08.10.2012
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Energy transition

Little power storage or coal power needed for 40% green power supply

A study conducted this summer by German engineering association VDE finds that there will be little need for power storage if Germany increases its share of renewable electricity by around 50%. And perhaps even more importantly, the engineers show that baseload power – coal and nuclear – will have to go as the country switches to renewables.

Internationally, there are great doubts about whether Germany will be able to switch from nuclear to renewables without ramping up coal power – a concerned not common within Germany, however, as a recent study (PDF in German) published by Germany's VDE Association for Electrical, Electronic & Information Technologies shows.

The VDE is not primarily a green organization, so the findings are all the more interesting – both in terms of what was investigated and in terms of what was assumed. The main question in this study is how intermittent wind and solar power will affect the grid and how much electricity will have 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.

 - German engineering association VDE believes that the need for storage will be modest but to a 40% share of renewable power, at which point the need will increase. But the chart 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 (both fired with biomass and fossil fuels) along with gas turbines running on natural gas and power-to-gas, a way of storing excess power seasonally.
German engineering association VDE believes that the need for storage will be modest but to a 40% share of renewable power, at which point the need will increase. But the chart 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 (both fired with biomass and fossil fuels) along with gas turbines running on natural gas and power-to-gas, a way of storing excess power seasonally.
VDE

The findings do not come as much of a surprise. Renewables International has already calculated based on current statistics that Germany will not need to make major changes to the grid or require a lot of power storage if it reaches its current targets for wind and solar, at which point the country will roughly have 40% of its power from renewables. In the first half of 2012, Germany had around 25% renewable power, and the main effect has been offset power from natural gas turbines up to now, but increasingly renewables are cutting into the baseload. Neighboring Denmark, however, already has 40% renewable power and has managed to make do without major power storage up to now.

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%.

For international readers, one of the assumptions is perhaps even more interesting than all of these findings. One of the charts (see above) shows not only that nuclear will disappear (the nuclear phaseout is national policy), but also that coal power will be ramped down considerably, practically disappearing by the time the country reaches 80% renewable power. Here, we see why the international community misunderstands what Germany plans to do with coal. 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. So if Germany is currently failing to communicate its plans to phase out coal power over the next few decades, it's because there is a consensus within Germany that this will happen, not a discussion about whether it should. In other words, Germans see no need to talk about these plans with each other, so they do not recognize the need to tell the outside world. (Craig Morris)

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6 Comments on "Little power storage or coal power needed for 40% green power supply "

  1. Scott - 01.11.2012, 23:53 Uhr (Report comment)

    Hi Craig, I guess what I wanted to know is what the units were for storage. GW, as I'm sure you know, is the rate of change of energy -- not energy -- so I can't figure out from the article how much storage is envisioned. To specify how much energy is stored (equivalently, how big the battery or the pumped storage reservoir must be) it's necessary to multiple the rate by some unit of time GW hour is pretty common, but GW day is also used. But for seasonal storage, somebody might talk about a GW rate sustained over several months. So, the storage units could be GWh, GWd or GWm the differences in the amounts of stored energy is pretty big.

  2. Craig Morris - 15.10.2012, 14:09 Uhr (Report comment)

    Scott, "14 GW of short-term and 18 GW seasonal power storage": short-term storage will probably just be batteries and pumped storage, which can be used to shift power availability for a few hours. Seasonal power storage in the VDE study is power-to-gas, since excess renewable power in the summer (especially solar power) can be stored as gas in the country's natural gas pipelines until it is needed in the winter.

  3. Scott - 11.10.2012, 00:55 Uhr (Report comment)

    Would 40% renewables raise prices by 10% or is it 80% renewables? The articles seems to say both, although one number is worst case and the other is "roughly."
    Also, what does "14 GW of short-term and 18 GW seasonal power storage" mean? Energy storage systems have to store energy (GWh or some unit like that). If this is some kind of average rate of energy input over the year, what's the peak amount of energy stored?

  4. Photomofo - 11.10.2012, 03:25 Uhr (Report comment)

    I'm sure we'll get more solar if we prioritize solar and figure out how to use the electricity when it's made. We shouldn't be focusing on making batter batteries as job one. We should focus on making smarter appliances and becoming more responsible energy consumers. Once we've maxed out smart appliances and good behavior we can come back around to batteries - that's a ways away.
    Consider that you double your costs with battery storage. Pumped hydro is an interesting option but even if all of the planned projects Germany has on the table go through that's only another 8 GW of storage.
    I'm a big fan of thermal storage (huge potential - much larger than PHS) but I don't really consider this true storage because you're not planning on getting electricity back - you're planning on getting hot or cold. Thermal shifting is more of a usage strategy than a storage strategy.
    But like I said... The storage thing is used by advocates AND detractors. We as a community need to get a grip and realize that storage is not important at this point.

  5. Craig Morris - 08.10.2012, 17:03 Uhr (Report comment)

    Photomofo,
    If I understand you correctly, the answer is that they want storage rather than conventional capacity & lost renewable power.

  6. Photomofo - 08.10.2012, 16:07 Uhr (Report comment)

    "The findings do not come as much of a surprise.'
    If this is true then why do renewable advocates and detractors alike insist on prioritizing storage projects?

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