As previously mentioned, Prof Jack Ponton represented SAS at the Scottish Parliament Cross Party Group on Renewable Energy and Energy Efficiency (SPREEE) on 2 March. He has written up his notes for us in an easy to follow and humorous format (below. ) Enjoy!
Holyrood Meeting: Role of Hydrogen in Domestic Heating – 2 March 2021
This was a meeting of a cross party group of MSPs with three presentations followed by a question and answer session. The presenters were all people with a vested interest in renewables in general and/or hydrogen in particular.
Nigel Holmes of the Scottish Hydrogen and Fuel Cell Association, a body which clearly exists to get grants for its member companies, described projects which are underway. There are more of these than I was aware of, although it was not at all clear how much of what was described is happening, funded or merely hoped for. The projects all involved wind generated electricity and electrolysis. I can’t and won’t give detailed descriptions but all involved some storage, hydrogen powered vehicles and domestic heating. They are as follows.
In Fife, mainly concerned with domestic heating, of which more below. In Aberdeen which currently has the only hydrogen fueling station in Scotland which so far mostly involves hydrogen buses; I believe that the hydrogen available to date is actually hydrocarbon derived. In Cromarty where hydrogen would be used for heat in distilleries.. In Orkney and Shetland, these being the most ambitious including hydrogen powered ferries and with ambitions to export hydrogen by ship. There may be a better rationale for the island projects due to their distance from the rest of the country and sometimes unreliable connections, both physical and electrical. They certainly will have have a potential excess of electricity over their local needs.
The second presentation was from Scottish Gas Networks (SGN, presenter not listed on the agenda and I didn’t note it.) and focused on domestic heating, in particular a demonstrator and potentially a pilot study in Fife. SGN’s interest in promoting hydrogen for heating against the alternative of electrification is clearly because their assets are the pipes which carry gas around the country and to consumers. The local networks ought to be suitable for hydrogen distribution but the longer distance high pressure network would need replacing as the steel used is unsuitable for handling high pressure hydrogen.
It is proposed to ban the installation of natural gas boilers in new build properties from 2025 and the Fife projects, along with one in Leeds, are to assess the feasibility of replacing them, and other appliances, with hydrogen fueled ones. Hydrogen boilers are still experimental and hydrogen compatible natural gas boilers which are seen as a key requirement for transition are even more so. A longer term change over to hydrogen nationwide seems frankly impractical. Comparison with the previous switch from coal gas to methane is flawed; there are simply so many more gas appliances installed now.
For me the most significant bit of information in this presentation was one of the first slides showing seasonal gas demand. All my previous work has looked at electricity based on present demand patterns where the UK peak demand rises from about 30GW in the summer to occasionally nearly 50GW in winter. I had never appreciated that while summer gas demand is also about 30GW, winter peaks can be 180GW, six times as much! This has very profound consequences.
A key issue for hydrogen is storage and the amounts and methods were not described in any of presentations. Graphics of small scale storage suggested compressed gas. Graphics of ships exporting hydrogen from the islands made them look like LNG tankers. Large scale storage and transport of hydrogen as a liquid is in principle possible but is harder than transport of methane due to the much lower boiling point and liquid density of hydrogen. I am not aware that anyone actually transports liquid hydrogen at present.
The SGN presentation spoke of storage in porous rock strata which do exist in central Scotland. the actual feasibility of this and capacity available are still speculative, but I found a paper which mentions a medium-large scale figure of 700te of hydrogen. which would represent 28GWh. This would correspond to about a day and a half of average consumption for 1 million households.
I’ll say more about the storage issue later.
The final presentation was from Richard Dixon of FoE who until recently had a weekly environmental propaganda column in The Scotsman. It started predictably with a harangue about how ‘pledges’ by most countries to reduce emissions were not being honoured and so ‘we’ must decarbonise as quickly and completely as possible. (Notwithstanding that total elimination of the UK’s 1.3% contribution to world emissions would have an immeasurably small impact on global climate.) I was about to go and pour myself a gin and tonic (the great advantage of Zoom meetings) when something in his style of delivery made me pause. After expanding on how useful electrolytic hydrogen was for all sorts of things which could contribute to saving the planet, he said that the last thing it should be used for was domestic heating. He did not make the point, which I’d intended to raise in the Q&A session, that it would always be more sensible.to use electricity for heating directly rather than to convert it to hydrogen (at 70-75% efficiency) and burn that. Must be the first time I’ve ever agreed with him. His solution to domestic heating was heat pumps.
The Q&A session was unmemorable and rather chaotic. Heat pumps came up again with an incorrect claim that air source heat pumps could be retrofitted to any building. This is misleading.To get good performance from any type heat pump the building really has to be designed or extensively modified to allow a large heat transfer area to compensate for the lower temperature a heat pump can achieve with good efficiency. Air source heat pumps do not perform well in a Scottish winter. I don’t believe I’d be allowed to put an ugly, noisy air source heat pump on my B-listed tenement flat in a conservation area.
I had prepared two questions but couldn’t find the button on Zoom which raises a hand. In any case I think the chairman only took questions from the committee as there were many hands still raised at the end of the meeting. However here are the intended questions and my thoughts.
Given that power for electrolysis will be available only intermittently, it will be necessary to store hydrogen. How much will have to be stored to provide security of supply and how will it be stored?
I had tentatively estimated that to cover a typical wind lull of up to a week (as I write this on Friday 5 March we are still in one which started last Saturday) would require 75 million standard cubic metres of hydrogen to supply the gas consumption of one million households. To the best of my knowledge the only large scale hydrogen storage facility is on Teeside and is just one million standard cubic metres.
However, I calculated this using the average household gas consumption over the year of 12MWh. The revelation by the SGN speaker that winter gas consumption is six time that in the summer storage requirements for a winter lull would be very much greater.
As to the ‘how’ only underground storage would be remotely practical. As mentioned above, appropriate geology does exist in Scotland but actual feasibility has yet to be determined
Has the impact on consumers of moving from natural gas to hydrogen been considered? The cost of electrolytic hydrogen is the cost of the electricity used plus the additional costs of production and infrastructure.
At present the cost of a kWh of electricity is about three times that of a kWh of gas. The efficiency of electrolysis is about 70% and electricity will not be getting any cheaper? How are consumers expected to deal with a four- or five fold increase in their energy costs?
There is really no answer to this. However, if I’d got the question in I’d have expected some renewables enthusiast to trot out the claim that wind is now the cheapest form of generation, a claim which Gordon Hughes’ analysis of developers’ and operator’s accounts has debunked. They might also claim that this will be surplus electricity which would otherwise be not be used and so will be cheaper. Unfortunately the distorted electricity market at present doesn’t work like that. When wind generation is not required or cannot be handled, the turbines are turned off, operators are paid anyway for the electricity not generated and receive a ‘constraint payment’ which usually exceeds the subsidy they would otherwise have obtained. I do not see them agreeing to sell electricity cheaply instead.