Hydrogen Hype

So gas heating will be phased out. No gas boilers in new homes from 2025 and you will not be able to replace your gas boiler from 2035. Two options are being talked about as greener alternatives: heat pumps, running on clean electricity, and boilers adapted to burn green hydrogen.

To clarify: by clean electricity I mean electricity from wind or solar farms or from nuclear power (not very clean, since you have some very difficult waste to deal with, but at least there's no CO2 being produced); green hydrogen is made from water by electrolysis (or possibly from bio-waste, trapping the carbon) - NOT so-called grey hydrogen which is made from fossil fuels and produces CO2 or even blue hydrogen (same but the CO2 is captured).

electrolysis

The idea of simply switching our gas boilers over to hydrogen is an attractive one, especially if (i) you already have a boiler (and most of us do) and they've told you it will just need a couple of replacement parts, whereas heat pumps apparently cost £10000 plus and don't produce as much heat, or (ii) you happen to be running a gas company and can see yourself having to maintain thousands of miles of underground pipework and pumping stations for as long as anyone still has a gas boiler, even thought you are losing customers every day as they switch to heat pumps, and then you end up with a nationwide network of utterly useless infrastructure.

So, politicians, journalists and the bloke in the pub can all see the benefits of hydrogen, especially since there is the odd day when it's very windy or sunny and those wind/solar farms are churning out more electrons than we can use. Use the surplus power to turn some water into hydrogen and you've got yourself a tank full of free fuel.

Similar sentiments apply to powering cars. Petrol and diesel are bad but then battery-powered cars are expensive, have limited range and take forever to charge, but hydrogen...

But then if you are take the time to research it you see that it's not actually all that simple. Online news source Recharge recently published this comprehensive take-down of the idea of using hydrogen for heating our homes or fuelling our cars: ReCharge article.

The hydrogen molecule is very much smaller and lighter than the hydrocarbons in natural gas and this raises many issues concerning, pressures, leak-proofing, pumping pressure,... And h ydrogen only has around one third the calorific value of gas, so three times as much is required. These are some of the technical problems easily overlooked. Of course technical challenges can be overcome given enough effort and expenditure, but what concerns me more are the simple logistics.

Gas comes to our homes through pipes under the street which join bigger distribution mains radiating out from pumping/routing stations (equivalent to electricity substations). Most boilers will apparently run on gas with a small percentage of hydrogen mixed in, but to run on pure hydrogen we will need new boilers or new burners and control electronics in our old boilers plus, most likely, some improvements to the gas pipework into our homes. With hundreds of streets and perhaps thousands of homes being supplied from on substation, it is obviously not possible to switch houses or even streets over to hydrogen at one go. If we are not to be left without heat of cooking facilities, the switch will have to happen in a single day. Unless everyone can have their boilers (and hobs and ovens?) converted to somehow run on natural gas and then, overnight, on hydrogen, whole neighbourhoods and thousands of houses are all going to have the heating engineers in on the same day!

Now I am not dissing green hydrogen. On the contrary it is one of the most crucial components of a transition to a zero-carbon future. It's just that I think there are many better ways to use it than heating our homes. Energy is lost in converting surplus green electricity to green hydrogen by electrolysis; more is lost pumping it through the distribution networks; and the boilers themselves are rarely more than 90% efficient. Heat pumps on the other hand are readily available right now, use the green electricity directly and have efficiencies of around 300%. Similarly, we are already driving battery electric cars and vans (BEVs) which we can refuel at home, or at one of a rapidly growing network of charging points, directly with the electricity the motors need, but there are hardly any hydrogen pumps at filling stations, and having converted electricity to hydrogen the cars then require fuel cells to convert it back to electricity to actually run the vehicle.

Green hydrogen is one way of storing energy - as an alternative to battery farms, hydro-electric, gravity stores or other methods being developed. It may help us wean industry away from fossil fuels for energy-intensive processes like steel or cement manufacture. The shear weight of lorries and the distances they travel may make hydrogen+fuel cells a more practical approach than batteries. Similarly for shipping and for aviation where the weight of batteries is a major obstacle. Also, as well as hydrogen, electrolysis produces oxygen - another very useful commodity. So there is a great future for green hydrogen and applications that will make use of every kilogram that can be produced from surplus wind and solar. But heating our homes and powering our cars? I don't think so.