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Pietro Dalpane, Imperial College London |
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Salvador Acha, Ph.D., Imperial College London |
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Nilay Shah, Ph.D., Imperial College London |
Ground Source Heat Pumps (GSHP) provide with the opportunity to be coupled with refrigeration units. In principle, the heat rejected by refrigerators can be harnessed to raise the efficiency of the heat pumps.
This paper analyses the operational and economic performance of this innovative system deployed in Sainsbury’s supermarkets. First, the efficiency of the GSHP is evaluated, throughout the stores and over the period under consideration. Then, an economic analysis comparing the efficiency of investing in GSHP rather than in gas boiler systems is conducted. Recommendations on cost reductions are finally developed. Results show the Coefficient of Performance (COP) of GSHP systems to be highly dependent on the period of the year. During the summer, efficiency is roughly 40% less than during the winter. Overall, the efficiency of all the GSHP systems appear to be above the eligibility threshold for the Renewable Heat Incentive (RHI), with the average Seasonal COP (SCOP) of the stores being 3.0 in 2014. From an economic perspective, this average performance leads to roughly £120,000 of operational savings per year compared to gas boiler systems, with significant contribution stemming from the improvement in the refrigeration systems. Calculations show an investment payback time (PBT) of less than 8 years, a figure projected to rise slightly in the upcoming years as electricity becomes more expensive than gas.
Finally, this research project highlights cost reductions, achievable through two different approaches. First, by turning off heat pumps only when most economically convenient, up to 5.5% of the electricity costs can be saved among the stores and nearly 15% in stores boasting high thermal efficiency. Second, the profitability of the system deprived of the boreholes is evaluated. Despite the ineligibility for the RHI, the small CAPEX of this configuration could lower the PBT to 6 years.
This paper analyses the operational and economic performance of this innovative system deployed in Sainsbury’s supermarkets. First, the efficiency of the GSHP is evaluated, throughout the stores and over the period under consideration. Then, an economic analysis comparing the efficiency of investing in GSHP rather than in gas boiler systems is conducted. Recommendations on cost reductions are finally developed. Results show the Coefficient of Performance (COP) of GSHP systems to be highly dependent on the period of the year. During the summer, efficiency is roughly 40% less than during the winter. Overall, the efficiency of all the GSHP systems appear to be above the eligibility threshold for the Renewable Heat Incentive (RHI), with the average Seasonal COP (SCOP) of the stores being 3.0 in 2014. From an economic perspective, this average performance leads to roughly £120,000 of operational savings per year compared to gas boiler systems, with significant contribution stemming from the improvement in the refrigeration systems. Calculations show an investment payback time (PBT) of less than 8 years, a figure projected to rise slightly in the upcoming years as electricity becomes more expensive than gas.
Finally, this research project highlights cost reductions, achievable through two different approaches. First, by turning off heat pumps only when most economically convenient, up to 5.5% of the electricity costs can be saved among the stores and nearly 15% in stores boasting high thermal efficiency. Second, the profitability of the system deprived of the boreholes is evaluated. Despite the ineligibility for the RHI, the small CAPEX of this configuration could lower the PBT to 6 years.
See more of: Ground Coupled Heat Pumps