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This picture has been floating around the internet

enter image description here

On May 8th, 2016, Germany's solar, wind, hydro and biomass plants generated so much energy, power prices actually went negative.

Is this true? I was under the impression that while renewable electricity production was on the rise it still was nowhere near enough to meet the needs of a major nation. Also, if this claim is true, how much power was produced by non-renewable means on that date?

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    Note that the claim is that power (i.e. electricity) prices went negative, not "energy prices". They're different. Electricity is a minority of energy consumption. – EnergyNumbers Jun 2 '16 at 5:35
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    Overproducing energy at a single day doesn't mean that the energy production meets the needs of a major nation. – Christian Jun 2 '16 at 8:59
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    @AndrewGrimm in Germany, electricity is about 15-20% of primary energy consumption (as it is in Australia) – EnergyNumbers Jun 2 '16 at 10:30
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    @Christian It wasn't even an entire day, just during the hours of peak solar input (at the longest). Getting adequate power at night is still a huge problem. – wedstrom Jun 2 '16 at 22:17
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    This is a self limiting problem; firstly there is equipment on the market that will convert excess electric power into gas that can be put into the gas grid. Then we have lots of users of heat (swimming pools, paper factories etc), that could heat with electric power if it was often cheaper then gas, switching between the two sources of heat. So if the cost of buying electric becomes low enough for a reasonable number of days each year, a market will be created for it. – Ian Ringrose Jun 3 '16 at 9:57
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This is pretty much true, and has happened multiple times in the past. In fact, they were introduced in the German intraday market in 2007.

For example, the same situation occurred in May 2014, when prices for energy became negative.

enter image description here

However, the reason that renewable energy had temporarily negative prices is that it is difficult to store energy, and that only a limited proportion of excess energy can be exported due to transmission capacity constraints.

Power has to be used as it is generated, and many power plants cannot be stopped temporarily without large losses to efficiency and incurring significant costs. In those cases, the power plant operator may choose to pay for power to be consumed, in order to not have to temporarily shut their power plants down.

The EU commission document explains this:

The frequency of occurrence of negative price episodes rose in the last part of the observed period as the costs of ramping up or down of some conventional plants are significant.

Regarding your second question, according to EnergyTransition.de quoting Agora Energiewende, the renewable power production reached 95% during noon on 8th May 2016, driven by the massive amounts of solar energy production.

enter image description here

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    Some words about WHY: As you wrote, you can't simply shut down a conventional power plant just to switch it on a few hours later again. But you can easily shut down wind plants, and solar cells even don't care if the power isn't consumed. BUT a law to support reg. energy (EEG), says (§8): The grid has to privilege power from reg. energy over conv. energy, and it always has to take all available power from reg. energy. The grid even can't ask the plants to reduce their power output. – sweber Jun 2 '16 at 7:28
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    @MarchHo: Yes and no... This law changes all few years, and I didn't notice. Sorry for that. The most recent version is EEG2014, and the old §8 now is EEG2014 §11 And §14 now says the grid can now also ask larger reg. energy plants to reduce power output, but latest one day before. So the situation isn't that serious any more, but it's still existing due to the limitations. – sweber Jun 2 '16 at 8:06
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    Note: what went negative are not prices for renewable energy (those have minimum price guaranteed by state), rather prices of energy in a general market. See en.wikipedia.org/wiki/Feed-in_tariffs_in_Germany The minimum feed-in prices is about 9 EUR / MWh. – Suma Jun 2 '16 at 11:46
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    @DanGetz "reg." is the abbreviation for "regenerativ", which is the "German" word for "renewable" in energy context, yes. – Alexander Jun 2 '16 at 13:14
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    @AmaniKilumanga They probably do do that - or the business has a live feed of power prices and does it themselves. I know really energy-intensive businesses (like aluminium smelters) will lower production when power prices rise and pick it back up when they fall - this would just be a continuation of that. – user253751 Jun 3 '16 at 7:14

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protected by Oddthinking Jun 5 '16 at 12:47

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