Skip to content

Can Grid-Scale Storage Solve The Intermittency Problem?

February 7, 2019

By Paul Homewood

GWPF have published a new paper by Jack Ponton, Professor of Engineering at the University of Edinburgh, on whether storage systems can solve the intermittency problem of renewable energy.

It considers various options, including batteries, pumped storage and hydrogen:



A new briefing paper from the Global Warming Policy Foundation (GWPF) dismisses the idea that grid-scale electricity storage can help bring about a UK renewables revolution.
According to the paper’s author, Professor Jack Ponton, an emeritus professor of engineering from the University of Edinburgh, current approaches are either technically inadequate or commercially unviable.
Many commentators have suggested that intermittent power from wind turbines could simply be balanced with batteries or pumped hydro storage, but as Professor Ponton explains, this approach is unlikely to be viable.
“You need storage to deal with lulls in wind generation that can last for several days, so the amount required would be impracticably large. And because this would only be required intermittently, its capital cost could probably never be recovered”.
Professor Ponton also thinks that another potential saviour of the renewables revolution – hydrogen storage – has been unjustifiably hyped:
“A major problem with hydrogen is its low volumetric energy density. The only practical way of storing the large volumes required would be in underground caverns or depleted gasfields. We are already short of this type of storage for winter supplies of natural gas.”
Professor Ponton concludes that a lack of suitable storage technologies means that intermittent renewables cannot replace dispatchable coal, gas and nuclear power and so a sensible energy policy cannot be based on them.
“Wind and solar power are not available on demand and there are no technologies to make them so. Refusing to face these inconvenient facts poses a serious threat to our energy security”.


 The full paper is here.

  1. Dave Ward permalink
    February 7, 2019 3:01 pm

    “You need storage to deal with lulls in wind generation that can last for several days”

    Make that “Several Months” and you might be getting there…

    • It doesn't add up... permalink
      February 7, 2019 3:28 pm

      Indeed, seasonal variations are quite crippling, unless you are prepared to throw away large amounts of energy. Inter-year variations make matters even worse – you have to guard against at least a 1 in 50 bad year. Even allowing for round trip losses in a pumped hydro system of about 25%, 100% wind and solar would require something of the order of 35TWh of storage capacity in the UK just at current levels of demand (much more with electrification of transport and heating), assuming matched net supply and demand over a period of years. Of course, over-investing on a massive scale drives up costs enormously. Where we would put 4,000 Dinorwigs is a different question altogether.

    • John F. Hultquist permalink
      February 7, 2019 4:30 pm

      That is true, see:

      wind power is the green line at the bottom

  2. February 7, 2019 3:19 pm

    I always go back and see what Chief Scientific Advisor Prof David MacKay said in his book ‘Sustainable Energy – without the hot air’ back in 2009. He was quite clear that grid-scale storage was not feasible:
    “How to ride through these very-long-timescale fluctuations? Electric vehicles and pumped storage are not going to help store the sort of quantities required”. He was quite clear that there was no solution that would work.

  3. Curious George permalink
    February 7, 2019 3:52 pm

    The grid-scale storage surely could solve the intermittency problem. Unfortunately, it does not exist. Alternatively, a cold fusion could provide us with plentiful energy. Unfortunately …

  4. Harry Passfield permalink
    February 7, 2019 4:08 pm

    As Paul has pointed out many times, one of the very best power storage facilities that can be called on at a moment’s notice is – a lump of coal.

    • John F. Hultquist permalink
      February 7, 2019 4:33 pm

      at a moment’s notice is – a lump of coal.

      At the moment it is needed, it needs to be pulverized. But we do understand.

    • February 7, 2019 4:35 pm

      It takes a bit longer than a moment to get a coal-fired power station up to speed. And a lump of uranium is much more energy-dense than a lump of coal.

      • Harry Passfield permalink
        February 7, 2019 4:38 pm

        Good point Phillip. How many new Nuclear power stations are planned? Probably the same as new coal. (sigh)

      • Gerry, England permalink
        February 8, 2019 1:50 pm

        Having worked on a steam turbine driven generator that was cooled down for us to work on, I can tell you that from cold – it was around freezing that night – it would take them 12 hours to bring it up to temperature to avoid thermal damage. Hence to reduce that time it requires heating and uses up energy doing nothing.

  5. February 7, 2019 4:42 pm

    Wind and solar power are not available on demand

    And in the case of solar, not available at all for at least half the year.

    • Curious George permalink
      February 7, 2019 5:05 pm

      Can’t you be optimistic like many true believers?

    • Joe Public permalink
      February 7, 2019 5:53 pm


      “And in the case of solar, not available at all for at least half the year.”

      In GB, not available for nearly 9/10ths of the year.

      Annual average Capacity Factor is just ~11%, and only 2% during our month of greatest demand.

  6. markl permalink
    February 7, 2019 5:09 pm

    The people clamoring for wind and solar power in the belief that it can replace fossil fuels and nuclear completely neither know what they are talking about nor understand the consequences of doing so. Unfortunately most/many people believe grid storage via batteries is viable today. Even pump storage is not reliable ….. ask New Zealand. Or hydro …. ask South America.

  7. MrGrimNasty permalink
    February 7, 2019 5:28 pm

    Coal station closure.

    • Dave Ward permalink
      February 7, 2019 6:20 pm

      That’s another 2GW which won’t be available next winter! How convenient that it’s to be closed just as peak demand is approaching…

  8. February 7, 2019 6:19 pm

    The modern trend is for wind farms to come with a battery, no further effort is required by the Snake Oil Marketing Department, as the gullible will believe that the battery solves the intermittency problem for that wind farm, and the MSM will ask no awkward questions.

    BBC R5 is currently providing full broadcast facilities for the Snake Oil Marketing Department, and R4 Inside Science for its politburo. Step back and gawp in amazement at what has happened to science and journalism.

    • It doesn't add up... permalink
      February 7, 2019 7:18 pm

      Here’s a chart of some of Musk’s Big Battery operations alongside the output of the adjoining Hornsdale windfarm (click to see larger version):

      The cumulative charge/discharge is the wavy purple line, with the greater quantity of charge than discharge over time reflecting round trip losses. It can readily be seen that the battery operations have little to nothing to do with the wind farm output: the main purpose is contributing towards stabilising the entire grid, which actually earned more revenue than price arbitrage operations (charge when prices are low, and discharge when they are high). It’s also easy to see that when wind output is low, the market is liable for price spikes (cyan line).

  9. It doesn't add up... permalink
    February 7, 2019 6:56 pm

    Having read the briefing paper through, I note that Prof Ponton actually cites some of the work of Roger Andrews for Energy Matters, who died just recently. His work lives on. Here is the reference:

  10. Adamson permalink
    February 7, 2019 7:37 pm


    Next question.

  11. Ian Miller permalink
    February 7, 2019 7:46 pm

    The problem lies with Greg Clark & Claire Perry who for all intent and purposes actually belong to the Green party and whose tune they are dancing to, Lock Stock & Barrel,
    They certainly do not belong in the Conservative Party. To any sound technical advice from engineers who can improve living standards at affordable cost, they have closed ears.

    • It doesn't add up... permalink
      February 7, 2019 11:23 pm

      I recently downloaded the UKPIA Statistics which contains a foreword by Perry that blathers about wanting the oil refining business to lead in CCUS, followed by another from the UKPIA President that includes:

      Challenges. As society changes, our industry is continually presented
      with, and rises to, new challenges. In response, our sector continues
      to make significant investments to minimise the environmental impact
      of refining and to meet changes in product specifications. Recently,
      Government has laid down several future challenges through changes
      to the Renewable Transport Fuels Obligations which sets targets for
      biofuels to 2032 including the challenge to provide a quantity of, as yet
      unknown, development fuels. It has also indicated its intent to end the
      sale of all new conventional petrol and diesel cars and vans by 2040.
      Going forward, our sector will seek to adapt to these and other, new
      challenges. But how?

      I’m not sure I would have been that polite.

  12. Gamecock permalink
    February 8, 2019 12:17 am

    “You need storage to deal with lulls in wind generation that can last for several days, so the amount required would be impracticably large. And because this would only be required intermittently, its capital cost could probably never be recovered.”

    BWTM: you would need the additional generation to charge them up, too. You need generational capacity to meet current needs, PLUS capacity to meet future needs.

    “Its capital cost could never be recovered.” FIFY

  13. Ian Miller permalink
    February 8, 2019 12:42 pm

    Nissan, a producer of efficient and clean diesel engined cars, is leaving the UK because of threatened Politically Correct Emission regulations in Europe and the UK,
    Meanwhile the rapidly rising cost of ‘renewables’ and the 2008 Climate Change Act, will make UK manufacturing uncompetoitive post Brexit .

    As head of BEIS, what planet is Greg Clark living on ??

  14. JoseDispatcher permalink
    February 11, 2019 6:16 pm

    I agree that storage is too expensive to solve the interseasonal energy transfer problem, but the Grid-Scale Storage GWPF briefing is limited in considering alternatives.
    The report Minnesota Solar Potential Analysis is good for comparison.

    This last study results indicate that Minnesota could achieve its goal of 10% solar at costs comparable to the cost of natural gas generation (2025). It also shows that the expected cost declines of solar, wind, and storage will enable Minnesota to achieve 70% solar and wind by 2050 with generation costs comparable to natural gas generation costs. There are some other important (and chocking) conclusions:
    – Additional capacity coupled with energy curtailment is considerable less expensive than, and a viable alternative to, long-term or seasonal storage in a high renewables future (curtailment between 26% and 60% in the different alternatives of 70% solar and wind generation, without conventional generation; it reduces for values between 18% and 38% using 10% of conventional generation).
    – The use of traditional and flexible generation during brief periods of low-solar and low-wind production significantly reduces the generation costs for nearly half in the 70% solar and wind scenario.
    – Short-term storage is an important part of high renewables future, because it expands the dispatch capabilities of wind and solar assets (16 to 50GWh is needed for intra-hour variability in the 70% scenario, representing roughly one to five hours of Minnesota’s average hourly load); also, shifting of key flexible loads may further decrease generation costs (new EVs and domestic residential hot water loads, etc.).

    The ARENA study can also be used for comparison and concludes that storage of dry biomass in silos is extremely cost effective (I would say that it is like keeping coal in the storage park of a power plant, another example of energy storage) and that underground storage of hydrogen is the next cheapest option. To reach a more decarbonized system by 2050 leaves time for many technology surprises, like those proposed by Eurelectric as Power-to-X…

    • February 11, 2019 10:07 pm

      Sorry if I am oversimplifying, but what you seem to be saying is that:

      High levels of renewables are viable as long as you have plenty of conventional generation waiting on standbe, and as long as you are happy to have “energy curtailment” , ie power cuts.

      Meanwhile, as you admit, storage is pretty useless as a back up for intermittency, other than for a few hours, eg stoting solar during the day for use at night.

      There is nothing unexpected here.

      But two questions:

      1) What does the Minnesota study assume about availability of power from the rest of the US grid?
      2) What happens to all of the excess power generated when there is too much wind/solar power?

      • JoseDispatcher permalink
        February 12, 2019 10:00 am

        The Minnesota study did not include integration with MISO market. Therefore, the model did not consider opportunities to export / import leading to a conservative analysis (interconnections are a competitive tool with storage and less expensive).

        In the past, wind and solar have relied on subsidies. Recently, liking it or not, some wind and solar projects have appeared that do not need a subsidy or tax break to be viable. That has changed the energy game.

        Using a CCGT as the benchmark, there is a replacement benefit by VRE – Variable Renewable Energy if the VRE LCOE is lower than the CCGT’s LCOE. As the CCGT fixed cost is low, the key point starts when VRE LCOE is lower than the CCGT variable cost (and it is necessary to respect this criteria to define a level of acceptable curtailment). Of course, the backup and integration costs problem remain and it continues being a challenge to keep the system total cost affordable.

        The Minnesota study has the advantage of making clear that: “daily” cycle storage is important and economically justifiable; curtailment might be a better alternative than invest to much in storage; keeping a reasonable level of dispatchable generation has a strong impact in reducing total system costs (the backup alternative using “yearly” cycle storage is too expensive).

Comments are closed.

%d bloggers like this: