ShareCombining thermal energy storage and heat pumps
A borehole thermal energy storage (TES) system, used in conjunction with heat pumps is designed to heat and cool buildings at the north campus of the University of Ontario (UOIT) in Oshawa, Ontario, Canada.
A borehole thermal energy storage (TES) system, used in conjunction with heat pumps is designed to heat and cool buildings at the north campus of the University of Ontario (UOIT) in Oshawa, Ontario, Canada.
The system has been operating since 2004 and integrates heat pumps which operate alternatively in heating or cooling mode and the borehole TES which also includes ground-based heat pumps.
The total cooling load of the campus building is about 7000 kW. The 7000-m² and 1.4 million-m3 borehole TES field is divided into four quadrants in order to optimize seasonal energy storage, it comprises 384 boreholes, each 213-m deep, through which a glycol solution circulates within 150 km of polyethylene tubing.
Central ground-source heat pumps are a key to the system. Two chillers, both equipped with seven 320 kW-modules, transfer energy from the buildings to the borehole TES and two sets of heat pumps, each equipped with seven 180 kW-modules, assist in cooling.
The field then retains the condensing heat for use in the winter when the heat pumps reverse and provide low temperature hot water (53°C) for the campus. Almost all services use this low-temperature hydronic heat.
Thanks to the TES system, annual energy use is reduced by 40% for heating and 16% for cooling. The payback period for the geothermal field was 7.5 years when the system was designed and 4 years for the high-efficiency HVAC equipment incorporated since.
IEA Heat Pump Newsletter, Volume 31 - No. 1/2013
The system has been operating since 2004 and integrates heat pumps which operate alternatively in heating or cooling mode and the borehole TES which also includes ground-based heat pumps.
The total cooling load of the campus building is about 7000 kW. The 7000-m² and 1.4 million-m3 borehole TES field is divided into four quadrants in order to optimize seasonal energy storage, it comprises 384 boreholes, each 213-m deep, through which a glycol solution circulates within 150 km of polyethylene tubing.
Central ground-source heat pumps are a key to the system. Two chillers, both equipped with seven 320 kW-modules, transfer energy from the buildings to the borehole TES and two sets of heat pumps, each equipped with seven 180 kW-modules, assist in cooling.
The field then retains the condensing heat for use in the winter when the heat pumps reverse and provide low temperature hot water (53°C) for the campus. Almost all services use this low-temperature hydronic heat.
Thanks to the TES system, annual energy use is reduced by 40% for heating and 16% for cooling. The payback period for the geothermal field was 7.5 years when the system was designed and 4 years for the high-efficiency HVAC equipment incorporated since.
IEA Heat Pump Newsletter, Volume 31 - No. 1/2013