Heat accounts for around a third of UK Green House Gas (GHG) and nitrogen oxide (NOX) air pollution emissions. 50 per cent of heat emissions come from the domestic sector, 20 per cent the commercial sector and 30 per cent the industrial sector in the UK. 98 per cent of domestic GHG emissions from heat come from space and water heating in the UK. In 2015, fossil-fuelled boilers generated 88 per cent of space and water heating. The Government's 'Clean Growth Strategy' sets out the important role that heat networks will play in meeting our climate change commitments in support of the UK's legally binding target to reduce greenhouse gas emissions by at least 80 per cent in 2050.
District energy networks form a part a key part of the city's policies on energy security/local energy supply, reducing costs and decarbonisation but also supporting regeneration. By linking buildings using heat pipes, heat or cooling (or power) can be provided in a more efficient way and utilise a range of heat sources, including 'combined heat and power', renewable sources and waste heat, allowing flexibility over time. Plymouth City Council recently published a city-wide District Heating Strategy setting out the opportunities.
Plymouth is participating in a European funded project called HeatNet NWE, together with project partners from Ireland, UK (Scotland), France, Belgium and the Netherlands exploring the use of fourth generation or smart approaches to district energy (4DHC). The project has funding from the European Regional Development Fund of the European Union, under the Interreg NWE Programme 2014 to 2020 with support until 2021
Fourth Generation District Heating and Cooling networks have a number of characteristics, which include:
- Ability to supply low-temperature district heating for space heating, domestic hot water and cooling to existing or new buildings
- Ability to distribute heat and cooling in networks with low thermal losses
- Ability to recycle heat from low-temperature and waste sources and integrate renewable heat sources such as solar, geothermal and marine (water source) heat
- Ability to be an integrated part of smart energy systems (in other words integrated smart electricity, gas and thermal grids)
Plymouth is one of the pilots to demonstrate the application of this approach.
A Plymouth 4DHC Transition Roadmap sets out the specific opportunities for Plymouth over the short, medium and long term.
The construction of Plymouth City Council's 5th-generation district heating and cooling (5DHC) network started in 2019, in the city centre. It started with the drilling of the first well into the aquifer that flows through the limestone strata on which areas of the city are built. The ultra-low temperature network will allow usually rejected energy to be recovered and shared within, as well as between, buildings that are heating and cooling, simultaneously reducing primary energy and increasing system efficiency.