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>Inevitably, some hot July week will come when a high-pressure system stalls over Europe, stilling turbines just when sunburned Germans reach for their air conditioners

The summer in Germany isn't that hot. Middle europe, not california. Accordingly, we don#t have air conditioners (in general)

These scenarios do happen. They're not always as straight-forward as the one suggested (low production/high demand). A few weeks ago there was a sunny/windy holiday in Belgium (May 28th). Due to overproduction and low demand they had to avert a national blackout by paying France to sink the surplus energy. In Belgium, renewables account for 7% of energy. That weekend it was 3 times as much.



I don't know about Belgium. Maybe air conditioners there are more common? In Germany, it is said that cold winters are more dangerous for the energy balance, as the cold also increases energy demand and the photovoltaik-cells aren't as useful as in a hot (and sunny) summer.


Please read again. Energy demand was lower because it was a holiday, nothing to do with air conditioners.


Thanks. I didnt get that fully, because i saw that reply as phrased as a critic to my statement, whereas it supports my point (which was, that high demand/low availabality because of the summer is unlikely in that scenario). Or not, but it is not a real critic on my statement.

Of course such scenarios happen, especially the situation you described.


It was an addendum, not a rebuttal ;)


PV cells are actually more efficient at lower temperatures. The lost production comes entirely from decreases in the amount of sunlight.


I had no idea too much electricity could be a problem? I was trying to read more about this effect but google has no answers for me.

Also, surely the obvious thing to do would be turn off some of the turbines in that situation?


- It's not just wind (turbines) but also solar.

- You don't have centralized access to all the facilities. E.g. small and medium-scale solar falls under the control of the owner AFAIK. Large scale wind also has other parties involved that don't want to miss out on income.

- Control of energy production on a national or regional scale follows prediction models, not only for demand but also price of resources such as gas and weather forecasts for renewables. So for a holiday they would shutdown a number of "classic" facilities to follow a day-ahead schedule. This probably increased the dependency on renewables for that day.

The big question "why didn't they shutdown wind farms": I don't know but I plan to find out.


As per the 2003 E.U. directive on renewable energy, renewables have priority access to the rid to offload their production. This is makes sense because it ensures full utilization of the assets and helps reduce their costs.

EDIT: grammar


Both the 2003 directive [0] and the 2009 directive [1] state that member states may give priority - with notion of exceptions for security. Maybe priority was indeed the factor, but it's not mandated on a European level.

[0] http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2...

[1] http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2...


The 2003 Directive you quote (2003/30) is for biofuels, whereas 2003/54 deals with renewable electricity. Both refer to 2001/77, which details the condition of access to the grid for renewables. The language is relatiely clear Art. 7 - 1, if we distinguish between "access to the grid" meaning in the first part "right to connect" and "right to output" in the second part.

> Without prejudice to the maintenance of the reliability > and safety of the grid, Member States shall take the necessary > measures to ensure that transmission system operators and > distribution system operators in their territory guarantee the > transmission and distribution of electricity produced from > renewable energy sources. They may also provide for priority > access to the grid system of electricity produced from renew-able energy sources. > When dispatching generating installations, > transmission system operators shall give priority to > generating > installations using renewable energy sources insofar as the > operation of the national electricity system permits.

However, it is superseded by 2009/28, which states in Art. 16 - 2 (a):

> Member States shall ensure that transmission system opera­tors and distribution system operators in their territory guar­antee the transmission and distribution of electricity produced from renewable energy sources

I believe the confusion stems from the distinction between right to connect to the grid and right to offload power to the grid. It seems clear the latter is indeed mandated at the E.U. level.


The problem is mainly economic. Wind and solar can produce with essentially zero marginal costs. (The cost of producing an additional kWh is negligible, if one is not accounting for upfront investments.) And therefore they can sell at any price (and generate additional revenue). This forces conventional power plants to shut down and there is possibly not enough reserve capacity if renewables fluctuate. (For engineering it is a problem which can be easily solved with an resistor ;)




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