Headlines exaggerate danger of hydrogen boilers

A front-page article in the Telegraph, and reports in several other papers including the Sun, Mirror and MailOnline, as well as specialist publication Recharge, claim that hydrogen boilers pose a greater risk than conventional gas boilers and could cause four times as many explosions and injuries. 

All the articles claim that hydrogen boilers could cause 39 explosions and 65 injuries or fatalities each year, compared to the nine explosions and 17 injuries or fatalities estimated to be caused by the natural gas boilers currently in use. 

However, this claim is missing several important pieces of context, which suggest that in practice, hydrogen could be an equally safe alternative to natural gas. 

Where do the numbers come from?

The reported figures come from a safety assessment conducted by engineering consultant Arup as part of the Department for Business, Energy and Industrial Strategy’s (BEIS) Hy4Heat initiative, which aims “to establish if it is technically possible, safe and convenient to replace natural gas (methane) with hydrogen in residential and commercial buildings and gas appliances”.

In particular, the articles use figures from two tables in the assessment, which show the estimated number of explosions and injuries that each gas might be expected to cause each year if they were being used in the same number of hypothetical homes.

These estimates are used to compare the explosive potential of the two gases, not to predict what would happen in the real world, where many conditions would be different. For instance, the report says that with natural gas, “the number of very large explosions predicted is greater than that observed in practice from historical incident reporting”. And with hydrogen, “The model has purposely been used in a conservative manner and is permitted to predict overpressures [explosions] much larger than will occur in UK domestic properties.”

The hydrogen estimates also assume that the gas is being used without a safety device called an “excess flow valve”. If these were installed as standard, the assessment estimates that there would be 26 explosions a year with hydrogen (instead of 39), causing 16 injuries or fatalities (instead of 65)—making it no more dangerous than natural gas.  

Burning natural gas can also cause injuries or death from carbon monoxide poisoning. As some of the newspapers point out, this risk would not exist in houses that use hydrogen instead.

Overall, the report itself states: “the actual risks associated with the use of hydrogen are expected to be lower than we calculate in the assessment.” And Hy4Heat says: “This assessment indicates that the use of 100% hydrogen can be made as safe as natural gas is when used for heating and cooking in certain types of houses.” 

A BEIS spokesperson told Full Fact: “Elements of this report have been cherrypicked when in fact, it concludes hydrogen can be made as safe as natural gas.

“All necessary safety assessments will be carried out and measures will be put in place to ensure that hydrogen is stored, distributed and used in a safe way.”

The Health and Safety Executive (HSE) wrote to BEIS after independently reviewing the safety assessment, stating it was satisfied that the assessment provided the basis for designing future hydrogen trials.