A large supermarket or shopping center not only uses but also generates a huge amount of heat energy. The energy generated by cooling systems and the heat from the exhaust air together form a significant heat source.
Large markets have already made use of the condensation energy generated by cooling. For example, a large grocery chain implemented a solution in 2019 that efficiently recovers the condensation heat and exhaust air heat generated by the refrigeration systems in the store buildings. This recovered heat energy is recycled back into heating the stores. The solution will reduce the heat demand of commercial buildings by 85-95%.
This example shows that the potential for heat energy recycling is significant. However, for the time being, the benefits of energy recycling will primarily accrue to commercial buildings. In addition, the model whereby a shop sells its surplus heat to the district heating network is not efficient.
Feeding condensate heat into the district heating network requires a special heat pump with high investment costs. Another challenge is the price of heat sold to the network, which is being driven down by district heating companies. The heat energy collected from cooling and exhaust air should therefore be fed primarily into nearby buildings.
Markets have a surplus of heat
For much of the year, markets are in net surplus of heat. In particular, during the intermediate seasons, shopping centres and large markets have too much heat, while residential buildings have too little heating energy: the shops are already cooling while the residential buildings are still heating. In addition, residential buildings need hot water at all times, for example, which can be heated by the waste heat from shopping centres.
By connecting a commercial building to a geothermal local heating network, this surplus energy can be used more efficiently.In a district heating network, heating and cooling energy is recycled between surplus and deficit properties, while geothermal wells provide additional heating energy and store surplus heat. The thermal wells, which are around 2 000 metres deep, can also be used for cooling and energy storage. In addition, the heat network associated with the well allows the recovery of waste heat.
Geothermal energy reduces climate emissions from heating buildings by up to 95%. The only climate emissions from heat wells come from the electricity used by the heat pump. If the electrical energy used by the pump is 100% renewable, there are no emissions at all.
To be sufficiently effective in mitigating climate change, we need the courage to think differently about energy production. With the right initiative, in the near future large shopping centres and markets can be active producers of local heat and be the leading lights in neighbourhood-wide climate action.
Author: Rami Niemi Chief Technology Officer, Quantitative Heat
This opinion piece was published in Talouselämä's Tebatti column on 30 October 2022.
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