Clean Power

Published on October 9th, 2012 | by James Ayre


German Study: Not Much Power Storage or Coal Power Needed for 40% Renewable Power Supply

October 9th, 2012 by  

There isn’t much of a need for power storage in Germany even if it increases the share of its electricity that is generated by renewable sources by around 50%, according to a new study by the German engineering association VDE.

Importantly, the study has shown that “baseload power – coal and nuclear – will have to go as the country switches to renewables.”


German engineering association VDE finds that the need for storage will be modest [up] to a 40% share of renewable power, at which point the need will increase. But the chart [above] also shows that German engineers believe that nuclear (red), brown coal (brown), and hard coal (black) are incompatible with renewable power. German engineers expect their country to mainly switch to cogeneration (fired with both biomass and fossil fuels) along with gas turbines running on natural gas and power-to-gas, a way of storing excess power seasonally.

There have been doubts expressed in the international media that Germany may not be able to switch over directly from nuclear to renewables without first relying on ramped-up coal use during the transition. But that concern isn’t a common one within Germany. As the new study shows, renewables completely ‘obliterate’ the need for baseload power.

The study’s main question was: How will intermittent wind and solar power affect the grid? And how much electricity will need to be stored?

“In five scenarios, the VDE finds that dispatchable power generators will mainly have to be flexible, but also that this requirement can be met in all of the scenarios. And up to a 40% share of renewables, the cost of power storage (or otherwise lost excess power production) remains moderate, only raising the cost of power by 10% in the worst case,” Craig Morris of Renewables International writes.

The study’s findings aren’t really a surprise. Renewables International had already found based on its calculations that Germany won’t need to make any real changes to its grid and won’t need very much power storage if it meets the targets that it currently has set for wind and solar. And we’ve reported on the lack of need for storage up to a high renewables penetration rate several times, as well.

If the targets are met, Germany will get around 40% of its electricity from renewables. As a comparison, it got around 25% of their electricity from renewable sources during the first half of 2012. So far, the effect has mostly been to offset power from natural gas, but it’s been increasingly “cutting into the baseload.” Denmark, which is already sourcing over 40% of its power from renewable sources, hasn’t had to create any major power storage infrastructure so far.

“To move beyond 40% to 80% renewable power (the target for around 2050), Germany could need as much as 14 GW of short-term and 18 GW of seasonal power storage to meet its peak power demand of around 80 GW in the moderate scenario. At that point, power prices would be roughly 10% greater than in 2011, but reaching 100% renewable power will be quite expensive indeed. The German engineers estimate that the final 20% will triple the need for power storage, raising prices once again by around 19%.”

As the chart above shows, not only will nuclear disappear (as national policy is to phase it out), but coal power use will fall off, nearly disappearing by the time the country sources 80% of its electricity from renewable sources.

“The country’s phaseout of coal power is based not on an official policy, but rather on a general understanding among experts in the power sector that the switch to renewables will gradually obliterate the need for baseload power.”

Source: Renewables International
Image Credit: VDE | Caption: Renewables International

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • Why is Clean Technica reprinting my articles from Did you get our permission to do this?

  • Very encouraging information. Our findings from modeling power systems point to the same direction: a lot of renewables can be accommodated by simply implementing more flexible dispatchable capacity.

    One comment, if I may, on the choice of wording: “baseload won’t be needed” – another way of looking at it would be to say that ‘baseload’, i.e., coal and nuclear, will not be feasible to operate in a system like this. Their capex is huge, opex low, and only way to make profit is to run 8000+ hours per year on full load. With 40+% renewables, that won’t happen, so traditional baseload will become prohibitively expensive and thus price itself out of the market. Again, fast flexible capacity is needed to balance the system, and coal and nuclear are not particularly flexible.

    Another comment on the fact that Denmark doesn’t have storage: Norway does. Take a look at Danish wind data and compare that with DK-NO electricity flows. Not saying that it’s a bad thing – in many ways, it is a textbook case of maximising the use of wind power (in terms of CO2, does it really matter if the wind gets used in Denmark or Norway)?

    Great stuff!

    Kimi Arima
    Wärtsilä Power Plants

  • Dave2020

    “How will variable wind and solar power affect the grid? And how much electricity will need to be stored?”

    Ask the wrong questions – you get the wrong answers.

    NO electricity will need to be stored, WHEN enough renewables deliver electricity from stored ENERGY, and you won’t need a very large capacity of stored energy to get the grid running sweetly at lower cost.

    A balanced mix of renewables plus an expansion of technologies such as BEVs, will drastically cut the “need” for dedicated grid (battery) storage AND limit the flow of cross-border transfers of electricity.

  • Russell

    These analysis always assume that storage will be about as expensive as it is now don’t they? I think more realistic would be if you use $100-200 per kWH as that will surely be available in 10+years. Many battery companies have made good progress towards that already.

    • Bob_Wallace

      I’d cut that 10+ by two and change the sign to a “-“.

      Aquion says that they are going into production in 2013, they are currently building their factory. And their price target is <$200/kWh.

      Ambri has operating prototypes and expects to be in production with their liquid metal battery in a couple of years. Their price should be even lower.

      Germany is not a 'stand-alone' country. Germany constantly buys and sells electricity across its boarder. The larger the European grid becomes the more renewable energy will be usable without adding storage.

      A study that tries to determine how much renewable energy Germany could use without taking into consideration the wider European system is likely to generate too low a number.

      • Russell

        “baseload” as a useful concept will be close to obsolete when such a thing happens. Some other metric that takes into account the percentage of power needed time shifting will be needed. day/night vs seasonal energy production will probably also need distinguishing.

    • Agreed. Forecasts have clear built-in bias… when done the way almost everyone does them.

      • Russell

        I wonder if there are any forecasts then where storage costs <$100 kWH and solar is 20-30c per watt. Or are the results an obviously foregone conclusion in that case.

        • Bob_Wallace

          I don’t see how we do much more than guess at this point.

          For example, will storage be “end user friendly” and get installed in large amounts in people’s homes and apartments? Since retail users pay more for electricity they stand to save more by storing electricity during low price hours and then using that electricity when rates rise.

          Or will something like Ambri’s liquid metal batteries provide such cheap storage that they will get installed on a large scale at the utility level? I’m not sure that molten metal would be very acceptable in our residences.

          I can see a future in which end users become major electricity producers as solar prices fall. Solar reaches parity at the retail end much sooner than at the wholesale level. We could see enormous amounts of homeowner and commercial solar. By the time solar drops low enough to compete at the wholesale level we might have enough installed.

          That would put utility companies in the business of providing storage and fill-in power, covering the hours when the Sun isn’t shining.

          It’s going to be very interesting to watch….

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