The original network, Bunhill phase 1, is powered by a Combined Heat and Power (CHP) engine at an energy centre in Central Street. This CHP engine is powered by gas and uses heat created from producing electricity to heat buildings and provide hot water. Unlike normal electricity production that wastes up to two thirds of the fuel used to make it, the waste heat the CHP generates is captured for the heat network.
The success of Bunhill phase 1 encouraged the council to extend the network. As the principal design and build contractor, Colloide were responsible for the revolutionary Bunhill 2 Energy Centre the first of its kind in the world!
The new energy centre uses state-of-the-art technology on the site of a disused Underground station that commuters have not seen for almost 100 years. The remains of the station, once known as City Road, have been transformed to house a new 500Kw ammonia heat pump driven by the heat recovery from a heat exchanger coil within a London underground shaft, recovering the warm air lost throughout the northern line tube.
In addition, the two-metre fan, installed in an existing six-storey London Underground mid-tunnel ventilation shaft, can also be reversed to help with cooling the Tube tunnels in the summer months. The utilisation of two natural gas CHP units with a combined output of 700Kw and district heat pipework of 1800m’s allows a further 550 homes and a primary school to be connected to the existing Bunhill Heat and Power district heating network which was launched in 2012.
The heating bills for council tenants connected to the network will be cut by 10 per cent compared to other communal heating systems, which themselves cost around half as much as standalone systems heating individual homes. The district heating network commits to the UK’s net zero carbon target by 2030 as it reuses heat that would otherwise be wasted; those who are connected will be helping to reduce CO2 emissions by around 500 tonnes each year.
Many major cities across the UK and around the world have underground railway systems, all of which need to vent heat to ground level, so there is a huge amount of potential for this project to be replicated across the globe.