Why hydrogen heating?
Heating water with electricity is the most effective thing you can have. If you first start producing hydrogen with residual electricity and then start generating electricity again from hydrogen. Do you have a lot of loss.
I’d rather say if you have power left, use it to preheat a second or third buffer (I don’t know how area heating is created). So you have more hot water at your disposal. Especially if you insulate it well and the tank is big enough, it will take some time before it cools down.
For buses, the best trolley buses. Also saves another rotation step. With a small battery inside it can drive 10 km without lines, if there is a piece in maintenance or something else. It is not stuck.
Gas replacement? Maybe for factories, but for home/garden/kitchen using a water pump is more reasonable. Induction cooking is more efficient than gas (or hydrogen) can achieve.
I don’t see the point of hydrogen that way. If you want to use it as a ‘battery’ I prefer making a gravity battery like tank where you pump water from the residual stream and use it in the moments you need it. Connect this tank to a river or canal and have two types of power supplies.
One disadvantage of hydrogen is that it takes a lot of energy to make. It is very volatile, even in a hydrogen tank there is always something leaking. Because hydrogen is very small.
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