Bunhill Heat and Power – capturing waste heat from the London Underground

  • Case Studies
  • 18 July 2017

Islington Council are building a new energy centre in Bunhill as part of a pioneering project to capture waste heat from London Underground tunnels to help warm local homes and cut energy bills. The scheme will be part of Islington Council’s innovative Bunhill Heat and Power Heat Network, which already supplies more than 700 local homes with cheaper, greener heating.


*Please note that the above video is shared courtesy of Colloide Engineering, who have also published an article providing further information and video content on this project, here.


Bunhill II is the largest series three insulated pipe expansion in the UK, and follows industry best practice. It includes an innovative 1MW heat pump that extracts low-grade waste heat from the London Underground and reutilises it to provide heating and hot water – the first of its kind in Europe. The heat pump’s two-stage high-temperature refrigeration system (utilising a refrigerant that has no detrimental contribution to climate change or the ozone layer) works in tandem with a coil that can both draw heat from, or release cooling into the London Underground.


Co-located with the heat pump are two low NOx 237 kWe CHP gas engines that supply electricity to the heat pump (effectively a ‘gas-fired’ heat pump) and export electricity to the grid. As a result, the new energy centre provides demand response to the national grid by;

  • Consuming electricity directly (heat pump only operation)
  • Operating with no electrical load on the national grid (heat pump and CHPs both
  • Exporting electricity to the national grid (CHP only operation)


The current expansion of the network is being delivered in collaboration with London Underground, the Greater London Authority and Colloide Engineering. Bunhill II is being developed through Horizon 2020 and the EU FP7 framework. Through our work on the EU FP7 Celsius and Horizon 2020 Thermos projects, we have partnered with 35 different organisations, across 11 countries.


Based on the latest national grid carbon emission estimates, the network has a carbon intensity of 0.107kg/kWh.


A testimony to the sustainability of this network is that it has been developed whilst affording residents a minimum 10% reduction in their energy bills, with no public or private subsidy for the operational costs. In a time of exceptional public financial constraints and budget deficits, it is through collaborating with partners such as the Homes and Community Agency, London Underground, The Department for Business Energy and Industrial Strategy, Innovate UK and the European Union that they have endeavoured to keep these networks publicly-owned to ensure it is the public who benefits.


The network provides a customer-focused approach to energy; it is integrated into the core functions of the council and provides a high level of customer service. This includes unrestricted contact hours, four-hour response time for vulnerable customers (66% quicker than Heat Trust regulations) and an annual flat rate price to protect residents from volatility in global energy markets.


Ensuring that the network is future-proofed after every expansion provides an opportunity to scale the network and build on its 1,300 connections. As a result, they can achieve a connected heat transmission network, not only in Islington but across London, with the potential to connect to networks outside of Islington, in Hackney, Camden and the City.


The second stage of the network is being delivered as part of the EU-funded Celsius Project, which will deliver a blueprint of best practice to help cities develop replicable projects to evolve into energy smart cities. Working with the Greater London Authority and London Underground, the project will develop a detailed understanding of how networks can be integrated into the urban infrastructure, whilst utilising waste heat.


Sources: Association for Decentralised Energy & Global District Energy Climate Awards

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