an excellent opportunity to address many unexplored issues related to horizontal GCHP performance in the UK Any questions/suggestions? Do you have a field-site available??? Thank you for listening!

13. UK driving variables 13 GSHPA meeting, 21 January 2010, Milton Keynes Surface temperature, 1 July 2003Surface temperature, 1 January 2003 Courtesy: Tongfei Zhang, CEH-Wallingford