The Chief Executive of the UK’s Climate Change Committee is reported as saying that the UK would need to multiply its offshore wind capacity 30 fold in order to produce enough hydrogen to fuel domestic boilers. He appears to say that this therefore makes hydrogen impractical as a substitute for natural gas. I don’t think his number is remotely correct.

The CCC has always been a little sceptical about hydrogen for the obvious reasons that it is currently expensive and a switch to using it for domestic heating is a difficult and highly ambitious step.

In this case, its scepticism is overdone. To make enough hydrogen to completely cover the energy needs of all UK domestic homes currently using natural gas for space and water heating would require about 101 gigawatts of extra offshore wind, not the 300 gigawatts the CCC claims. (There is about 10 GW of offshore wind at the moment).

This is an important difference. The UK government is promising 30 gigawatts of new offshore wind in the next ten years so 101 extra gigawatts is easily conceivable. 300 is much more difficult.

By the way, we hydrogen fan-boys don’t argue for exclusive use of hydrogen in domestic heating. if we can electrify space heating using heat pumps we should do so. But heat pumps will not work effectively in many circumstances and hydrogen will therefore probably be necessary for some homes. It is well within the capacity of the UK offshore wind sector to provide the electricity necessary, despite the CCC’s statements.

Assumptions

Here are the assumptions behind my calculation.

1, Offshore wind capacity factor – 50%. (Probably a bit low for future wind farms but a bit higher than is currently achieved).

2, Electricity to hydrogen conversion factor – 70%. (Achievable today with a PEM electrolyser).

3, Requirement for total terawatt hours for domestic gas use – about 310 TWh. (Source: DUKES Energy for 2020)

4, Total offshore wind capacity required to provide 310 TWh of hydrogen – About 101 GW.

5, I have not added in the small amount of relatively extra energy needed to pump hydrogen through a network of pipes compared to natural gas.