Waste heat from Bristol’s sewers and possibly its disused mine tunnels are among the low-carbon sources that will be used to heat buildings in some parts of the city.
Local heat networks – also known as district heating – use a system of insulated pipes to take heat from an energy source and carry it to buildings.
(Image: Bristol City Council)
They deliver affordable, low carbon heat from a variety of sources and are fundamental to Bristol City Council’s drive to make the city carbon neutral by 2030.
The council’s ruling Labour group made two key decisions on March 3 which will enable it to expand the Bristol Heat Network, which at the moment heats more than 1,000 council homes in Hartcliffe and Redcliffe.
One decision means it can now accept a £10.2million government grant to expand the Redcliffe network and install a new one in Old Market.
Cabinet member for energy, Kye Dudd, said the Redcliffe network had delivered “massive savings” for residents of the blocks of the flats served, cutting their energy bills by nearly 50 per cent.
The council will use £6.6million of the Heat Network Investment Project (HNIP) funding to expand the network, which has been running since 2016.
The remaining £3.6million will be used to instal a heat network in Old Market, which will run off zero-carbon heat from floating harbour using the largest water-source heat pump in the country.
The Old Market network will supply a number of new commercial buildings, residential blocks and a school.
Cabinet also agreed the next steps towards creating local heat networks for Temple and Bedminster.
These two projects will cost £11.6million altogether, of which £5.2million will be sought from the Government’s HNIP fund, £4.9million is money the council has already borrowed, and up to £1.7m will come from connection charges.
Phase one of the Temple heat network will cost £5.4million and begin this year, with the installation of pipework and temporary gas boilers on Temple Island.
The network will use the waste heat from the cooling system of the new University of Bristol Temple Quarter campus and deliver it to new developments in the Temple and St Philips areas.
The first phase of the Bedminster heat network project, feasibility and design, will cost an estimated £6.2million.
The network will rely on an “energy centre” to supply heat from the main local sewer and possibly old mine tunnels in the area that have not been used for more than 100 years.
So the council will work with Wessex Water who own and operate the city’s sewer system and the Coal Authority who are responsible for the UK’s former mine workings.
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Geneco, a subsidiary of Wessex water, will likely install, own and operate the sewer heat pump.
The Bedminster network will initially supply low carbon heat to new developments being built in the area as well as existing buildings including Bristol South Pool, Holy Cross Primary School and adjacent social housing blocks.
Eventually, it could even heat nearby council flats and even individual homes.
But the expansion of the Bristol Heat Network is currently focused on new developments and large buildings, such office blocks and council estates.
The supply of individual homes is a few years away, and there are many that will never be suitable for connection to a local heat network.
These properties will likely rely on an air-source or ground-source heat pump in future, instead.
Heating homes and hot water is the city’s largest direct source of carbon emissions, Cllr Dudd told cabinet members.
The council is planning a system of local heat networks that will eventually replace the estimated 160,000 boilers in the city.
The largest will use waste industrial heat from Avonmouth and Severnside.