It is possible to use electricity generated from wind, solar PV or hydro systems to heat water for district heating. This would involve the use of a central electric boiler or heat pump (powered by the renewable generator) which acts as the heat source for a heat network.
Why would you want to consider this? Renewable electricity generators often produce more electricity than can be exported to the grid and, depending on their location, may be routinely ‘switched off’ to avoid overloading the network. If your asset is constrained in this way you could keep it switched on for longer (and maximise your income) by bypassing the grid and using the electricity locally to generate heat. Bearing in mind that renewable energy is inherently variable, the value of such a system would be further enhanced by incorporating an element of thermal storage so that hot water can be stored when the excess electricity is available.
Owen Square Community Energy’s ‘Choices’ Project is an example of a renewable energy powered district heat system.
Another option might be to install an electric (private wire) network which would distribute electricity directly to multiple connected buildings and could be used to power electric boilers, electric storage heaters or direct electric heating systems in individual households. An electric network may be a more suitable option than a district heat network if the following criteria apply:
- You have available excess renewable electricity due to limited grid capacity
- You are in an area where energy generation is close to the point of heat demand
- Your excess electricity generation is more or less adequate to meet the heat demand with or without thermal storage
- You are in an area with high cost of existing heat sources (likely to be off the gas grid)
The feasibility of a hydro to heat system was tested by Applecross Community Company Limited in 2014. The study looked at heat provision options for a district heat system (using either a central heat pump or electric boiler) and an electric private wire connection to individual buildings.