In answer to this http://k.lenz.name/LB/?p=4236 especially the comment about the prospect of a whole country becoming a net electricity exporter

So as I said on twitter, France at one point was over the 100% threshold(1)
It’s no more the case since it’s electricity consumption rised around 9 TWh/y for the 10 last years, which is around the production capacity of a 1400 MWh nuclear reactor, and no new reactor was built during this period.
Norway has also more than 100% hydroelectric capacity, even though most of their money comes from exporting gaz&petrol. But their grid is connected with Netherlands now.

But the story of the overproduction period in France is not so rosy, and exemplifies that things get a lot harder as soon as your renewable/nuclear production begins to become significant wrt your total consumption.
You just can’t store the electricity you produce at the wrong time.

So France is exporting energy at night at a very low price, because nobody is consuming much, and import backs at peak consumption very expensive, and very CO2 loaded electricity. This also pushed EDF to try to get people use more electricity locally, let’s put electric heating everywhere and not make much isolation effort, let’s use electric water-heater with a programmer so they run at night and store the heated water all day.

The fact it’s nuclear actually helps because the situation would even more difficult with most of the renewables. First it’s completely predictible, so you can at least forecast what you’ll do. And then at least the base of the peak use is guaranteed to be absorbed, so you have only the problem of what is above it to solve. Finally we didn’t spend at much for the hard to use overcapacity as would be the case with renewables.

As the following two pages show, sometimes with renewables, sh*t happens :
– wind turbine curve : http://clients.rte-france.com/lang/fr/visiteurs/vie/previsions_eoliennes.jsp
– Consumption curve : http://clients.rte-france.com/lang/fr/visiteurs/vie/courbes.jsp
Yes, they are almost completely inverted. Wind produces most at night when nobody needs it, and least at noon when it’s most needed. This means you’ll start to have adaptation problems when your wind production is a lot lower that total consumption.
At least for solar, the curves are better, but in winter the consumption tends to get quite high when the sun sets (cooking food, rising up heaters) and solar produces nothing anymore.

Actually France was able to reach 80% nuclear by finding a way to store large amounts of electricity, using massive amount of hydro-electric water storage.
But you really can’t expend that at will, France is not far from using 100% of the theorical available capacity. And with renewable that have an even higher need for storage, there’s no way out. Or you just throw away the electricity.

OK, I may sound anti-renewables. It’s not the case.
I’m just asking for realistic renewable plans, that stay realistics at a large scales, when problems that are swept under the rug sometimes make what’s apparently working properly at a small scale not work any more at a larger one.

Biomass is one of the only renewable that’s on demand, it probably should be developed more.
Concentration solar allied with molten salt (like desertec) can also be a good solution for that major energy storage problem.

(1 )- at least for the non-carbon total, maybe nuclear alone but I need to get back to the 2001/2 numbers to check that. In 2005, nuclear alone was 89% of consumption, and with hydro and various renewables it reached 102%.