France and Germany: real world comparison of nuclear vs. solar and wind
93% of electricity in France is carbon free. Most of the power comes from nuclear energy, but some comes from hydro, wind, and solar.
Germany is 57% carbon free:
There’s a lot less nuclear energy and a lot more wind and solar.
There’s also a lot more fossil fuel usage, especially coal.
Power in France costs 19 cents per kWh.
In Germany, it’s 30 cents.
France makes 51 grams of CO2 per kWh of electricity.
Germany makes 311 grams of CO2 per kWh.
Germany makes 6 times as much carbon pollution as France, and the price of electricity is 50% higher.
Solar energy advocates like to say that nuclear is too expensive. But nuclear clearly wins in this real world comparison.
Why renewable energy fails
Digging into the data for Germany gives a few lessons on why it’s so hard to build wind and solar at scale.
Here’s the German power mix for each week of 2021:
Solar and wind are complementary over the course of the year — solar (graphed in yellow) produces more during the summer. Wind (graphed in blue) produces more in winter. Throughout the year, the combined amount from wind+solar stays roughly constant.
The baseload power comes from coal (brown and black), natural gas (light grey), and nuclear (reddish brown).
On any given day, about half of the energy produced is carbon free.
If we look at individual days throughout the year, things are much more variable. We see times where wind generates almost enough for the entire grid. Here are a few windy days in February:
We see times where solar does reasonably well. Here’s a sunny week in May:
We also see times where both wind and solar failed. Here’s a week in December:
During that week, power was mostly from coal, with some help from natural gas and nuclear.
Is the situation going to get any better?
Imagine that Germany built more solar panels. At first this would help out, they could build maybe 30% more and then solar would be making 100% of the electricity in the middle of a sunny day.
The other power plants would have to turn off during the daytime and back on at night. That’s inconvenient for nuclear reactors, I’m not sure how it works for coal. But let’s assume that’s all manageable.
Once they build more solar than that, things get awkward — solar would start to make more than 100% of the electricity needed in the middle of the day. Germany doesn’t have much battery storage to use the extra. They could just disconnect the panels from the grid, nothing bad will happen. But the value of that additional electricity goes to zero. Companies lose the incentive to build more solar panels than that because they can’t sell all of it.
Germany has almost enough windmills to go 100% wind powered on some winter days.
If they built, say, twice as much wind energy, it would be wasted on a winter day but it still wouldn’t do much good on a calm day in summer.
Germany could switch all the coal plants to natural gas, which emits about half as much CO2. But Germany gets most of their natural gas from Russia, so that creates a political risk.
Even if they did that, power still wouldn’t be as clean as France.
To do better, Germany would have to go nuclear or build a huge amount of battery storage. And batteries are very expensive — in a previous article I estimated the cost of a nation-sized solar farm for the United States and of a nation-sized battery. The batteries would cost 15 times as much as the solar panels.
Planning for the worst weather of the year
Intermittency is the downfall of renewables. Building a new solar farm is cheaper than building a nuclear reactor, just like the solar advocates say.
But you can’t just compare the cost of nuclear to solar, you need to compare nuclear to solar and a battery backup, or nuclear to solar with coal as a backup.
In my other articles, I just guessed that a 3 day battery would be good enough to deal with any weather conditions.
We can use the data from Germany to figure out exactly how big a deal intermittency is.
Solar is more predictable than wind. It makes some energy every day, but less in winter or if it’s cloudy. Solar output can be 10 times lower on a cloudy day. And there’s a chance it could go to zero if it snows on the solar panels.
Could Germany just build a lot more solar panels, enough to power the whole country on a cloudy winter day? Then they would only need enough battery storage for one night, not for 3 days. That would cut the battery cost down.
I downloaded the data from Germany and graphed peak solar power at noon, for every day of the year:
Power peaked at 9,000 for the sunniest day of the year. The worst day was only 300.
That leaves no good options.
Germany would need 30 times as many solar panels as they have now, to have enough power for a winter day. Actually, a bit more than that, because winter days aren’t just less sunny, they’re also shorter.
Or they can install batteries, which I estimated would cost 15 times as much as the solar panels, for only 3 days worth of storage.
3 days of storage wouldn’t even be enough for Germany, solar doesn’t get high enough on a good winter day. They need solar and wind.
If the United States ever goes solar, they might find it easier, because there are some parts of the southwest where the sun shines in winter:
Southern Europe might also have a better chance with solar, Spain gets more sun than Germany:
Germany could not get by on solar + batteries. They would need a mix of solar + wind + batteries.
Wind is less predictable than solar
Here’s German wind power output, for each day of 2021:
Wind storms are stronger in winter than summer. But there are weeks where the wind doesn’t blow, all through the year.
Germany could build a lot more wind power than they have now, then charge the batteries during a windy week.
The time between wind storms is as long as 10 days, so they would need about 10 days of battery storage.
The combination of solar+wind still doesn’t make a reliable energy source. Here’s a comparison of daily wind and solar power production for a year:
The highest daily output for wind is much higher than for solar. That’s because wind can make 24 hours straight, given the right weather. Solar will never work at night. The noon peak production for solar is similar to the peak value from wind. To get a higher daily amount of solar, Germany would have to build more than they can use in the daytime and store the extra energy.
If we add together the daily wind and solar output, it looks like this:
There are still weeks that go by with a low combined amount of sun and wind.
Suppose that a value of 10,000 on that graph is enough to power the whole country. On a bad week, solar+wind output is around 2000.
For a reliable grid, Germany would either have to overbuild solar and wind by a factor of 5, or they’d need a whole week of battery storage.
So, to catch up with France’s low carbon emissions, power in Germany would become at least 5 times more expensive than it is.
Other countries in Europe will have the same choice — wind speeds in Germany are about average, compared to the rest of Europe. Scandinavia and the UK have more wind. Spain, France, and Italy have less.
Nuclear is the only proven solution
A few countries in Europe have done as well as France, or better:
Green countries on this map are producing the least carbon, brown countries the most.
How did each green country achieve it?
Norway is almost 100% hydroelectric.
Sweden is 50% hydro and 50% nuclear.
Switzerland is 50% hydro and 50% nuclear.
Finland is 33% hydro, 33% nuclear, 33% gas.
Belgium is 60% nuclear and 40% fossil fuels.
Iceland is 60% hydro and 40% geothermal.
Austria is 70% hydro, 10% wind, and 20% fossil fuels.
Not a single country became green by using solar and wind.
Countries with a large amount of available hydropower can go green. Iceland has the rare ability to use geothermal. Otherwise, the only solution is nuclear.
Most of the US does worse than Germany:
California and Texas are about the same as Germany, with a mix of wind, solar, and natural gas. Washington state does better because of hydro power. The rest of the country pollutes more than Germany.
The US is on a path of building more wind and solar. This is a gamble that someone will eventually build a new battery that’s much cheaper.
If it doesn’t happen, they will end up in the trap that Germany is in, where the problem is only half solved.
The United States should also look at expanding the use of nuclear, the only proven solution for stopping climate change.
