Decarbonising the City Centre

It’s great to see that the City Council is doing a feasibility study of how to decarbonise the city centre using a district heating network.

The idea is that this would take heat from a variety of low carbon sources and supply it to buildings which would be hard to decarbonise otherwise.  Examples of some of the initial users include the Guildhall, Corn Exchange, Parkside Swimming Pool, and the Lensfield road Chemistry Labs. Heat sources could include ground source heat pumps (for example from boreholes under Parkers Piece, Midsummer Common and Jesus Green), air source heat pumps (for example on the roof of the Engineering Department), thermal stores with top-up electric boilers and waste heat from data centres, or even heat from the River Cam.

4 shortlisted clusters identified in Feasibility Study

Ecologists point out that cooling the river slightly would actually help reduce the risk of fish die-off events in summer, because cooler water can hold more oxygen.

Carbon Neutral Cambridge first became aware of this idea a year or so ago, and we encouraged the City Council to be bold and to work with University to explore it.

Creating a low carbon heat network won’t be easy to do, and it will involve some disruption, but it helps that it could start with a small number of big users.  Later, once it was all working well, the network could expand to provide low carbon heat to the wider community, giving us efficient, low cost renewable heat for decades.

The beautiful city of Stockholm has a massive district heating network with 3,000km of pipes supplying 800,000 homes using industrial-scale heat pumps to capture heat from a variety of sources.

We understand that more work is needed to decide on the best combination of heat sources, but we’re keen on Ground Source Heat Pumps. Although they’re expensive, they are even more efficient than Air Source Heat Pumps, so could reduce carbon emissions by a factor of 8 in comparison to gas boilers. They’re also virtually silent and invisible because, like an iceberg, most of the system is hidden below the surface.

This means that they can be ideal for historic buildings. For example, Jesus College’s recent decarbonisation project used a ground source heat pump network to replace the gas boilers in their Grade 1 listed, 12th Century buildings. The heat comes from 52 boreholes 140-150m deep under their cricket outfield.

Jesus College Decarbonisation

They’ve told us that although it made a considerable mess while doing the work, the reseeded grass will soon grow again……. and they took the opportunity to relay the cricket square whilst the area was disrupted!

Drilling the bore holes for a ground source heatpump

This will be a big project, and there is clearly still a lot of work to do, but we have a right to demand that the Council and University get on with it.

We’re facing climate breakdown, so future generations will not forgive us if we do not.