Cambridge market: Will boreholes be dug under cobbles for district heating scheme?

A scheme to dig boreholes underneath Cambridge’s market square is being considered, with the aim of creating a new green heating system that would free the city centre from relying on gas.

Cambridge City Council has come up with the proposal to dig deep shafts in the square when it takes up the cobbles in the market to have them reset.

The University of Cambridge, which has experience of district heating at its Eddington development, is partnering with the council to explore the idea.

The Guildhall and Corn Exchange, which are both council-owned, as well as surrounding buildings could use the new district heating network in a bid to protect them from rising fuel prices and reduce carbon emissions. Holes could also be dug in green spaces around Cambridge – such as Parker’s Piece – as part of further ground source heat pump plans, which could supply heat to Parkside Pool.

Concerns have been raised by the Cambridge Market Traders’ Association that the project could leave them displaced from the market for long stretches of time and that people could lose their businesses.

Cllr Rosy Moore (Lab, Coleridge), executive councillor for climate change, environment and city centre, said: “We’re in a climate crisis so we need to change the way that we heat our homes, offices, shops, and all of our buildings.

“Obviously, the war in Ukraine has highlighted how we don’t want to be dependent on gas from unfriendly countries. So that’s the reason to look at having ground source heat pumps. And the reason we’re thinking of doing it in line with the market square project is that if we’re already digging up the square to reset the cobbles then it’s the best time to look into it when we could do the two projects together.”

A university spokesperson told the Cambridge Independent: “The University of Cambridge is partnering with Cambridge City Council on the application for funding for the feasibility study for a city centre heat network. The feasibility study will look at the potential for boreholes – and other heat sources – in a range of locations and will need to take account of what’s under the ground.”

A pilot scheme for a ground source district heating system that can be retrofitted to old buildings is already under way at Swaffham Prior, a village on the outskirts of Cambridge. It has so far attracted around £3million in grant funding, but around £9m is projected to be spent by Cambridgeshire County Council on the project.

Cllr Moore added: “Wouldn’t it be fantastic if, with all of our green spaces for example, we could make the most of them and provide sustainable heating to our swimming pools and our buildings?”

When asked whether the council was considering digging on Parker’s Piece to install heating for Parkside Pool, Cllr Moore said: “I think we should, yes, be looking at a variety of options across the city.

“We’re just looking into the possibility of where we could have them in the city, either working ourselves or with the university.”

However, Bill Proud, secretary of the Cambridge Market Traders’ Association, was alarmed. He said: “This is the first we have heard of it and it is a huge worry that we could be kept away from the market and sent to some far away location while this is done – previously the council has suggested Cowley Road – which would spell

disaster for our businesses. The market is people’s livelihoods and does so well because it is sited next to one of the UK’s most popular tourist attractions, King’s College Chapel.

“What do you think the feasibility of this project will be if it means closing town centre shops too? And if they are going to do this, what is the timescale?”

Documents going before the city council’s environment scrutiny committee today(March 24) show that a project team, which is working on renovating the market and finding removable stalls that can be taken down to make way for events, is looking at the heat source plan.

They have been considering sources for green energy in the market but have decided that “with limited scope for solar or wind, and the challenges of retrofitting historic and listed buildings in a compact city centre, a renewable heat network is likely to be the major component and only viable means of decarbonising a historic city centre with many listed buildings, including buildings owned by the city council, including the Guildhall and the Corn Exchange.”

The documents add that the market square redevelopment proposals “raised the question about the opportunity to incorporate boreholes into this important public realm, to help contribute to the supply of renewable heat, for example to the council’s Guildhall and Corn Exchange.”

The report reveals that a “basic calculation” has been done by a heat pump supplier to determine the possible heat load achievable from this area alone and it was found that a large percentage of heat could potentially be provided from this site. However an additional heat source is still likely to be needed and it would not provide a surplus to help heat the New Museums (Zoology Museum) site, which is owned by the university.

The team is proposing that the market square is one of the areas considered as a potential heat source as part of the national Heat Network Delivery Unit (HNDU) study, so that “we can explore in more detail the technicalities and difficulties of this site”.

A separate project team is also working on a bid to the government’s HNDU to fund a feasibility study for a Cambridge City Centre heat network. The bid will be submitted “in spring 2022”, according to the meeting papers, and it is hoped it will establish the feasibility, test options for future expansion, and prepare for further funding bids for detailed project development, as well as considering the linkages to a market square project.

Officers say in the meeting report that “a district heat network would be a major step forward in decarbonising the historic city centre and the market square could provide a significant contribution”.