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How To Handle 40 GW Offshore Wind (Or Not!)–Drax

January 9, 2021

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Guest Post By Joe Public

 

 

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https://reports.electricinsights.co.uk/wp-content/uploads/2020/11/201126_Drax_20Q3_005-1.pdf 

 

Drax’s latest Quarterly Bulletin has a section on storing excess wind power:

 

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I have picked out these particular claims for observation:

 

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1. Why no mention of those electricity storage systems’ capacity and discharge rates? Britain’s 4x pumped hydro stations have a total storage capacity of 26.7 GWh and discharge rate of 2.86GW.

http://www.withouthotair.com/c26/page_191.shtml

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2. “…28 TWh of storage … comparable to the total natural gas storage the UK has in the form of underground salt caverns.”

2.1 Not quite correct. It is comparable to the total natural gas storage Gt Britain has in the form of underground salt caverns plus LNG storage facilities. We have ~18,000GWh of conventional storage plus ~13,000GWh of LNG storage.

https://mip-prd-web.azurewebsites.net/DailySummaryReport

2.2 The Gross Calorific Value of hydrogen is just 3.3kWh/m^3 vs approx 11.1kWh/m^3 for Nat Gas, so low energy-density H2 has less than 30% the energy content of Nat Gas per unit volume at STP.

Consequently our energy storage capacity for hydrogen is not 28TWh, but just 8.4TWh at the same pressures.

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3. “….Perhaps some of these wind farms should produce something other than electricity. Electrolysers can be used to turn electricity and water into hydrogen. The excess electricity production in 2030 could be used to make 670 million kg of hydrogen. That would be enough to fill 133 million fuel tanks in fuel cell vehicles such as the Toyota Mirai, or to heat nearly 2 million homes.”

3.1 It’s disappointing to see the deliberate obfuscation caused by mixing units – (the weight of hydrogen produced) denying readers the opportunity to easily compare relative figures. Why did the report’s authors not continue to use electricity-industry units of TWh/GWh they’ve already used in their article?

1 kg of hydrogen contains 33.33 kWh of usable energy.

http://www.h2data.de

3.2  The “37 TWh of excess electricity” production in 2030 could be used to make 670 million kg of hydrogen.”

So the “37 TWh of excess electricity” produces 670,000,000 kg hydrogen. But that mass of hydrogen has only 22.3 TWh of usable energy. i.e. it takes 66% more electrical energy input to make one unit of energy available via hydrogen output.

3.3 We’re told “…. (670,000 tonnes of H2) would be enough to fill 133 million fuel tanks in fuel cell vehicles…”

No mention is made of the energy needed to compress low energy-density H2 into those 133 million fuel tanks.

Approx 4kWh of energy would needed to compress 1 kg (33.3kWh) of H2 to 700bar.

https://www.hydrogen.energy.gov/pdfs/9013_energy_requirements_for_hydrogen_gas_compression.pdf

This means (4/33.3) 12% of the available “37 TWh of excess electricity” is needed simply to compress the H2 into those 133 million fuel tanks. That then means that just 33TWh available to produce the H2, so only (22.3 TWh x 88% =) 19.6TWh of useable H2 is available when stored at 700bar.

Consequently, 37TWh of initial electrical energy input results in just 19.6TWh of hydrogen being available at the input of the vehicles’ fuel cells.

1.89 units of energy input to obtain 1 unit of energy into the fuel cell.

The fuel cell is then only 40% – 60% electrically efficient. This means end-to-end process efficiency requires approx 3.78 units of energy input to obtain 1 unit of energy OUTPUT from the fuel cell.

https://www.energy.gov/sites/prod/files/2015/11/f27/fcto_fuel_cells_fact_sheet.pdf

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4. The authors consider “Hydrogen could potentially be hauled to shore at lower cost, piggy backing off the existing oil and gas pipelines, which will see limited use as the North Sea fields start to wind down.” yet don’t explain what they consider to be ‘piggy-backing’.

4.1 Do they consider it to be feasible to inject hydrogen into an operational oil pipeline? Do they realise that natural gas imports have to comply with National Grid’s strict quality-control standards that hydrogen doesn’t meet?

https://www.nationalgrid.com/uk/gas-transmission/data-and-operations/quality

4.2 Regarding steel pipelines – both those to be ‘piggy-backed’ undersea, and on land – the authors might not be aware of hydrogen’s chemical effect:

“Conversion of the UK gas system to transport hydrogen” explains:

“At ambient temperature and pressures below 100 bar, the principal integrity concern for high-strength steel is hydrogen embrittlement. Hydrogen will diffuse into any surface flaws that occur due to material defects, construction defects or corrosion, resulting in a loss of ductility, increased crack growth or initiation of new cracks. These will ultimately lead to material failure. Higher pressures are thought to increase the likelihood of material failure although no threshold value has been defined independently of other factors …”

https://www.sciencedirect.com/science/article/pii/S0360319913006800


 

 Paul’s Additional Comments.

  • Their calculation that we need 1000 times more storage than we currently have sums up why storage can never be the answer to long term intermittency ( as opposed to intra-day needs), particularly since pumped storage accounts for about 95% of current storage, something which cannot be easily increased.
  • These projections are based on 40 GW of offshore wind, so the problem of surpluses will become much more acute as more wind capacity is added later.
  • The surplus wind power, 37 TWh, equates to about a quarter of total wind power. If this excess had to be thrown away, it would effectively increase the costs of wind power by a third.
  • As Joe rightly points out, the capacity of salt caverns is not 28 TWh, as far as hydrogen is concerned. It is less than 8 TWh, meaning that most of the surplus cannot electricity cannot converted to hydrogen and stored.
  • Claims of enough hydrogen to fill 133m fuel tanks, would imply maybe 3 million hydrogen cars. In reality, there are unlikely to be more than a few thousand on the road in 2030, and little prospect of many more in 2050. There may be a market for fuel cells in lorries and buses, but that will in all likelihood be decades away. (Apart from anything else, where will cars and lorries get their hydrogen from in winter, when there is no surplus wind power?)
  • It is good to see they confirm that when wind power is in surplus here, it will also be on the continent, and equally so when wind power is low.

But I’ll leave the final comment to Drax!

 

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62 Comments
  1. Devoncamel permalink
    January 9, 2021 7:44 pm

    Yet more evidence, it it were needed, that current technology doesn’t allow renewables to meet our energy needs. The rush to eradicate fossil fuels is ironically, unsustainable.

  2. It doesn't add up... permalink
    January 9, 2021 7:50 pm

    I posted this on the power shortage thread:

    Yesterday the system buy price reached £4,000/MWh for a whole hour. The problems continue. Wind dipped below 1.2GW, and coal was again running at over 3GW. An early price spike in SP 35 (17:00-17:30) of £2,750/MWh was eclipsed by the later one for SP39/40 (19:00-20:00).

    The reason for the later spike is clear: at 9.35GWh the equivalent of more than the entire energy storage at Dinorwig (9.1GWh, of which a certain amount is supposed to be kept in reserve for black start operations) was used up in pumped hydro production earlier in the day, which plummeted during SP 39, while at the same time imports from Ireland via Moyle and E-W reduced to zero as Ireland became short itself, forcing use of STOR and OCGT unusually late into the evening. And still they pretend they can get away with tiny quantities of storage in a renewables world.

    • Joe Public permalink
      January 9, 2021 11:31 pm

      “Yesterday the system buy price reached £4,000/MWh for a whole hour.”

      Back in the not too distant past – just 3 months ago to the day – this was newsworthy:

      “System prices hit £540/MWh and intraday prices peaked at £753/MWh last month”

      https://www.smartestenergy.com/en_gb/info-hub/blog/system-prices-hit-540mwh-and-intraday-prices-peaked-at-753mwh-last-month/

    • GeoffB permalink
      January 10, 2021 10:18 am

      On the 8th I noticed there was a sharp drop of available power at 0815 about 1GW and the frequency dropped to 48.8 Hz. That is rather close to tripping level!!!! Luckily as wind was low, over 3 GW of coal was running as well as Drax at 3GW and nuclear at 6 GW so some spinning mass to reduce the rate of change of frequency. I tried looking through BM reports to find out what happened, but no luck.

      • It doesn't add up... permalink
        January 10, 2021 4:15 pm

        I can’t find that in the 15 second frequency data. The lowest frequency I see on the 8th is just after 10 p.m. when it fell to 49.75Hz. I think you saw a data glitch, not a real one.

    • Micky R permalink
      January 10, 2021 2:11 pm

      Drax’s comments re pumped storage are indeed misleading. A pumped storage solution to intermittency is possible; back of the envelope calcs suggest this would involve hollowing out most the Lake District.

      The closure of the Rough gas storage facility a couple of years ago cut UK gas storage capability from about 15 days down to 4 – 5 days (winter consumption).

  3. January 9, 2021 8:00 pm

    All these types of publication like to confuse readers by mixing units. Good luck getting anybody in government to understand that vast amounts of offshore wind, as mandated by Boris’ green boss, is a recipe for disaster.

  4. A man of no rank permalink
    January 9, 2021 8:14 pm

    The Hydrogen economy is taking up a lot of thought, i.e. costing us a lot of tax payer money. Joe and Paul are right to expose the many errors, flaws and dangers.
    BUT, as we keep repeating, the Water Vapour produced by combusting hydrogen, is a greenhouse gas.
    So can I conclude that our leaders have assumed that greenhouse gases do not influence Climate?

    • dave permalink
      January 10, 2021 11:01 am

      Water Vapour is, indeed, the greenhouse gas par excellence. However, one has to work out the dynamic balances of Nature and then consider the rates involved.

      The world ocean is a ubiquitous ‘sink,’ which absorbs any ‘excess’ water vapour placed in the air. The time scale is mere days. The ocean is also a sink for carbon dioxide, but the situation is different.

      To be precise, only half of ‘excess’ carbon dioxide is absorbed into the water quickly (within a year). Because the sea is stratified it takes a long time for the absorbed carbon dioxide to mix downwards, to vacate the upper layers, and thus allow for the other half to be absorbed in its turn. By ‘a long time,’ is meant somewhere between fifty and five hundred years.

  5. It doesn't add up... permalink
    January 9, 2021 9:10 pm

    This is I think the first time I have seen a public energy company come up with a half reasonable estimate of the storage that might be needed. It’s at least in the ballpark of estimates I have made, rather than the few hundred GWh that the CCC thinks we can get away with. The trouble is of course that they are only considering current demand levels and patterns, and not a 2050 zero carbon energy system, which would make things considerably worse, especially if electricity is supposed to provide heating through weather such as we have had recently, with cold temperatures and low winds for days on end. On cold days, UK gas demand can exceed 4TWh currently – it was 4.4TWh on the 8th, albeit that a good chunk (0.92TWh) went to CCGT and OCGT. Electricity demand was about 1.25TWh overall.

    They do make the point about correlation of weather across Europe, which is often buried amid claims that it must be windy somewhere. The anti-correlation and resource required simply does not exist, as this chart shows:

    https://datawrapper.dwcdn.net/tn541/1/

    Or you can look at actual historical output across some 20 European countries in this one:

    https://datawrapper.dwcdn.net/QcA5c/1/

    I have also looked at the hydrogen issue, and my work reinforces the Drax last word:

    https://datawrapper.dwcdn.net/jpImX/2/

    If we say that the minimum acceptable load factor on hydrolysis plant is 20%, the the chart shows that for tripled (Factor 3 blue line) wind installation (about 66GW total), you can install a maximum of about 4GW of electrolysis capacity. The highest plant utilisation would be about 25%, because there would be no wind surplus available 75% of the time. You are still left with extensive curtailment and wastage, because it is uneconomic to install extra capacity for the rarer occasions when the wind surplus is larger – so you may be throwing away up to 18GW of wind production because it is not economic to install capacity that will barely be used. So hydrogen production doesn’t manage to use more than a portion of the wind “surplus” – that only exists because you invest in capacity to produce it – it is not free. So you get about 0.9GW of hydrogen, or under 8TWh a year at the plant offtake. Or we could buy 8 LNG cargoes.

    • Joe Public permalink
      January 9, 2021 11:22 pm

      “On cold days, UK gas demand can exceed 4TWh currently – it was 4.4TWh on the 8th ….”

      And with the system’s temperature forecasts, gas prices reflect that – Nat Grid’s Gas “Daily Summary Report” today showing prices up to 7th Jan:

    • Nordisch geo-climber permalink
      January 10, 2021 10:45 am

      Excellent contribution thanks.

    • Sobaken permalink
      January 12, 2021 8:46 am

      “only considering current demand levels and patterns”
      Is there any data on daily gas consumption available somewhere perhaps? BEIS gives out quarterly numbers, but that isn’t really enough to model electricity demand for heating and/or required hydrogen storage.

  6. saveenergy permalink
    January 9, 2021 9:11 pm

    Thanks Paul, a nice simple take-down… but useless against the green mentality.
    Why bring logic & fact to a woke belief fight…it makes you a looser.
    But I will try putting those figs in front of my MP & not hold my breath.

  7. Robert Christopher permalink
    January 9, 2021 9:43 pm

    It looks like it all going swimmingly well. The sooner the penny drops, the more likely we will be able to keep our gas boilers, fires and cookers.

    In Northern China, where coal is very scarce, probably due to political issues causing the reduction of coal imports from Australia, people are ‘discouraged’ from burning coal. Offenders have their coal fires filled with concrete!

    If anyone uses GWhr, especially if mixed with capacity measured in GW, I always suspect that the authors wish to muddy the waters.

  8. Chilli permalink
    January 9, 2021 9:49 pm

    Wondering if this discussion is academic since the coming massive economic depression caused by Boris’ lockdowns is sure to change the calculus on plans to vastly increase energy costs. People might not have realised it yet since the economy is still running on fumes and furlough – but once the SHTF things can change fast. Recall how the political consensus changed when Ed Miliband broke ranks by promising an energy price freeze – causing other parties to rapidly follow suit. There are two general elections between now and 2030…

    • It doesn't add up... permalink
      January 10, 2021 12:42 am

      Miliband got his timing spectacularly wrong. The next two years were a continuous bear market in energy prices. Many consumers ended up paying far more than they should have done because they were encouraged to take out fixed price deals, and energy retailers hedged to provide them. Banks made a fortune out of providing the price insurance.

    • Gerry, England permalink
      January 10, 2021 12:47 pm

      To which you can add the ever growing effects of leaving the largest trade agreement in the world. The advice across the Single Market is don’t buy anything from the UK unless you can help it. Everything from the UK will come with an increased cost so over time additional sources will take over from the UK and our exports will drop. This is not a result of Brexit but of the botched Tory version of Brexit for which those Remainers who focused all their efforts on trying to overturn the vote instead of putting forward a better plan share the blame.

      • January 10, 2021 1:07 pm

        It’s always puzzled me why Remainers threw out this option

        Of course, they would say it meant following all the EU rules, without any say in making them.

      • Ben Vorlich permalink
        January 10, 2021 4:42 pm

        By better plan I assume you mean WTO, or as Boris had it Australia type deal? Which raises the question if the WTO option is so good why has Australia been negotiating a trade deal with the EU since 2018? Doesn’t a WTO arrangement involve customs checks, tariffs and documentation? I wonder if a WTO arrangement would have protected the fishing industry from being sacrificed to keep the interconnectors open

        I’m no expert so clarification and enlightenment would be helpful.

  9. Paul H permalink
    January 9, 2021 10:31 pm

    Incredible comments and calculations on the article, but they count for naught. There is an agenda afoot and the people orchestrating it, of whom we know nothing, will never be held accountable when disaster strikes. The current crop of politicos who are the face of ‘The Project’ will be long gone and an as yet unknown sap will be put in place to take the rap. The Millibands, Hunes, Daveys, Boris will have long gone and be enjoying their rewards. Does anyone have any opinions regarding the Maunder Minimum which according to some, is fast approaching, and if the climate does go in that direction of a mini ice age, with the turn-off of fossil fuels, we really are in deep trouble.

    • Graeme No.3 permalink
      January 10, 2021 4:17 am

      Paul H:
      The Maunder Minimum had substantial volcanic activity around 1600-1620 (not a lot known about it).
      My question is WHEN was the Maunder Minimum? Like a lot of things in The Settled Science the dates seem vary, with 1660 to 1710 put forward most often. 1709/10 winter was ‘the big freeze’ but summers in England 1660 (according to Pepys), 1665 and 1666 were quite warm. Also (from memory) 1645 was a very cold year in France.
      Perhaps you could organise a vote?

      • Graeme No.3 permalink
        January 10, 2021 11:01 am

        Did a little checking as I should have done first.
        1607/8 the ‘Great winter’ 2,000 drowned in the Severn estuary (flooding in
        East Angla)
        1614/15 heavy snow in winter in Yorkshire & Derbyshire.
        1616 Hot dry weather in summer.
        Sept. Houses flooded in Leeds after 38 hours continuous rain.
        1620/21 Frost fair held on the Thames. A severe winter over western Europe
        1622 Scotland in particular, the harvest was stated to be ‘catastrophic’.
        Reports blame poor weather due to excessive rainfall
        1626 Dry, hot summer (London/South).
        1632 Autumn a notably wet period, ending with a frost
        1634/5 Severe winter; Thames frozen
        1640 This year was WET with frequent flooding. At Tewkesbury there were at least eight floods between (24th June) and (29th September).
        1643/44 Hot summer (London / South). in January 1644: 8-day snowfall 31st January to 7th February
        1645 Hot / dry summer
        1648/49 Great frost; Thames frozen.
        1658 Swedish army marches across the frozen Baltic into Denmark

        Notice how stable the British climate was when the CO2 level was low.

      • Paul H permalink
        January 10, 2021 12:41 pm

        Graeme No.3. Many thanks for those elucidations, very interesting. Your last point has me wondering ‘Notice how stable the British climate was when the CO2 level was low.’ How is that known, or has that gone over my head? Thanks again, Paul H

  10. Mack permalink
    January 9, 2021 11:18 pm

    O/T Paul, but with American Big Tech ramping up furiously to censor discordant voices in the political debate, how long before a Biden presidency and his supporters around the world squash all dissenting voices in the climate debate so as to maintain the alarmist narrative? Anthony Watts has already flagged up his potential worries and HMG seem fully signed up to the ‘Democrat’ histrionics. I hope you have a Plan B should the wave of censorship emanating from the US hit these shores so that you can still broadcast your regular epistles of sanity and common sense. Troubling times indeed.

    • El Toro permalink
      January 10, 2021 10:54 am

      Yes, Mack, with Common Purpose, wokeness and cancellation already underway here, the seeds are sown. Add to that, the calls for censorship of anti-vaxers and surely climate scepticism can’t be far behind? It’s a pity that Trump wasted his opportunity.

    • Dave Ward permalink
      January 10, 2021 1:52 pm

      “Anthony Watts has already flagged up his potential worries”

      So has Pierre Gosselin:

      https://notrickszone.com/2021/01/09/power-supply-fiasco-green-energy-blackout-hits-germany-fossil-fuels-to-the-rescue/#comments

      Pierre says: “Clearly they’re convinced they can get away with anything”

      The cancelling of Trumps email account can be added to the list. At this rate it won’t be long before the Domain name registry services will be “Got At” – making it almost impossible to move to a new hosting provider, even to those prepared to take the risk…

  11. Gamecock permalink
    January 9, 2021 11:56 pm

    ‘The bumpy ride shown in these charts is the daily average of demand and output – the hourly variation is even stronger, but this could more easily be accommodated by battery storage, pumped hydro and electric vehicles.’

    And electric vehicles. Hmmm.

    • StephenP permalink
      January 10, 2021 10:01 am

      I can see problems with all the suggested solutions:
      How would people react to having mega-batteries on their doorstep, next to where the electricity is going to be used?
      Where are the pumped storage reservoirs going to be placed? The fuss over the location of a single new reservoir has to be seen to be believed. (Remember Meldon reservoir on Dartmoor.)
      If EV batteries are going to be used as a buffer to make up the shortfall, it effectively removes our right to travel when want or need to and puts us at the whim of the electricity big brothers.
      I would be interested to know how the past couple of weeks in the UK would have panned out in this vision of the future. I get the problems would be dismissed with a wave of the hand as being a minor detail. There certainly would have been little surplus electricity to recharge the buffer stocks.
      Lastly I feel sorry for the people in the control room who have to manage the scenario. It would be like the jugglers who have to keep 12 plates spinning on sticks, with the added complication of different pricing for each source. The present system does not allow the most economical mix, since the solar and wind have first turn.

      • January 10, 2021 11:40 am

        If EV batteries are to be used to buffer the grid, folks will just unplug their cars when they are brimmed. Of course games could ensue in order to make that more difficult.

        Either way, the pinch point is likely to be out of synch. If the demand maxes out at about 6, people won’t plug their cars in until 8. And so the games will continue.

  12. Gamecock permalink
    January 10, 2021 12:00 am

    ‘The Saudi Arabia of wind power?’

    Saudi Arabia restricted supply to jack up prices. Perhaps one should aspire to be someone else.

  13. Martin Thomson permalink
    January 10, 2021 9:52 am

    Sorry to be a pedant, but can we stop confusing hydrolysis and electrolysis – they are not the same thing.

  14. Coeur de Lion permalink
    January 10, 2021 10:31 am

    Have I missed something or will my car have a fuel tank of hydrogen under pressure? Quick, get up the embankment and over it before the hindenburg.

    • January 10, 2021 11:43 am

    • Joe Public permalink
      January 10, 2021 1:50 pm

      A vehicle fuel tank full of hydrogen at 700bar/10,000psi is likely safer than a fuel tank full of petrol / diesel.

      In an accident, the former likely vents to atmosphere, the latter’s highly inflammable liquid pools under the vehicle where it can ignite and conflagrate after coming into contact with hot exhaust or brakes.

      • Dave Ward permalink
        January 10, 2021 2:04 pm

        @Joe – you’re assuming the “Venting” is in some way controlled. If a 700bar tank fails catastrophically the venting of hydrogen is going to be a minor consideration. 700bar/10,000psi means a force of about 4 TONS is being exerted on an area the size of a large coin! Look at some of the videos of everyday bottled gas cylinders exploding. Shrapnel can fly for hundreds of feet, and that’s at not much more than 20bar, or so which these cylinders are usually tested to.

        Admittedly, it’s unlikely that any members of Dads Army would be able to stick a bayonet through a hydrogen tank – I enjoyed watching the original feature length film which was on the telly recently!

    • Coeur de Lion permalink
      January 10, 2021 2:21 pm

      Further to. I hadn’t realised the height of the pressure in this fuel tank . What does such a tank cost or weigh? How sound are the reducer and pipe connections? I’ll stick to my AdBlu diesel Citroen and its £20 per year road tax, thanks.

      • Joe Public permalink
        January 10, 2021 5:32 pm

        @ Dave Ward January 10, 2021 2:04 pm

        O ye of little faith.

        Perhaps you’ll be reassured to know that whilst the Gas Safety Regs will not allow compression fittings on (natural) gas pipework operating at 21mbar, HSE in its infinite wisdom in “Installation permitting guidance for hydrogen and fuel cell stationary applications: UK version” decrees merely “Compression joints are generally not recommended for use on (high pressure) hydrogen systems” 😀

      • Gas Geezer permalink
        January 10, 2021 10:05 pm

        “Compression joints may be used on gas provided they are in an accessible position . This precludes their use under floorboards , in ducts and behind boxing” . Taken from my Logic Certification domestic gas safety training manual.

  15. Gerry, England permalink
    January 10, 2021 12:50 pm

    I noticed in an article on car sales in the Mail yesterday while bigging up the sales of battery cars it studiously avoided any mention of the big drop in overall car sales.

    • January 10, 2021 3:31 pm

      People are just waiting for hydrogen Toyota Mirais to cost a bit less than 70 grand 😆

  16. Stuart Brown permalink
    January 10, 2021 2:10 pm

    Clearly we need more clean, green despatch-able energy – and here it comes! A little bit anyway:
    https://theenergyst.com/first-ppa-to-be-signed-in-the-uk-for-geothermal-electricity/

    All of 3MW, and good luck to them, but it’s the last sentence that does it for me:
    “In addition to power generated at the site, plans have been submitted for a geothermally heated biome, that will be used to mature and then distil sustainable rum.”

    Now there’s a carbon capture scheme Drax/Boris should be looking at – using the CO2 rich warm exhaust to make Yorkshire the Barbados of – er – rhubarb rum? Did anyone else figure that rum production was a feared ‘carbon’ intensive process that needed sustainability research?

  17. cajwbroomhill permalink
    January 10, 2021 2:52 pm

    All the debates about “Green” alternatives to fossil fuels are wasteful deceptions and distractions to the obvious truism that no empirical, as opposed to theoretical, evidence co demns the benefits fossil fuels offer thus necessitating their costly, own-goal replacement.

  18. Jordan permalink
    January 10, 2021 4:26 pm

    My first comment here. Slightly long comment (sorry for that, but I hope you’ll find it interesting).

    One of the things sorely missing from debate is the cost of decarbonisation. The Drax article does the same – floating ideas without consideration of cost.

    The absurdity of a net-zero target for CO2 emissions does the same thing. It assumes every last human emission of CO2 is still worth abating, whereas government policy should be supported by a cost-benefit analysis.

    When abatement costs are very low and emissions are high, it might be possible to make a case for some abatement. But, as emissions reduce, the case for further abatement will diminish – for example, if the UK was down to the last couple of million tonnes of CO2, what would be the benefit of reducing further? Against this, there is a rising marginal cost for abatement – more expensive options are turned to as the lowest cost options reach their full potential.

    Net zero is absurd because it fails to recognise the above. The very last emissions could be exceedingly expensive to abate, but a net zero target seems to overlook this.

    So the question arises: at what cost of CO2 abatement does the UK reach a point that further CO2 abatement is unjustified?

    At the moment, the UK has the EUETS price and the UK carbon tax to set a value on emissions. I understand the combined cost is about £40/te CO2. This is today’s marginal cost of abatement, and any options to reduce emissions at below £40/te should be justifiable against this price. Higher cost abatement options would not be expected as there is the lower cost option of just suffering the £40/te.

    What about building excess wind capacity and storing excess production as H2? The above article provides some useful parameters to get to a rough guess on its cost as an abatement option. The following is quite broad-brush, so please make allowances. However, if there are any obvious errors then feel free to respond with corrections.

    Lets say the cost of new wind production is £50.00/MWhe. Roughly speaking, the last CfD price, and it is considered to be competitive (another debate).

    The comment above says that it takes 66% more electricity to produce “useful” energy stored as H2. So divide the above £50/MWh by 33% = £151.52/MWhh. By “useful H2”, I assume this means lower heating value.

    Another comment above suggests it takes about 12% of the energy to raise to storage pressures, therefor increase the cost by 12% to get £169.70/ MWhh (compressed).

    If we are talking about storing H2 to manage power demand, the stored H2 (LHV) is then use to produce power in a modern CCGT power station with 60% LHV thermal efficiency. Therefore divide the previous figure by 60% to arrive at £282.83/MWhe.

    The last figure above may be considered to be the cost of (cough!) “clean power” via the above route. As an abatement option, the question we are interested in is the cost per tonne CO2.

    The difference between the competitive £50/MWhe and the £282/MWhe when retiurned to the power market through H2 storage is £232.83/MWhe.

    Consider this to be the cost of saving circa 350g/kWh for an unabated CCGT (the unabated opportunity cost). We can therefore calculate the cost of abatement as: £232.83/MWhe divided by 0.35te/MWhe savings in CO2 = £665.22/te CO2 abatement cost.

    As a potential policy option, the questions are then whether £665/tonne is value for money? Or:
    can UK policy justify a cost of over £650/tonne to abate CO2 compared to other priorities for society?
    Is there a lower cost alternative which should be favoured before we even think about the above?
    Is the benefit of CO2 abatement worth more or les than the above figure?

    • It doesn't add up... permalink
      January 10, 2021 7:26 pm

      I discovered a rather alarming feature about the way the government calculates the value of emissions savings. In fact, it has been this way since 2009. From the Executive Summary:

      The previous approach used within Government to carbon valuation in policy appraisal, called the Shadow Price of Carbon, is based on estimates of the lifetime damage costs associated with greenhouse gas emissions drawn from the Stern Review (known as the Social Cost of Carbon, or SCC).
      This paper sets out a revised approach to valuing carbon in policy appraisal, following a review undertaken within Government in the course of 2008 and early 2009. It concludes that the approach, based on estimates of the SCC, should be replaced with a target-consistent approach, based on estimates of the abatement costs that will need to be incurred to meet specific emissions reduction targets. The case for change is motivated by the considerable uncertainty that exists surrounding estimates of the SCC. The change will have the effect of helping to ensure that the policies the UK Government develops are consistent with the emissions reductions targets that the UK has adopted through carbon budgets and also at an EU and UN level.

      In other words, the cost of carbon is whatever it takes to achieve the target emissions level – even if it is £1 million per picogram.

      Click to access 1_20090715105804_e____carbonvaluationinukpolicyappraisal.pdf

      • Jordan permalink
        January 10, 2021 11:44 pm

        Thanks for your comment. The idea of a shadow price is sound, although the extract you cite is typical of proponents of net zero who quietly slip past the thorny question of cost.
        Which isn’t really playing the game as UK law and regulation should be accompanied by a cost benefit analysis.
        When Drax (and others) come forward with bright ideas about decarbonisation, discussion of the cost per CO2 abated is quite a useful way to assess the chances of it ever happening.
        I read somewhere that UK CO2 emissions are about 5 tonne per capita per year. If £40/tonne (EUETS+UKCPS) is cost of abatement, we could get the impression that the long-term cost of net zero is £200/yr per head of population. I take no position on whether that would be acceptable to the average Brit.
        But I venture the above £40/te is nowhere near the true marginal cost of abatement needed to get all the way to net zero. The UK would be faced with ever more expensive abatement measures as it travelled the road to net zero.
        In the example above, I suggest the cost of wind->H2storage->electricity is £650/te CO2 abated, using unabated CCGT as the benchmark. (The cost estimate doesn’t include the cost of capital for H2 manufacturing and storage equipment, so the true cost will be a good bit higher.)
        For this to be the most economic alternative of abatement in the UK, the marginal cost of CO2 abatement will need to exceed this figure. If so, an average Brit’s 5 tonne per annum CO2 would cost at least 5*650 = £3250/yr to abate. That’s going to be hard to explain in terms of what the average Brit is getting for their hard earned cash. There are very many good things the UK can be doing for that kind of money – is reducing CO2 really the best?
        It suggests a wind->H2->power scheme is either a very long way into the future (the can will be kicked down a very long road), or it will never happen (pie in the sky). I will start the bidding at pie in the sky.

      • It doesn't add up... permalink
        January 11, 2021 2:25 am

        If you want to get scared, try looking at the values estimated by BEIS in Table 3 here:

        https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/793632/data-tables-1-19.xlsx

        They don’t make your estimation process far out of line.

        Incidentally, I think the UK carbon floor price stands on its own – there is a top-up charge of the difference between the EU ETS price and the floor price when it is lower. But the scenarios elsewhere show some dramatic increases are expected. Trebling energy costs by 2050, or at least 2.5 times higher, at wholesale features in the National Grid 2020 Future Energy Scenarios. No wonder they are also projecting energy demand falling from about 1400Wh in 2019 to 600TWh in 2050. You could think of it as a return to the three day week.

  19. MikeHig permalink
    January 10, 2021 4:36 pm

    Thanks to Joe and Paul for this excellent analysis.

    I think the storage possibilities for hydrogen are even less than Joe calculated:
    <>

    I very much doubt it would be practical, let alone economic, to replace the 13,000 GWh of LNG storage with liquid hydrogen. Thus only the gaseous storage could be used. So the energy storage capacity for hydrogen drops to about 5.4 TWh, less than 20% of the gas figure.

    • MikeHig permalink
      January 10, 2021 4:38 pm

      Apologies, I managed to do some inadvertent editing.
      The full post should be:

      Thanks to Joe and Paul for this excellent analysis.

      I think the storage possibilities for hydrogen are even less than Joe calculated:
      “2.1 Not quite correct. It is comparable to the total natural gas storage Gt Britain has in the form of underground salt caverns plus LNG storage facilities. We have ~18,000GWh of conventional storage plus ~13,000GWh of LNG storage.
      2.2 The Gross Calorific Value of hydrogen is just 3.3kWh/m^3 vs approx 11.1kWh/m^3 for Nat Gas, so low energy-density H2 has less than 30% the energy content of Nat Gas per unit volume at STP.
      Consequently our energy storage capacity for hydrogen is not 28TWh, but just 8.4TWh at the same pressures.”

      I very much doubt it would be practical, let alone economic, to replace the 13,000 GWh of LNG storage with liquid hydrogen. Thus only the gaseous storage could be used. So the energy storage capacity for hydrogen drops to about 5.4 TWh, less than 20% of the gas figure.

      • It doesn't add up... permalink
        January 10, 2021 7:50 pm

        The density of hydrogen at 700bar is 42kg/m^3, as against 71 kg/m^3 as a liquid. But the cryogenic LNG tanks aren’t designed for ~20Kelvin – more like 110K – or for 700 bar – more like <20bar.

        https://energies.airliquide.com/resources-planet-hydrogen/how-hydrogen-stored

        Cavern storage in any case is probably limited to below 200bar, so that will reduce the density to 12kg/m^3. Of course, methane will be similarly limited. Some useful insight into some of the considerations for salt cavern storage hinted at here:

        https://www.sciencedirect.com/topics/engineering/salt-cavern

      • Joe Public permalink
        January 10, 2021 9:43 pm

        Hi Mike, I wouldn’t disagree with your conclusion.

        LNG is stored at a temperature of approx -162°C, whereas liquid hydrogen requires cooling further, to about -253°C.

      • MikeHig permalink
        January 11, 2021 12:34 am

        Idau: bulk LNG tanks are usually low pressure, not much above atmospheric.

        Aside from the practical challenges of handling and storing liquid hydrogen, there is the huge energy requirement to liquefy it in the first place. It takes about 12 kWh per kg which is equivalent to approx one third of the energy content of the hydrogen.
        Add the energy to keep it cold and that required for re-vapourisation and the round-trip losses probably add to something like 50%!

      • Joe Public permalink
        January 11, 2021 2:23 pm

        IDAU

        “Cavern storage in any case is probably limited to below 200bar …”

        Britain’s largest gas storage facility is Stublach. Its site says it can store 450 million cubic metres of gas (at STP) in its 20 caverns totalling 10.18 million cubic metres.

        https://www.storengy.co.uk/storengy-uk-stublach-site/learn-more-about-gas-storage

        Ignoring temperature change, that would indicate a storage pressure of approx 44bar.

      • It doesn't add up... permalink
        January 11, 2021 4:33 pm

        Here are specific plans for hydrogen storage at Stublach

        The Phase 1 feasibility study concludes that a cavern could be created at the proposed location with a minimum volume of 300,000m3. With a range between 300,000m3 to 350,000m3. This minimum volume would correspond to a total storage capability for hydrogen of approximately 1850 tonnes; with correspondingly more hydrogen for a cavern at the upper end of the range. The storage cavern would be normally operated by cycling the pressure between a minimum pressure and a maximum pressure. The maximum pressure is determined by the geology and depth of cavern to ensure the pressure containment is not compromised. The minimum pressure is likewise determined to ensure the integrity of the cavern is not stressed. The working gas volume is the quantity of hydrogen that can be injected and withdrawn from the cavern between the minimum and maximum pressures. This value will be set accurately at the end of solution mining when the exact free volume of the cavern is determined by survey. The initial estimate for working gas volume between the minimum pressure of 30bar and the maximum pressure of 80bar is approximately 1,100 tonnes of hydrogen.

        Click to access Phase_1_-_Inovyn_-_HySecure.pdf

        From what I have found it seems the methane storage maximum is 100 bar. From a summary of the project:

        The proposed gas storage project will store natural gas in 28 underground salt cavities specifically designed for this purpose. The cavities will be situated approximately 500m (~1700ft) underground and the gas will be stored at pressures up to 100 barg.

        Click to access 20080654_nts2_en.pdf

      • It doesn't add up... permalink
        January 11, 2021 4:46 pm

        I suspect Stublach are quoting the working volume of gas, excluding the cushion gas. The 30-80 bar operational range is perhaps the more relevant one.

      • Joe Public permalink
        January 11, 2021 6:17 pm

        Thanks IDAU

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