Elon Musk appears to be a confused man. For some reason he imagines that if you covered a nuclear power plant with solar panels instead, the solar panels would generate more electricity. More evidence that he is an overstretched individual who is at times out of his depth and not some Tony Stark esque figure on the verge of saving the planet – he should leave that to an irrational elderly Argentinian.

I wrote about this a few days ago, but at the time I wasn’t completely convinced Musk would actually have said something so ignorant and stupid. Surely a man out to save the planet with solar panels and batteries would understand something as basic as how much land they occupy. Apparently not.

The offending statements are made at 17.30 into the video below.



Musk’s claim is that if you covered the entire area of a nuclear power plant, including the so called “clearing area” of the plant, that most of the time the solar panels will generate more electricity.

This is simply not true.

In his recent book, Vaclav Smil provides the first quantative overview of the spatial requirements of renewables. Smil’s numbers make it clear that there isn’t a single nuclear power plant on the planet where Musk’s claim would be true.

Desert solar farms produce electricity with an average power density of around 10 W/m2 (see calculations by David MacKay for PV here and here). In contrast, nuclear power plants typically have power densities in excess of 100 W/m2, and regularly 1000 W/m2.

In my previous post I compared the area covered by Torness nuclear power plant with desert solar, showing that a solar plant in the desert would cover far more land.

But, let’s a try a couple of others.

First, Gravelines Nuclear Power Plant in France. Gravelines has a total capacity of 5.7 GW and an average output of around 4.4 GW. To get this with desert solar we would need roughly 440 square kilometres of land to be covered in solar panels. Gravelines Nuclear Power Plant is located between the town of Gravelines and Dunkirk.

The map below shows the area required for desert solar to generate the same amount of electricity as Gravelines. I have calculated this so that it is roughly a square of equal sides.

As you can see the solar farm would need to stretch all the way from Dunkirk to Calais and cover the entire town of Gravelines. In contrast the nuclear power plant is a relatively small industrial facility on the outskirts of Gravelines that is barely visible on this map.

Let’s look at another big nuclear power plant. Bruce in Ontario. This has a similar capacity – 6.2 GW – and an average output of around 5.1 GW. So, we would need around 510 square km of desert solar to replace the generation with solar panels.

Here is what this would look like on a map. The left hand map shows the location of the Bruce power plant. The right hand map zooms out to show a rectangular area, centred at the location of Bruce, required for desert solar to replace Bruce.

These maps tell a rather different story to the one told by Elon Musk. Solar farms take up at least ten times, and often one hundred times, more space than a nuclear power plant.

And the maps above may make things look better for solar than it really is. I have compared the nuclear power plants with desert solar. We do not all live in deserts. Nuclear power plants are also capable of generating 24/7. Solar power plants cannot do this. Genuinely replacing these nuclear power plants with solar would clearly require much more land to factor in storage requirements and the lower output of panels in winter.

Additional thoughts

After watching the video again I now seem to realize where Musk is going wrong. He seems to be confusing the W/m2 in capacity of an individual solar panel with the W/m2 in output of a solar farm. This of course would result in his calculation being out be a factor of ten, simply because solar panels to be spaced apart and average output is at most 20% of capacity. If Musk made this mistake, then it is probably time the media stopped treating him as some kind of Tony Stark figure, and instead treated him as someone who dabbles in energy as a hobby.

Recommended reading

Vaclav Smil’s recent book Power Density provides the first quantitative overview of the spatial requirements of all forms of generation.

David MacKay’s book Sustainable Energy Without The Hot Air has an excellent discussion of the spatial requirements of large scale renewable energy. (Available at Amazon or as a free ebook.)

Note on maps

I have produced these maps using R and the package ggmap.