How it Works
The Future for District Heat Networks
Established Technology
District heat networks are widely used around the world. Denmark, as an example, is one of the most advanced countries in terms of district heat use.
The widespread use of district heat is one of the primary reasons that Denmark’s energy efficiency has increased and carbon emissions have decreased over the past several decades. Denmark has six large, central district heat networks located around major cities and urban areas in addition to 400 smaller decentralised district heating networks. Today, around 64% of all Danish households are connected to district heat networks for heating and hot water and a number of these networks use air source heat pumps which are powered by renewable electricity. In Copenhagen approximately 80% of buildings are connected to district heating.
Air Source Heat Pumps work in the same way as a refrigerator, which extracts heat from inside the refrigerator and transfers it out into the environment. An Air Source Heat Pump extracts latent heat from the air before transferring this heat into water. This process works at temperatures well below 0oc.
The Air Source Heat Pumps will be located at an energy centre. The heated water will then be circulated via a network of underground pipes connected to buildings. The heating systems of buildings can be connected to this network so that it can be used as the primary source of heating instead of gas boilers. Like any energy system, there will be occasions when an energy back-up is required.
Currently, the most cost-effective back-up option is for the BEN to use gas boilers. On the coldest days, gas boilers would be used to top up the heat provided by the source heat pumps. Gas boilers would also be used as a back-up in case of a grid outage which would mean that the air source heat pumps weren’t able to function. This system minimises the use of gas boilers while ensuring certainty of energy supply. Over time new sources of heat will be added to the network which would lead to less use of the back-up gas boilers.
The gas boilers are expected to initially supply 10-15% of total heat demand for the heat network with 85-90% coming from the air source heat pumps. To achieve zero carbon, BEN will use renewable energy from the grid and offset the carbon for any gas used.
How the Bradford Energy Network will work
The district heat network being brought forward in Bradford will be the largest scale Air Source Heat Pump district heating network in the UK.
Its development and delivery will be funded partly through the Green Heat Network Fund (GHNF), a source of grant funding from the Department for Business, Energy and Industrial Strategy (BEIS), and partly through private investment from 1Energy.
District heat networks provide heat on a large scale and can provide properties that are separated by several miles with heat from the same source. In its first phase the district heating network will provide a low-to-zero-carbon heating solution for key buildings in Bradford city centre. There is, however, the ambition and potential to expand the network significantly over the near term to areas adjacent to the city centre.
