More than 80% of the UK’s heat is easy to decarbonise. What’s stopping progress?

Figure 1: The UK’s energy use by sector (data from DUKES).

Like many parts of the world, the United Kingdom (UK) has made some good progress on decarbonising electrical power generations and is make good “in-roads” into the electrification of transport.

But it appears according to the latest report by the UK’s Climate Change Committee that progress has stalled.

Worse still, also similar to other regions, the decarbonisation of heat is showing much less progress, despite heat being half the challenge (Figure 1).  Why is this so?  First let’s dig into to the available data on energy consumption for heating.

Figure 2 uses Digest of UK Energy Statistics (DUKES) data that provides a breakdown of energy use by type to derive an energy use for three temperature ranges.  It is assumed that all combustion fuels (mainly fossil oil, gas and coal) are for heating.  Each sector is demarcated as one of three temperature ranges

• Low: Less than 80 ºC (typically space heating/cooling and domestic hot water), but may include some lower temperature process heat.
• Medium: less than 150 ºC – typically very similar to Low, except that there is use of process heat greater than 90 ºC, often in the form of steam. Our research into these sectors indicates that although significant and most often required, the temperature range from 120 to 150 ºC is the minority of energy use om the sectors grouped in this category.
• High: greater than 150 ºC – typically these sectors have heat demands of several 100s ºC to drive chemical reactions in mineral, cement, metals and oil & gas refining processes.

It came as some surprise to us that as much as 90% of the UK’s heat demand is less than 150 ºC and therefore well within the output capabilities of heat pumps.  We were less surprised by the dominance of domestic heat which is typically 60 ºC or less.  Homes use just over half of the UK’s heat demand.

We have learnt over the last few years that much industry is substantially lower temperature than the obvious higher temperature processes such as cement and metals manufacture, but those higher temperature facilities are also typically the highest loads as well – measured in 10s MWth. The UK’s commercial and industrial sector is using a lot of heat energy, but it turns out that the majority of it is much easier to decarbonise than we first perceived.

This is good news all round, as we can get on with electrifying with heat pumps the majority of the UK’s heat load now.  It also provides focus for the development of high temperature renewable heat from biomass, biofuels and green hydrogen to deal with the truly hardest to abate sectors.

Figure 3: Geothermal heat pump applications

Figure 3 shows the range of heat temperatures can supply to the target or “sink”.  Conventional domestic geothermal (or “ground source”) heat pumps (~10 KWth in capacity) are usually more than able to provide both space heating for thermal comfort and domestic hot water (typically around 60 ºC).

Therefore, these applications can be (and are) extended to larger thermal outputs capacities (100s KWth to greater than 1MW in larger heat networks).  Hence already more than 70% of the heating in the UK could be delivered by this proven technology at high heat pump efficiencies (known as the Coefficient of Performance, COP) of 3 or more.

The barriers to large scale deployment of this proven, low temperature low/zero carbon solution have included fossil fuel prices, lack of climate ambition, inability to cover high upfront capital costs and basic lack of awareness of the technology and its range of applications.  Apart from the lack of awareness barrier, there has been substantial shifting of all of these barriers in the last few years.  There is work still to be done to educate and engage with consumers and policymakers, although there is rising interest in government both at committee level and from individual politicians.

The apparently binary decision on heat in buildings which has now been delayed to 2026 has seemed to disabled action to accelerate electrification and favours the incumbent (gas).  We agree with many that some simple schemes that favour the adoption of efficient heat pumps are needed, especially to catalyse the early stages of diffusion of this proven clean tech.  Contract for Difference (CfD), Feed in Tariff (FiT) or Contracts for Benefit (CfB) measures to add financial incentive to consumers to adopt electrification over gas are needed, at least for the pioneers and early adopters.

We believe the best way to accelerate deployment, is to educate and engage with real projects.  Starting the deployment learning curve will also drive down costs and provide the opportunity for innovation, learning and performance improvement.  We should focus on focus on lower temperature applications first, which for geothermal sources, generally means relatively shallow boreholes and no or negligible risk.  This gives the UK’s nascent geothermal development and drilling industry the opportunity to build capability on commercial projects while taking opportunities to push the envelop on performance and on occasion drill deeper.

As well as measures to support widespread adoption of proven technology, we also see the opportunity for some kind of innovation funding to support consumers with larger scale demands take the first step.  We have a number of First of a Kind projects, which are nevertheless low risk, that could benefit from “mutualization of risk” with material capital cost sharing by government.  We believe that these “pathfinder” projects will lead the way for accelerated adoption across multiple sectors.

Higher temperature heat pumps of MW scale are already on the market and development of the technology is ongoing.  These industrial heat pumps currently typically use fossil fuel process heat that would have been wasted previously, but we see that other sources of thermal energy such as solar, water bodies and of course geothermal are an underutilised option to more completely substitute out the fossil fuels.

Where deeper geothermal resources are present and de-risked, the additional temperature with depth certainly adds to the energy balance of the resources.  Our research into the levelized costs which remains the best way of assessing the impact of both capital and operating costs, shows that it remains important that drilling costs are minimized. Hence we see the geothermal decade in the UK as getting into action first on shallow resources and then progressing with much drilling and other technical learning under our collective belts delving deeper in our development of geothermal heat.

Our mission at Causeway Energies is focused on the decarbonisation of larger demand heating (and cooling) in the sectors described in this article. We are building a portfolio of clients in the commercial, industrial, public and heat network sectors in the UK, Ireland and elsewhere. We are also developing leading edge technologies to improve the bandwidth, efficiency and cost effectiveness of geothermal + heat pump applications.