London is looking to become net zero in 2030, under ambitious plans from the Mayor, Sir Sadiq Khan. Around two-thirds of the city’s carbon emissions can be attributed to heating and powering its buildings, but London offers a range of recoverable waste-heat sources that could support the supply of clean heat to homes and businesses – although these vary considerably by volume and temperature.
Consider energy-recovery plants, sewage-treatment works and data centres, which all emit large amounts of recoverable heat daily. Just one mid-sized data centre emits the equivalent amount of waste heat annually to heat around 100,000 homes.
Our work for the Greater London Authority (GLA), through the London Energy Accelerator funding programme, shows how waste heat could unlock the carbon conundrum. We identified and implemented improvements to the London Heat Map, to include data around available waste-heat sources – helping build awareness and identifying opportunities for developing low carbon heat offtake.
Our analysis considered the location and size of waste-heat sources across the city. By mapping this data, we highlighted a significant amount of waste heat already available in London. The largest existing sources contain enough energy to supply up to 12% of London’s heat – the equivalent of heating more than 600,000 homes.
The subsequent London Waste Heat Study1 examined the capital’s largest, most strategic waste-heat sources and modelled the opportunity for multi-borough heat networks development.
At a high-level feasibility stage, seven strategic heat network areas were identified by running analysis based on clusters of heat demand with size and proximity to these strategic waste-heat sources. If these potentially ‘viable’ heat networks were built, these seven areas could potentially supply up to 6% of the city’s heating needs after necessary development work. They also have expansion potential (Figure 1).
Multi-borough solution
If recovered (and ‘connected’ to heat pumps to lift temperatures where required), this waste heat could be used to distribute low carbon heat via district heat networks across multiple adjoining London boroughs simultaneously. This would successfully address one of the major challenges to delivering strategic-scale district heat networks – that is, the scale and complexity of providing a multi-borough solution.
To achieve this, considerable investment would be needed – specifically, the installation of around 487km of pipework. The cost would be around £2.3bn in capital expenditure for constructing the primary network in each heat cluster. Yet this investment in local energy provides considerable socio-economic opportunity and social value through associated local growth and jobs.
These seven strategic heat networks would also provide multi-borough solutions. To date, decarbonisation has mainly been considered borough by borough, as large-scale change and establishing the necessary delivery partnerships are challenging and time-consuming.
A strategic heat network programme aligned to waste-heat sources and the government’s zoning policy could enable the GLA to lead the way in demonstrating how the best of the public and private sectors is brought together. This could further unlock multi-borough zonal-scale heat network opportunities for cities globally.
The UK is looking at a new heat network zoning policy aimed at de-risking network development. The above-mentioned approach could offer greater confidence in securing heat network connections. Other large heat users – such as hospitals, universities and social housing providers – could also consider these heat networks to help decarbonise their estates.
The investment looks considerable, but this infrastructure has a lifespan of more than 60 years. Plus, waste heat is often available at lower cost than alternative low carbon sources. This makes heat networks more viable than ever for investors, giving customers more attractive tariffs and simpler technical solutions to decarbonising heat compared with other technologies. There is also the added value of improved air quality, energy security and significant emissions reductions.
Next stage
More needs to be done to realise these opportunities. At a high level, each of the seven strategic multi-borough heat networks identified were potentially commercially viable and deserving of further development work. The next stage involves looking at the findings in greater detail to better understand the technical and economic opportunities and business case. If these proceeded to commercialisation and construction, investment would be needed. This would probably be sought in partnership with the private sector – for example, the UK’s National Wealth Fund or the GLA’s Green Finance Fund.
None of this can be achieved in isolation. We will need to work with the GLA, London councils and boroughs, heat network developers and waste-heat sources, as well as several other stakeholders to unlock this opportunity fully.
Potential of heat networks based on waste heat
- Networks would cover 25 of the 32 London boroughs and the Corporation of London
- More than 7,900GWh per year of rejected waste heat, meeting up to 3,700GWh per year of heat demands, could be recovered, with potential for further recovery through infill and/or expansion
- Networks would save more than 40 million tCO2e over the next 40 years
About the author
Bill Wilson, associate director, Buro Happold
References:
1 Waste Heat Study, Local Energy Accelerator, GLA bit.ly/CJWHSBH25
