By Paul Homewood
The Telegraph article, which I posted on yesterday, noted:
A Government spokesman said: “A low carbon hydrogen sector here in the UK will be critical to delivering energy security, economic growth, and our net zero ambitions.
“We expect to have up to two gigawatts of low-carbon hydrogen projects in construction or operation by 2025.
“Hydrogen could play an important role in helping decarbonising heat in buildings, but the Government has been clear that a decision on this will not be made until 2026, allowing for full consideration of relevant evidence.”
The government’s Hydrogen Strategy aims at 5 GW by 2030. No firm decisions have been made about the balance between steam reforming and electrolysis yet, although it seems inevitable that the former will dominate. 5 GW amounts to about 4% of UK gas consumption.
But the real question is where the energy will come from in the first place, as hydrogen is not an energy, but an energy carrier.
Steam reforming, of course, typically needs natural gas to convert to hydrogen, but it is an extremely energy inefficient process. You would only get back about 60% of the energy you put into the process at the start. If it is to be low carbon, which is the whole idea, you will also need to add carbon capture, which also wastes energy. All in all, you would probably need to put in 2 units of gas, to get the equivalent of 1 unit back out.
At a time when natural gas is difficult to buy, as well as very expensive, it is plainly ridiculous to turn gas into hydrogen, which you will then burn instead of gas anyway.
But the alternative of electrolysis is also a dead end, certainly for the next couple of decades. The theory is that electrolysis will only use surplus wind power or other renewable electricity. But there is no such surplus currently, as all wind and solar power is sent to the grid. (The only exception is where it is constrained off, but this is usually due to the inability of transmission networks to handle it, meaning it would not available for electrolysis anyway).
Any demand for electricity for electrolysis, therefore, would have to come from a marginal source, which for many years to come will usually be gas generators. So the hydrogen will not be green at all, and production of hydrogen will simply end up increasing the consumption of gas. Again, because of the energy inefficiencies of both the electrolyser process and CCGT, more gas will be consumed to make hydrogen than will be saved by it being replaced by hydrogen.
None of this makes any sense from an energy policy perspective. Eventually of course we may have so many wind farms that there is theoretically enough renewable electricity to produce all the hydrogen we need, albeit hopelessly intermittently. But this prospect seems to be decades away.
To put things into perspective, a single 1 GW electrolyser would need all the output from a 3 GW wind farm. The new Dogger Bank wind farm project currently being developed is rated at 3.6 GW, and will be the biggest wind farm in the world with 277 turbines.
Even without all of the infrastructure and storage problems highlighted by the MPs, the idea that hydrogen will play more than a minor role in the foreseeable future is not a realistic one.
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December 20, 2022 at 09:58AM