The importance of flexible heat networks in meeting our 2050 climate targets

Published by Saskia Barker 27 / 02 / 19

The UK will not be able to meet it’s 2050 climate targets without decarbonising heat. According to a 2016 report from the Committee on Climate Change (CCC) 20% of UK carbon emissions come from heating and hot water for buildings.

While UK electricity generation has been steadily moving away from fossil fuel sources in the last few decades, natural gas continues to make up the vast majority of the fuel used for heat in the UK.

You may have read about a recent report from the CCC which recommends that the UK ban new build houses from connecting to the gas network in the next six years. 

The CCC estimates that 18% of UK heat demand will need to be met by heat networks, also known as district heating, if the UK is to meet it’s 2050 climate targets. Currently they make up 2% of UK heat demand. They are particularly suited to areas where there are a lot of buildings with heating requirements in one area.

While currently the majority of the heat networks in the UK have natural gas boilers as their primary input, heat networks are flexible, and once the network is in the ground, inputs can be added and replaced. Heat networks with CHPs or heat pumps are particularly interesting because not only can they help UK heat consumption decarbonise, but they can also help National Grid balance the electricity system.

The electricity system has changed significantly in the last 15-20 years. More and more of our electricity is generated by renewable sources which can be unpredictable and might not be generating when we need it. And all the remaining coal power stations must close by 2025. The way we consume electricity is also changing. The increase in energy efficient lighting and appliances has changed the size and shape of national electricity demand and it’s expected to change more with the move to electric vehicles. These changes are making it more difficult for National Grid to balance the system. This is creating a dramatic new opportunity for flexible energy users and distributed generation to help National Grid meet the energy demands of the UK and support the renewable energy revolution. According to Aurora Energy Research, in a flexible system, reaching 70-80% renewable production by 2050 is the cost-optimising option, with no new nuclear beyond Hinkley Point C needed to meet carbon targets. In a less flexible system, more than 40% renewable production by 2050 increases the cost to consumers.

Heat networks are inherently flexible. The physical network itself has a certain amount of thermal inertia and adding thermal stores can greatly increase it. This inertia means that heat networks can use heat pumps to increase their demand at times of high solar output when National Grid needs it or turn on a CHP when there isn’t enough generation on the system.

Gateshead District Energy Scheme is an example of one of the heat networks already doing this. They’ve been working with Flexitricity since 2016 and were the first I&C customer to enter the Balancing Mechanism - the main tool National Grid uses to balance the electricity system. The CHPs at Gateshead are instructed on by National Grid when they’re not already running in exchange for payment. The extra heat generated is put into the network. Similarly, at times of excess generation on the system, the CHPs at Gateshead can be instructed to turn off by National Grid as an alternative to shutting off windfarms. The thermal inertia in the network and the heat stores means that this can happen for the 20 minutes to an hour that are required by National Grid without the heat customers noticing. A heat network with a heat pump could offer the same services to National Grid.

The government’s Heat Network Investment Programme has funded a number of interesting, innovative heat network projects recently. If the UK is going to meet its 2050 climate targets it’s important that this programme continues and is expanded so that more urban areas install heat networks, and more heat consumers move onto them. At the moment, natural gas CHP offers a lower carbon alternative, but in the next 20-30 years hopefully there will be more even lower carbon sources of heat used for the majority of heat networks like heat pumps, energy from waste, and waste heat from industry.

It’s also crucial that flexibility becomes a fundamental design consideration for all future heat networks, so they can not only play a part in the low carbon future of heat, but also help support the decarbonisation of the electricity system by offering their flexibility to National Grid and possibly the Distribution System Operators of the future.

Image sources:

Gateshead Energy Company

Financial Times:

Association of Decentralised Energy (ADE) Market Report on Heat Networks in the UK

Saskia Barker

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