With the UK aiming for carbon net zero by 2050, decarbonisation of domestic and commercial heating will likely prove more challenging than making electricity fully renewable.
Currently, some 75% of UK households use natural gas boilers, but could geothermal energy prove a key step forward to turning the UK’s heating supply green and stabilising energy prices in the long term?
In this guide, we’ll look at how geothermal energy and natural gas compare, what the future holds for both energy sources and why we believe a natural gas boiler phase out is plausible but not overnight.
Geothermal Energy Vs. Natural Gas Explained
Natural gas as a source of electricity has fallen sharply over the past 15 years with renewable electricity generation surpassing 50% in the UK last year. However, it remains the norm when it comes to home heating.
Geothermal heating energy, on the other hand, has risen primarily in the form of ground source heat pumps or GSHPs, which are a domestic form of geothermal power.
This involves systems being installed at individual properties to generate home heating on-site. However, a small number of commercial projects also exist with future plans in the works.
Natural Gas Continues to Dominate Household Heating So Far
Natural gas has seen a marginal decline in use for home heating thanks to the installation of approximately 300,000 heat pumps in recent years, including close to 40,000 ground source heat pumps as well as increased gas boiler efficiency.
Nonetheless, for now, it remains predominant as a form of domestic heating and it will take significant developments and investment for geothermal power to supersede natural gas entirely.
It may take until around 2040 before low-carbon heating outpaces natural gas boilers and practical challenges may extend a full gas boiler phase out to around the 2060s (as an estimate). However, geothermal power and other low-carbon alternatives come with significant potential, which we’ll explore below.
One element that could contribute to the decline in natural gas boilers is the government aiming for new-build properties to feature only low- or zero-carbon alternatives such as heat pumps.
Options like air source heat pumps may play a significant role in the future of UK home heating, so going green won’t simply mean geothermal energy, with electric boilers likely to play a meaningful part.
The possibility of hydrogen boilers represents another potential alternative, though this is more tentative and speculative so far with significant infrastructural challenges and some safety concerns.
Commercial And Domestic Geothermal Energy
While natural gas boilers benefit from a well-established and regularly maintained supply and installation network, geothermal energy and air source heat pumps are garnering traction with substantial government backing and investment.
Domestic Geothermal Energy: Household Heat Pumps
As discussed, geothermal energy can be broken up into two categories. Domestic ground source heat pumps (which harness the Earth’s thermal energy on-site, installed at individual properties) account for just a fraction of household heating today. There are also several times more air source heat pumps installed than ground source.
There is a notable cost differential, however, with pricing estimates as follows:
- Air Source Heat Pumps – £5,000 to £14,000
- Ground Source Heat Pumps – £12,000 to £30,000
While the Boiler Upgrade Scheme and other government supports (eligibility varying depending on your region) could lower costs by thousands of pounds, further support and technological developments to increase efficiency and lower the upfront costs will likely be needed to increase GSHP installations nationwide.
According to GOV.UK, as of 2023, the UK is eyeing 600,000 heat pump installations per year by 2028 and an incredible 1.9 million annual instalments by 2035. That said, these targets may be challenging to reach, depending on how fast the roll out may accelerate.
Air source and ground source heat pumps will likely continue to grow in popularity over time, though how soon they might become as common as gas boilers is difficult to say, possibly taking until sometime in the 2040s, rather than the 2030s. That said, significant growth in the next decade is still feasible.
The Potential Rise of Commercial Geothermal Energy
While natural gas is supplied directly to gas boilers, commercial geothermal energy could supply properties and buildings with energy by drilling for geothermal energy resources beneath the Earth’s surface.
Unlike heat pumps, commercial-scale projects can use a geothermal well to harness subterranean energy and then resurface to distribute heat elsewhere, such as via a District Heating Network.
Should geothermal projects see further investment, commercial geothermal may see meaningful growth in the UK, helping with decarbonising heating sooner rather than later.
There are currently few active commercial geothermal projects in the UK, though a recently announced UK-French venture intends to explore a range of projects including non-vertical drilling to access geothermal heat.
The venture featuring a partnership between Veolia and Star Energy proposes providing heating through geothermal energy to district heating, hospitals, campuses, commercial buildings, and industrial processes.
Notably, the UK-French partnership is eyeing non-vertical or directional drilling as an effective and more innovative approach to accessing geothermal energy.
While many commercial geothermal projects drill directly down into the ground, directional drilling can offer access to locations that would otherwise be out of reach. Other benefits include the possibility of lowering drilling costs, limiting environmental harm, and enhancing heat transfer.
Verdict: Can Geothermal Power Replace Natural Gas?
Geothermal power could have a bright future in the UK with long-term goals of increasing heat pump installations (particularly with new-builds) and commercial projects. Indeed, the Veolia-Star Energy partnership could offer a blueprint for future UK-based geothermal projects.
Based on our speculative but informed and thought-out projections above, heat pumps (air source and ground source combined) would replace natural gas boilers in around twenty years, though geothermal energy itself would take a further decade, into the 2050s to achieve the same feat.
A range of low- and zero-carbon alternatives will most likely be required to offer a cumulative replacement to natural gas boilers as a means of heating homes and businesses across the nation.
Household heating later this century may be dominated by a combination of air source heat pumps, ground source heat pumps, electric boilers, and commercial-scale geothermal energy. Hydrogen boilers may also play a meaningful role in the future, though this is more up in the air.
While speculative, it’s entirely possible that fully phasing out natural gas boilers could extend to 2060-2070, though a phase-out by 2050 could be viable depending on how much carbon-free alternatives take off in the 2030s and 2040s.
All in all, geothermal power has every chance of becoming a significant source of heating in the UK in the coming decades and the UK-French venture discussed earlier could be a key starting point on a commercial level. Renewables in general will likely help decarbonise the electricity grid and home heating substantially in the near future.
