Bill Rodger (Trinity CC) looks at the DHN role in local energy strategy:
Background
Still rare in the UK, District Heating Networks (DHN) are common in Europe. Well over a century old, the technology has seen several generations of improvement. DHNs move heat around using warm water rather than fuel and generally share a common heat source. That may be waste heat, a large boiler or an industrial scale heat pump. The greenness of their output is largely determined by the greenness of the heat source but because upgrading the heat source immediately upgrades potentially hundreds of individual homes DHN offers future proofing while technological change advances.
Modern materials have hugely improved DHN efficiency (5% heat loss over 40 km is claimed). This means that a diverse portfolio of heat sources can be incorporated and continually upgraded.
Inside the house, making the switch to DHN generally means replacing your (almost certainly gas) boiler with a (slightly smaller) heat exchanger. Your radiators continue to function.
Looking forward
Scottish Government requires all 32 LA’s to produce a Local Heat and Energy Efficiency Strategy (LHEES). Edinburgh’s will shortly go to consultation. In setting out the framework for LHEES Scottish Government listed 3 broad technology groups - Energy Efficiency, Heat Pumps and DHN.
Scotland already has some DHNs but they are small scale. Aberdeen Heat & Power operates 5 small networks mostly introduced to combat fuel poverty. Edinburgh has around 150 sites where individual buildings share a common boiler but only a single network connecting several Edinburgh University buildings. However there are well advanced plans for DHN at Granton Waterfront and Shawfair.
Scotland’s targets imply a sevenfold increase over the next 7 years. In cities, where potential is greatest, this will be much higher. Early indications from Edinburgh's LHEES suggest that DHNs have the potential to cover over 50% of Edinburgh's population. Commercial arrangements will need to be struck for investment in the areas with greatest potential and the ongoing provision of the service. Scottish Futures Trust is backing DHN.
Experience from Scandinavia highlights that network benefits increase exponentially with scale implying a discussion about investment in infrastructure to hasten DHN take-up and keep individual connection costs low. Private investment will need to be leveraged. Government regulation is needed to avoid market abuse and to harmonise technical standards so that the full advantages of an integrated network can be achieved.
The future for heating the UK’s homes will not remain as it is now with a single dominant fuel. For the individual householder, DHN should be seen as one of several tools to reach Net Zero. It will therefore be important for Edinburgh’s residents to be aware of the likelihood and timescales for DHN to be introduced into their area so that they can take an informed decision when it comes to replacing their boiler.
Nor should DHN be seen in isolation. Rather it needs considered in conjunction with other measures – as should heat pumps. Improving the insulation in your home will also be advisable and brings immediate benefits in lower fuel bills.
Role for Community Councils and EACC
EACC will continue working with other organisations to keep CCs informed and, through them, individual families. DHN implies some disruption including roadworks. It will help if people understand what the purpose of the disruption is.
So far as we can we will seek to influence CEC and SG to ensure that options are maximised for the people of Edinburgh and that people are aware of the timelines for their area.
Important to both the above will be good two-way engagement with the LHEES output. That should be seen as a dialogue not as an inflexible plan.
27 Oct 2023
End / BR