Heat networks and the trilemma

 When politicians talk about the ‘energy trilemma’ (carbon emissions, security of energy supply, energy costs) facing the UK, most people focus on electricity and, more specifically, on “keeping the lights on”.

However, if we take a look at what we actually use energy for, “keeping the lights on” is a relatively minor element of the energy landscape. Indeed, 85% of the energy we use is for heat and transport, with lights and appliances some way behind at 7%. So perhaps the energy crisis strap line should be recast as “keeping us warm and moving”.

The carbon emissions portion of the trilemma is particularly important as it sets the underlying agenda for our future energy landscape. In the UK we have made a legally binding commitment to reduce CO2 emissions by 80% by 2050. Given that over half of our emissions come from heat and transport, we are going to have to radically reduce the emissions from these two areas in order to deliver on that commitment.

With transport, although biofuels may be part of the mix, electrification is the only credible long-term option for decarbonisation. This has profound implications for power generation, transmission and distribution infrastructure in the UK. Indeed, we will require a multiple of the power that we currently need for lights and appliances – and all of that new capacity will need to be low carbon.

“While there are advances that we can be making in building efficiency, the great majority of the housing stock that we will have in 2050 is already built.”

Which brings us back to heat. Heat represents over 40% of end use and a third of our carbon emissions. While there are advances that we can be making in building efficiency, the great majority of the housing stock that we will have in 2050 is already built. In a nutshell, this means that the opportunities for reduction in heat demand are limited.

Which all means that we will need to reduce the carbon intensity of heat.

While it is likely that the electrification of heat will be a part of the solution, it is extremely unlikely that we will be able to generate and distribute sufficient quantities of low carbon electricity to permit large-scale electrification of heat, particularly for our existing stock.

Which brings us to heat networks.

The use of heat networks is increasingly being recognised as a critical component of the UK’s future energy landscape. In addition to not requiring a massive overhaul of electricity infrastructure, heat networks address all three aspects of the energy ‘trilemma’:

• Carbon emissions: heat networks enable the use of a wide range of low carbon and renewable heat sources
• Energy security: heat networks enable diversification of energy sources
• Energy Costs: Heat from district heating can be delivered at a cost below that of gas boilers and electric heating.

And importantly, unlike other more speculative technologies, we have examples from other countries (primarily Scandinavia) where heat networks have successfully been deployed on a large scale.

Which all goes to explain to why DECC is throwing its weight behind the development of heat networks, with the announcement of £300m of funding for heat networks announced in the autumn statement.

Given estimates that up to 43% of the UK’s heat could be economically delivered via large-scale heat networks, coupled with a political will to push in this direction, it is likely that heat networks will be a prominent feature of the future energy landscape. Indeed, DECC estimates that up to 20% of heat will be delivered via heat networks by 2030.

Given that only 2% is currently delivered via heat networks, this represents a significant restructuring of the largest portion of UK’s energy landscape.

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