19.09.2012
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Husum WindEnergy

Capacity markets little understood

In a conversation yesterday at Husum, two of Europe's "founding fathers" in the renewables sector were unable to answer questions about the need for backup power when not enough solar and wind are available.

At a panel discussion, Lyn Harrison, founder of Windpower Monthly, asked a question that tripped up two of Europe's most well respected supporters of renewables: Germany's Hans-Josef Fell and Denmark's Preben Maegaard. Both gentlemen had come to discuss how the renewables sector can go forward. Maegaard, for instance, gave an impressive presentation on how Denmark can start using excess electricity from wind power to offset imports of oil and gas for heating purposes; with wind power increasingly less expensive than imported fossil fuels, electric heating can be a useful, inexpensive way of "storing" excess green power.

But a seemingly innocuous question posed by Harrison showed that Fell and Maegaard, for all of their groundbreaking work, have not yet thought enough about an issue that is increasingly moving into the foreground: "What about capacity markets?"

 - At Husum, Fell and Maegaard both held inspiring presentations on how renewables can continue to grow, but they had little to say about what we should do when there is too little solar and wind.
At Husum, Fell and Maegaard both held inspiring presentations on how renewables can continue to grow, but they had little to say about what we should do when there is too little solar and wind.
Craig Morris

Essentially, the issue revolves not around what to do with excess renewable electricity – the issue addressed by the panel – but around what to do when not enough green power is available. In such cases, we have to resort to backup power generators, but they increasingly run for fewer and fewer operating hours each year because they are increasingly offset by renewables. As a result, the profitability of conventional power generators continues to be reduced, though demand for dispatchable backup power remains unchanged. In particular, power demand generally peaks in Germany on November evenings, when the sun never shines. So whenever there is not much wind on such an evening, Germany will have to have nearly 80 gigawatts of dispatchable power to prevent blackouts – a figure that has not changed over the past few years and will not change relative to the growth of photovoltaics.

Unfortunately, both Fell and Maegaard answered the question by pointing out what can be done with excess green power – which is not at all what Harrison asked. Fell is the co-author of Germany's Renewable Energy Act, without which Germany would not be where it is today in terms of renewables. Nonetheless, Fell and Maegaard's generation is used to reacting to charges that renewables will always be a niche energy source. Now that renewables are clearly out of their niche, Fell and Maegaard have been vindicated – but future steps moving forward will require a different focus and different argumentation.

No one today doubts that renewables can be a major source of power. The irony is that proponents of renewables now have to start thinking about how to protect the profitability of dispatchable power units – even the ones owned by companies that historically opposed the switch to renewables. (Craig Morris)

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5 Comments on "Capacity markets little understood "

  1. Robert - 20.09.2012, 10:34 Uhr (Report comment)

    In my view, the answer is small combined heat and power plants (MicroCHP and MiniCHP). They will produce heat and power when it is cold outside and solarenergie is low. As far as I know, the german gouvernement increased the amount of gouvernement money. A second point is, that CHP uses gas, which could be produced partly by excess renewable electricity from solar in summer and wind in winter.

  2. Photomofo - 19.09.2012, 21:46 Uhr (Report comment)

    Here's a treasure trove of links about storage water heaters.
    http://www.nnka.de/downloads-links/2-links

  3. Photomofo - 19.09.2012, 21:41 Uhr (Report comment)

    For me the easiest thing to imagine shifting is electric water heaters - heat pump water heaters (HPWH) in particular. There's minimal infrastructure required and the economics of a solar powered HPWH stand up solidly against gas and/or off-hour grid electricity. If you think beyond basic domestic hot water and space heating demand there's plenty of process heat situations that you can potentially shift load around - we're talking about TWh. As you point out, some of the displacement will be fuel but some of the displacement will be night-time electricity which means there should be a reduction in capacity requirements. It's not linear but it's there.
    This document give some stats.
    http://www.eurosolar.de/de/images/stories/pdf/SZA_01_08_Stadler.pdf
    There are lots of other areas where you can shift usage. It's a process. Have you been to a place where everybody hangs out their clothes to dry? You can reasonably expect that these people try to hang the clothes up to use the full warmth of the day to dry them. In other words, you don't wash clothes on a rainy day. You'd have to figure that home owners and businesses in Germany will quickly learn to recognize that they should dry their clothes, run their dish-washers and make other sorts of hay while the sun shines.
    Back in the early days of electricity the Barons like Insull figured out ways create demand for electricity at night. They built things like Coney Island for example. Over the course of time the utilities have tried hard to balance out load so they could run they're power plants at higher capacities. Our job going forward is to carefully reconfigure the load profile and see how much load we can shift to when it is sunny/windy. When you do that you lessen the need for capacity when it's not sunny/windy. I believe this is where most of the solution to the capacity problem lies.

  4. Craig Morris - 19.09.2012, 19:48 Uhr (Report comment)

    Photomofo, he is replacing gas and heating oil imports, not power demand now with power demand later.

  5. Photomofo - 19.09.2012, 19:35 Uhr (Report comment)

    "Essentially, the issue revolves not around what to do with excess renewable electricity – the issue addressed by the panel – but around what to do when not enough green power is available."
    These are the same issues. If you figure out how to use excess renewable electricity it means you won't have to use that electricity at some later time. The reduction in load at that later time results in a reduction in the capacity requirement. Fell and Maegaard answered the question appropriately even if they didn't know it.

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