Hydrogen is likely to play an important role in the UK’s net-zero economy. It has been portrayed as a clean, abundant and storable fuel that could replace the fossil fuels that are currently used in transport, industry and our homes.

There is a strong case for hydrogen being used in sectors that are considered hard to electrify, such as heavy industry. For example, the cement industry is very carbon intensive and accounts for 7% of global emissions. Electrically-powered kilns for cement production are not technologically ready, whereas hydrogen could be used as a fuel to replace the coal and natural gas required to create the high required temperatures of 1450℃.

Our homes are responsible for 14% of the UK’s greenhouse gas emissions. This is mainly a result of burning fossil fuels for home heating. To get to net zero, we’ll need to reduce these emissions to virtually nothing. So could hydrogen help? Yes, in theory. When hydrogen is burnt, the main by-product is water vapour, so it’s much cleaner at point-of-use than natural gas.

Hydrogen-for-heating proponents argue that using hydrogen could make it easier to cut carbon from homes because converting homes to use hydrogen boilers could be less disruptive than installing alternatives such as heat pumps. However, following serious consideration, we think the evidence shows that hydrogen is unlikely to be feasible for heating homes at a large scale.

The UK already produces a significant volume of hydrogen, but the overwhelming majority of it is produced from fossil fuels such as natural gas – so-called ‘grey’ hydrogen. Globally, 99% of production is currently grey hydrogen and it is responsible for 2% of all carbon emissions. Although it’s low carbon at the point of use, the high-carbon production methods, and losses from transporting it, mean that grey hydrogen has twice the emissions of natural gas.

The potential of hydrogen to help decarbonise the economy rests on scaling up methods of production that create fewer emissions: so-called ‘blue’ and ‘green’ hydrogen.

Blue hydrogen is created by reforming natural gas with steam to produce hydrogen and carbon dioxide. The carbon dioxide then has to be captured and stored. The problem with this method is that carbon capture and storage technology has not yet been deployed at a large scale and studies show that significant emissions would still be produced.

Green hydrogen is produced through the electrolysis of water with the products created being just hydrogen and oxygen. This process is considered to be carbon neutral if the electricity being used is produced from a renewable source such as wind. This makes green hydrogen far more desirable than blue, if the goal is to cut carbon emissions.

However, currently there is no large-scale production of either green or blue hydrogen. The Climate Change Committee estimates that the UK could be producing 22-62 TWh of hydrogen annually by 2030, if the UK government targets for increasing production capacity are met. UK gas demand for home heating was 318 TWh in 2021, so even the highest end of the CCC’s estimate could heat just 20% of homes, if all hydrogen was used for this purpose. But, as noted above, there are many other sectors of the economy where hydrogen is likely to be needed, such as in decarbonising heavy industry. Moreover, only half of the hydrogen produced by 2030 is likely to be ‘green’. We believe this means that using hydrogen to decarbonise home heating, when alternatives already exist, isn’t a strategic use of what will be, for some time, a relatively scarce resource.

A boiler using green hydrogen uses six times more electricity than a heat pump to create a unit of heat.

This is mainly because large amounts of energy are lost in the form of waste heat when green hydrogen is produced and distributed. It’s estimated that 100 kWh of renewable electricity would provide 46 kWh of space heating and domestic hot water using a boiler running on green hydrogen.

In contrast, a heat pump can produce three units of heat – or more – for every unit of electricity it uses. So with the same 100 kWh of renewable electricity, assuming 10% of the energy is lost in transmission, a heat pump could produce 270 kWh of heat – nearly six times as much.

Obtaining enough green hydrogen for widespread deployment would require large increases to renewable electricity generation or a reliance on green imports. We would need five to six times as much renewable electricity to heat homes with green hydrogen as we would to heat them with heat pumps.

Currently it appears implausible that the UK can meet all of its hydrogen demand using non-fossil production by 2035. A strategic use of resources would be to maximise the value of low-carbon hydrogen available by focusing its use in areas that can’t be electrified, rather than using it to heat buildings.

Whether blue or green, the use of hydrogen for space heating in homes represents a high cost option for consumers. The capital cost of a hydrogen boiler is likely to be on a similar scale to that of a fossil fuel boiler, but the lower efficiency of hydrogen across its supply chain means that its operating cost will be more expensive than alternatives such as heat pumps. Analysis has shown that utility bills for consumers could increase by at least 70%, with a high likelihood that they could double. Blue hydrogen will remain an expensive option due to its reliance upon natural gas (much of which will have to be imported) and the high cost of capturing, using and/or storing the carbon dioxide emitted when producing hydrogen. Green hydrogen is assumed to cost between two to four times that of pre-gas-crisis prices due to its high demand for grid electricity or dedicated offshore wind farms.

Proponents of hydrogen for domestic heating often argue that hydrogen would be easy to adopt as it could make use of much of the existing gas infrastructure, the grid and our home appliances. However, this has not been proven at scale. Existing infrastructure can only be used for up to 20% hydrogen blended with natural gas, so all appliances that originally used natural gas, such as those for cooking, piping and even gas meters, would have to be replaced or modified. Preparation for ‘village trials’, which would see conversion of several thousand homes from natural gas to hydrogen, are raising additional considerations such as the need to add ventilation to all rooms. The cost of upgrading the gas networks and storage facilities is uncertain, but likely to be significant.

Although burning hydrogen doesn’t produce carbon emissions, it does produce nitrous oxides. These are pollutants that can cause respiratory illnesses. There is also some evidence that hydrogen plays a role as an indirect greenhouse gas itself. Hydrogen can deplete chemicals that typically reduce the lifetime of methane in the atmosphere, increasing methane’s global warming potential. This necessitates greater attention to the impact of leakages, as they may offset some of hydrogen’s benefits as a fuel for decarbonisation.

The UK government has committed to making a decision on the role of hydrogen for home heating in 2026. The rationale for this is to provide time to find out whether hydrogen can be viable, for example through the village trials mentioned above.

In our view, there’s already enough evidence to suggest that hydrogen is unlikely to be the best option for decarbonising homes. On balance, we think an earlier decision, that allows faster action on other technologies, would be better than waiting.

We also think that measures such as the proposed mandate on manufacturers to sell only ‘hydrogen-ready’ boilers by 2026 is unnecessary and potentially detrimental to decarbonisation efforts. Even if the government does decide to pursue hydrogen for home heating, it’s highly unlikely that hydrogen would be commercially available to homes before 2035, if at all. Given the average lifespan of boilers in the UK is 15 years, most hydrogen-ready boilers installed in 2026 would never use hydrogen. Introducing a mandate before even making a decision on hydrogen for heating would send mixed signals to consumers and installers and could potentially lead some to delay taking action that would be more helpful in cutting emissions – such as installing a heat pump or retraining to do so.