Hydrogen boilers work exactly like the gas boilers we use today, except the fuel is hydrogen instead of natural gas.

Hydrogen is the most abundant element. When it burns in pure oxygen, the only thing released is water. Air isn’t pure oxygen, though, so using hydrogen as fuel in homes isn’t quite this clean. While there will be no carbon emissions, burning hydrogen will still produce some of the other pollutants that are a by-product of burning natural gas, such as nitrogen oxides (NOx), a group which includes the gas nitrogen dioxide (NO2).

As with all low carbon technology, hydrogen boilers will be a good option for some households, but not others. As a general rule, heat pumps better suit homes that are energy efficient and well-insulated. From 2025, all new homes will have to be built with a low-carbon heating system installed. In such new properties, where the planning can take account of relevant costs and infrastructure, heat pumps are likely to be a good option. However, retrofitting heat pumps into older properties with different heating systems can be costly and disruptive. In these cases, a hydrogen boiler is likely to be a far less intrusive option, and allow insulation upgrades to happen at a later date.

Blended hydrogen is the interim step to moving to hydrogen boilers. This involves mixing 20% hydrogen with 80% natural gas. Hydrogen blend ready boilers are certified to run on a 23% hydrogen-blend, so introducing a mix at this proposed level would reduce carbon emissions by about six million tonnes a year.