Hydrogen Storage–Call For Comments

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By Paul Homewood

I have received this request from Ralf Ellis, so I am throwing it out for comments:

Paul, I am about to send this email-letter off to Westminster, but was wondering if anyone has the expertise to check my work first. It is a critique of the Royal Society hydrogen cavern report.

House of Commons,

Re: Hydrogen Cavern Storage – Errors in Report.


You may have seen a report in the Telegraph that the UK needs 100 twh of hydrogen energy stored in caverns, to keep the lights on when we transition to unreliable Net Zero renewable electricity. This article was derived from a Royal Society (R.S.) briefing paper called Large Scale Electricity Storage.

Telegraph — Build hydrogen caves or risk blackouts.

Royal Society — Large Scale Electricity Storage Report.
See pdf enclosure below.

While I applaud the Royal Society for at last looking into energy storage, to compliment unreliable renewable energy systems, the costings in this paper simply don’t add up. They appear to have forgotten about wind turbine capacity factors.

The R.S. paper claims wind farms will cost £ 210 billion.
My estimate is they will cost £1,600 billion.

Plus wind turbines need renewing after just 25 years, so that is another £1,600 billion.

Total UK energy usage incorrect:
This R.S. paper is assuming average UK energy consumption of only 570 twh per year, which is less than half present energy consumption. Unless they have a good explanation for this reduction, all the other estimates and costings will be incorrect.

R.S. paper’s all-electric consumption 570 twh
Realistic all-electric consumption 1,280 twh

The government’s own UK Energy in Brief 2022 gives present UK total electrical supply as 320 twh per year, and indicates that electrical supply is just 20% of total energy consumption. Thus we will need to multiply present electric generation by four – to allow for transport, heating and industry – giving a total electrical consumption of 1,280 twh per year.

Prof David MacKay, a previous government science advisor, said much the same. He maintained that electrical generation needs to triple, to cover all energy demands, giving 960 twh. But this calculation was contingent upon heat pumps working for space heating in the winter, which I do not believe will happen. See Sustainable Energy Without Hot Air, by MacKay.

So how do they justify halving UK energy consumption?

UK Energy in Brief 2022

Sustainable Energy Without Hot Air

Note: See the note at the very end, regards the deficiencies in government energy data.

Wind energy costs incorrect (1):
This paper gives wind energy costs at £1 billion per gw, but this is a gross underestimate. See page 81.

The true costs can be gleaned from the Hornsea-3 windfarm in the North Sea, which is the largest wind farm in the world. Recent estimates put the cost for Hornsea-3 at £8 billion, and it has a max output (a name-plate capacity) of 3 gw. So that is £2.6 billion per gw of installed capacity, not £1 billion.

However, the true costs are even worse than this. A typical capacity factor for offshore wind power is only 33% – wind turbines are fickle energy producers, only working 33% of the time. So a 3 gw ‘name-plate’ wind farm like Hornsea-3, will only produce 1 gw of real energy on average.

So the true cost of Hornsea-3’s energy will be £8 billion per gw of actual electricity produced. That is 8x the cost estimate given in this Royal Society paper. That represents a massive miscalculation in costs.

Hornsea-3 windfarm costings

Wind energy costs incorrect (2):
There are more problems with these costings. This paper says that the UK will require 200 gw of wind energy to go Net Zero, which is yet another underestimate. See page 81.

In reality our average consumption of total energy (not just electricity) is 150 gw. Or about 1,300 twh annually. However, as already mentioned, a standard wind turbine capacity factor is only 33%. Thus we will need 3x the 150 gw consumption, or 450 gw of ’name-plate’ installed capacity, to deliver 150 gw of real electrical energy.

Actually, it is even worse than that. Because hydrogen storage is so inefficient – losing 60% of the power in the storage system – we will need 4x the 150 gw consumption, so that some extra energy is available to charge up the hydrogen ‘battery’. So our wind turbine installed capacity will need to be 600 gw, not the claimed 200 gw, and the true costs of wind power will climb in parallel with this. See page 13.

Since the cost of the 3 gw Hornsea-3 windfarm is £8 billion, the total cost of the wind system is:

200 Hornsea-3 windfarms £1,600 billion
Replacement after 25 years £1,600 billion
Total £3,200 billion (over a 50 year project)

Thus the total cost of all wind UK generation will be £3,200 billion, not £200 billion. And does the UK have sufficient continental shelf to place 200 Hornsea-3s around our coasts? Prof David Mackay thought not.

Hydrogen storage – energy incorrect:
This paper indicates that 100 twh of hydrogen storage is required, but a little note at the bottom says ‘thermal energy’. To convert this thermal energy into electrical energy we need to divide by about two – so this 100 twh storage system only contains 50 twh of electrical energy. According to this paper’s calculations, this is simply not enough to power the nation during wind and solar outages. See page 5.

50 twh represents 13 days of UK energy demand. But the paper is indicating that some months may have 20 or 30-day wind and solar outages, especially during the winter when energy demand is high. Plus some complete years have a 50 twh shortfall overall. Thus this stored hydrogen backup system is supposed to plug the usual daily and weekly gaps in unreliable renewable energy supply, and then plug the 50 twh annual gap too. In fact, the paper claims that an enormous 192 twh of storage will be required to ensure electrical continuity. That is 192 twh of real useable electrical energy, not thermic energy. See pages 19 and 21.

Reliable 24/7 electrical energy cannot be supplied to the nation, with only 50 twh of backup electrical energy.

Hydrogen storage – costs incorrect:
This paper claims that the hydrogen storage system will cost £100 billion. This storage system must be able to store 100 twh (or 192 twh) of real electrical energy. And it must be able to generate 150 gw of electrical energy, to power the entire nation when renewables fail. So this storage system requires the rebuilding of our entire present electrical generation system – four times over.

So we must build a completely new electrical generation system, using wind and solar. And then build another completely new electrical generation system, using stored hydrogen as a fuel. Despite the massive construction projects needed, there are still some Green activists who claim that renewables will be cheaper than nuclear or fossil fuels.

If we take Pembroke-B as an example, this methane gas powered generating station cost £1.6 billion in 2023 costs and generates 2 gw. So to power the UK with all its energy needs, we will need to build 80 Pembroke-Bs, at a cost of £130 billion. In addition we will need 85 clusters of 10 hydrogen storage caverns, at a cost of £325 million per cluster, plus all the associate pipes and pumps. Call that £40 billion. See page 40.

850 storage caverns £ 40 billion
40 gw electolyser £ 40 billion
power lines £ 370 billion
80 new power stations £ 130 billion
Subtotal £ 580 billion

200 Hornsea-3s wind farms £1,600 billion
Replacement after 25 years £1,600 billion
Grand total £3,780 billion

Note: The R.S. paper costs power-line upgrades at £100 billion. However, the UK’s entire energy system will need relocating to Cheshire and Yorkshire, which is where the backup salt cavern storage systems will be located. This will need a total readjustment of the National Grid transmission line system. And if the Greens clamour for HVDC power lines to save the environment, as they did in Germany, costs will escalate further still. The 800 km German Suedlink HVDC line will cost £10 billion, just for one 4 gw cable. Thus carrying 150 gw for 800 km in the UK would cost £370 billion. The total requirement for new transmission lines in the UK will certainly be more than 800 km.

The German Suedlink cable:

Solution mining caverns – costs:
This paper proposes the creation of 850 new salt caverns, in clusters of ten, to store the hydrogen. The size of these caverns is given as 0.3 million m3 per cavern, giving a total of 255 million m3 of hydrogen gas storage. Each cavern would store 122 gwh of hydrogen, giving a total energy storage of 100 twh. See pages 39 and 41.

However, I remain mystified by these claims and calculations.
Plus the report does not mention that much larger caverns already exist in this region.

The Atwick storage holds 315 million m3 of (methane) gas in eight caverns
Average 39 million m3 per cavern

The Aldborough storage holds 370 million m3 of (methane) gas in nine caverns.
Average 41 million m3 per cavern

The new R.S. storage holds 255 million m3 of (hydrogen) gas in 850 caverns
Average 0.3 million m3 per cavern (risibly small)

In other words, sufficient cavern storage already exists, and these facilities will be vacant when methane gas usage ceases. This Royal Society paper does not mention these caverns, but for what reason? I think the problem here is a large miscalculation – by two orders of magnitude.

I think the error can be seen in the quoted energy capacity of these new hydrogen storage systems. The older Atwick and Aldborough storage systems held methane gas for 20 days of gas supply each. Since methane gas is about half of total UK energy supply, this would equate to about 38 twh of stored energy in each each system. 10 years ago domestic boilers would have been 80% efficient, so each of these storage plants would hold 30 twh of electrical energy, when full of methane gas.

However, if we convert these caverns to hydrogen, they will contain less energy (presuming they are pressurised to similar levels). Hydrogen has 1/3 the energy content per m3 of methane, and half of that energy will be lost in electrical production. So the R.S. paper’s 850 new gas caverns would only hold a miserable 5 twh of electrical energy. This is only 1/20th or 1/40th of the backup energy required. (Note: hydrogen = 12 mjJ/m3, while methane = 39 mj/m3.)

Facility Volume Methane thermic Hydrogen thermic Electrical energy
Atwick 315 mm3 38 twh 12 twh 6 twh
Aldborough 370 mm3 44 twh 15 twh 7 twh
New caverns 255 mm3 30 twh 10 twh 5 twh

Since the R.S. costings for constructing these new caverns appear to be two orders of magnitude too high, I think there has been an error in the calculations somewhere. I think the R.S.’s 0.3 million m3 cavern-chambers, are supposed to be 30 million m3 chambers, which would then be a similar size to the Atwick and Aldborough chambers. This would make the costings and the energy content more realistic.

In summary:
The quoted size of the storage caverns is two orders of magnitude too small. However, the costings seem reasonable.

Fuels – calorific content chart.

Salt deposit and gas cavern storage in the UK

Note: This Salt deposit and gas Cavern Storage paper also contains a decimal error. It says that the “caverns range between 140 and 420 million m3”, when it should say that the “caverns range between 14 and 42 million m3. The total volume of the site is 315 million m3, so each of the eight caverns can only average 39 million m3 (not 390 million m3).

Salt mine hydrogen storage and leakage:
Hydrogen salt mine storage has been used at Teeside sine the 1970s, but on a small scale. The main problem of larger scale hydrogen storage is leakage and safety. Hydrogen is highly permeable and can leak through solid steel containers, when held at pressure. Although the saturated strata above these caverns will act as a hydrogen barrier, hydrogen being insoluble in water, diffusion and leakage through the cap-rock has been estimated as between 2-6% (Carden and Paterson, 1979, Pichler, 2013, Panfilov, 2016).

Needless to say, any seepage of hydrogen into surface buildings, would represent a serious fire and explosion hazard. Seepage of hydrogen gas is much more likely than seepage of denser hydrocarbon gasses like methane, which are far less permeable.

Underground Hydrogen Storage and possible seepage:

Compressed gas storage – CAES:
This paper indicates that CAES is the next preferred storage system, which stores compressed air in salt mines; while the heat produced by compression is held in molten salts or water ponds. This is not an established technology. The McIntosh CAES plant in Alabama used CAES but was found to be rather inefficient, so they now use the stored compressed air to drive a methane burning turbine.

If CAES with heat storage is not feasible, the McIntosh method of ‘hydrogen burning enhancement by compressed air’, could make hydrogen storage and combustion more efficient. This is fully explained in this Siemens brochure. It is a bit like supercharging a car engine, to gain more power.

Siemens Compressed Air Storage Solutions

Gas power with carbon dioxide capture:
This paper indicates that carbon-dioxide capture could be used for some backup purposes, with liquid CO2 being pumped into underground reservoirs for storage. However, what is to stop a Lake Nyos CO2 disaster, where 2,000 people died? If there was a CO2 well blowout during an anticyclonic weather pattern, everyone within 50 miles of the well would be suffocated. This could even happen with a North Sea well blowout, with the CO2 drifting up onto the east-coast and killing a few hundred thousand people.

Well blow-outs do happen, as we have seen in the oil industry, so there is no reason to think that CO2 drillers will be immune from such accidents. The only difference being that concentrated CO2 will hug the ground and asphyxiate everyone.

Lake Nyos CO2 disaster, where nearly 2,000 people died.

That is all for now.
I hope you find the information above useful.

Ralph Ellis
07948 309699

P.S. Please note: the energy units in UK Energy in Brief 2022 need amending, to reflect electrical energy used. At present this government information document is giving total energy consumption including generation inefficiencies, which is a nonsense figure, especially for nuclear power. We do not use the waste heat as it is literally a waste product, so why include it in ‘total energy used’. I had to subtract the thermal inefficiencies in each table and pie-chart, to produce an ‘electricity equivalent energy consumption’ figure. We will be all-electric in 2050, according to Net Zero, so we need ‘electric equivalent’ energy data.

UK Energy in Brief 2022

R.S. Large Scale Electricity Storage – link.

R.S. Large Scale Electricity Storage – pdf.

Image: The Lake Nyos CO2 blowout disaster.
Don’t let Green Carbon Capture do the same to York, Newcastle, or Teeside.

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