Ground source heat pumps are well suited to district heating applications and there are many good examples of their use in countries across the world.
Before we get into the pros and cons of these systems, I think a quick explanation of what they are is in order.
What is a district heating system?
District heating systems are simply systems that are powered by a central heat source instead of by multiple individual heat sources for each house, office or other building.
The system relies on well-insulated pipework to convey the heat generated by the central boiler/heat pump to all the buildings on the network.
There is usually a heating main that transports hot water from the heat source to the other buildings on the network. At each of the buildings served by the system, the heat from the heating main is transferred to that building’s heating system via a heat exchanger.
Having given up its heat to the building via the heat exchanger, the (now cooler) water in the heating main is pumped back to the boiler and the heating cycle is repeated.
Benefits of a District Heating System
Most of the benefits of a district heating system stem from the principle of economies of scale. Some of the main benefits are as follows.
- Cheaper cost of installation. It is typically cheaper to install a single larger boiler than to install multiple smaller units. There is less pipework and fewer things to go wrong.
- Cheaper to service and maintain. Servicing costs can be kept lower due to the fact that a service engineer only has one location to visit and a single unit to work on.
- Fuel costs can be less. Operating a larger boiler means that it is possible to buy fuel in bulk. In the case of ground source heat pumps, the costs of pumping from a single borehole or trench are lower than from multiple ones.
- Lower climate impact. For many of the same reasons fuel and servicing costs are cheaper, you can reduce your carbon footprint. There will be fewer miles travelled when service engineers only visit a single site, for example.
Where Can a District Heating System be Installed?
The answer to this is pretty much anywhere there are groups of houses, offices or other buildings that require heating. Provided the heat source(s) can be installed nearby and the individual buildings requiring heating are close enough together, a district system is possible.
If ground conditions are favourable, then a ground source heat pump district heating system can be a very attractive option.
There are some great examples of district heating and cooling in Helsinki and Wandsworth that you can read about published by the Department for Energy and Climate Change.
Also, building on research conducted in Wales on the use of minewater in the South Wales Coalfield as a source of heat, there has been a specific study carried out by the Scottish Government into the Potential for Deep Geothermal Energy in Scotland.
This is an area ripe for further research and I expect to see much more of this in future.