Elon Musk is wrong about the land requirements of solar and nuclear, and by a long way

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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.

Click to enlarge

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.

19 thoughts on “Elon Musk is wrong about the land requirements of solar and nuclear, and by a long way

    […] offending statements are made at 17.30 into the video below. – Click here to read the full article […]


    crf said:
    July 13, 2015 at 6:09 pm

    Elon Musk is chairman of SolarCity.


    MorinMoss said:
    July 16, 2015 at 6:23 am

    From 18:30 – 19:00, Musk clarifies what he means by clear area and defines it as a zone around a plant of 3-5 kilometers so a circle of 30 – 80 kilometers.
    The city of Paris, for example, is quite far north – 900 km north of New York City, 2500 km north of Miami and 5400 km from the equator get ~0.75 – 5.25 kWh / sq meter daily across the year with a rough average of ~3kWh which corresponds to the daily insolation in late March and an average power of 0.25 kW / sq meter.

    For Musk’s “clear area”, that’s about 1.2 – 3.5 GW using solar PV of 20% efficiency.
    Elon may be off for solar vs nuclear in many places but not by much and he’s correct for a vast swath of the planet that’s very heavily populated.


      MorinMoss said:
      July 16, 2015 at 6:30 am

      That should be “a circle of 30 – 80 SQUARE kilometers”


      Robert Wilson said:
      July 16, 2015 at 7:48 am

      I’m going to mark this comment as “special pleading”.

      My post provides examples of existing nuclear power plants and compares them with existing desert solar farms. I don’t think you are actually responding to any of the arguments or numbers presented.


        MorinMoss said:
        July 16, 2015 at 2:51 pm

        What is so “special pleading” about showing what is possible, right now, with commonly available solar tech?
        The Dunkirk-Calais area is not a sunny desert and a solar farm in the Algierian wasteland won’t be powering French districts any time soon. But nuclear plants are and solar PV could, as is the case with neighboring Germany.

        If you wish to fixate on “desert solar”, then consider that California’s parabolic trough SEGS installations are 30 years old and have been providing up to 350 MW on 6.5 sq km (1600 acres) so an expansion to 30 – 80 sq km would give 1.6 – 4.3 GW on an area that’s 1/10th of 1% of the Mojave and with outdated technology.


        Robert Wilson said:
        July 16, 2015 at 3:21 pm

        It’s almost as if you think I compared nuclear with desert solar and not French solar because I wanted to rig my numbers. How bizarre.


        MorinMoss said:
        July 16, 2015 at 3:45 pm

        What I think is that it’s easily demonstrated that Musk’s specific claim is not wrong.
        There are other arguments to be made in the nuke vs solar debate on both sides but as Musk says he’s not opposed to nuclear and just a couple minutes later he & JB Straubel talk about the growth potential for utility scale electricity.


        Robert Wilson said:
        July 16, 2015 at 3:58 pm

        Easily demonstrated? If it’s so easy then demonstrate it. You telling it’s easily demonstrated seems like a waste of keystrokes.


        MorinMoss said:
        July 16, 2015 at 4:35 pm

        I thought I already had but you’d have to read my previous comments in their entirety to grasp it.
        If there is something you’d like me to clarify, please specify it.


        MorinMoss said:
        July 16, 2015 at 9:02 pm

        “because I wanted to rig my numbers. How bizarre.”

        What’s bizarre is you expecting no one to think that’s exactly what you did or were trying to do.
        One thing I don’t like about Elon is his typically haphazard & jumpy stutter in Q&A which makes it easy to miscontrue what he says or means. And he frequently mixes up power & energy which is an annoying error for a man in his line of business and technical savvy to make.
        But since nearly every word he utters gets recorded, then discerning individuals have the opportunity to re-examine what he says, in context, if they’re so inclined.

        Here, in a nutshell are his claims:
        1) Solar will make up a slight majority of electricity generation in “the long-term”
        Hey Elon, how about giving a slightly more precise definition of “long-term” than by using the distance between your thumb & index? Is it 10 yrs, 20, 50, more than a century??
        My opinion is that he’s wrong about it being even a slight majority but it’ll probably be a significant percentage, say 30% by 2030 – 2040.

        2) Each sq-km of Earth receives 1 GW of solar “energy”
        Elon, that’s POWER, not energy. Get it right and explain the difference to the noobs, FFS.
        Considering this talk was hosted by the Edison Electric Institute, it’s shocking (sorry) that no one pointed that out.
        Now, is 1 GW / sq-km true? Let’s look at a few disparate geographical locations.

        Location Month Avg Insolation ( MW per sq km )
        Calais, FR Jan 95
        Mar 201
        Jun 346

        NYC, NY Jan 188
        Mar 275
        Jun 347

        Yuma, AZ Jan 290
        Mar 386
        Jun 509

        Now, using the GAISMA data (daily insolation divided by length of day), it looks like Elon is wrong if he’s talking about power. The peak insolation MIGHT be double the average but even so, that won’t be year round and only in very, very sunny places which is why Elon may have specified “desert solar”.
        Even so, I’m going to call him wrong and by a factor of 2 – 5x which is still loads better than your estimates.

        But what if he did mean ENERGY i.e. GWh per sq-km?
        Then even in Calais in January, that would be 780 MWh / day on average rising to 5-6 GWh / sq.km/day in from May through August. Further south you go and more desert-like you get, the better the insolation.
        Daily solar energy for Yuma is ~300 MWh in Jan and doesn’t drop below 5 GWh from March to October and stays around 7 – 7.5 GWh from May through July.

        3) Nuclear zone “clear area”
        Here he’s talking about a “3 – 5 km zone with no significant construction” around a nuke plant.
        Judging by Google Earth satellite pics of Gravelines and Bruce, he looks to be right.
        Even when you look at densely populated Japan, the areas around its largest plants are very sparsely built up.
        Now, should we go with a radius of 3km, 5 km or something in between? Hmm….?

        Okay, I just noticed that the 2 nuke plants you choose are not at all typical, even when considering ones under construction. Gravelines is the largest, by far, in France and currently 6 largest in the world and Bruce is 2nd largest globally. So I’m comfortable taking the higher radius and rounding the area to 75 sq-km.
        Since Elon said desert solar and you were quite insistent on it, then we’ll use the numbers for Yuma, AZ.

        If using PV at 20% eff., that gives 75 sq-km * 7 GWh/day/sq-km * 20% conversion eff or 105 GWh / day.
        Gravelines at 4.4 GW gives 105.6 GWh per day; Bruce does better at 122.4 GWh per day.

        So contrary to your headline, Elon is not “wrong by a long way”.
        As I said, there are other arguments to be made for nuclear / against solar and vice versa and you’ve pointed to a couple but in terms of Elon’s specific remarks, he’s pretty close to being right.


        Robert Wilson said:
        July 17, 2015 at 12:29 am

        You really are a bizarre individual. So, I rigged things against solar by choosing desert solar for the comparison over French solar. I don’t know where to begin here. It’s like explaining why 1+1 does not equal 11.


        MorinMoss said:
        July 17, 2015 at 12:49 am

        You asked me to demonstrate. I did.
        If there’s an error, it shouldn’t be difficult for you to find.
        What’s bizarre is that you’ve only been able to call me bizarre and not refute my arithmetic.


    thedirtyho said:
    July 18, 2015 at 3:16 pm

    It’s not so much refuting the arithmetic as the logic.

    A comparison is made between desert solar and nuclear. You’re saying why not with French solar, as though the case is being purposefully skewed to make solar look bad.

    Out of French solar, and desert solar, which do you think will generate more?

    Therefore, by choosing desert solar over French solar, is it presenting a more or less favourable case for solar?

    Take your time . . .


    Swain said:
    July 18, 2015 at 3:48 pm

    MorinMoss – the point about using a big nuclear plant like Bruce or Gravelines is that they represent the best potential power density of nuclear versus the ostensible best potential of desert solar. That seems like a mostly apples to apples approach, although the reality is the size of nuclear generating plants is most often constrained by budget and politics. If there were the political will, we could put 3 or more units in every nuke…but as it stands only two or three in the U.S. Have more than two. With solar power, you can’t put desert solar in Northern Europe of course…but never mind that.

    The assumption that seems striking to me is the so-called ‘clear zone’ of nuclear plants. Musk appears to think that it’s completely empty. In fact, that area can have economic and social value as recreation land, farm land, wildlife/conservation land, and even other commercial uses. Correct me if I’m wrong but it seems to me paving the area with solar panels makes the land otherwise completely unusable – for humans or animals.

    The essential problem with Musk’s quote is that the sound bite is nonsense. Sure, once you dig Into his assumptions and caveats it’s possible for a lawyer to torture the language and claim some technical truth. But the sound bite by itself is misleading at best and pure bullsh at worst.


    Swain said:
    July 18, 2015 at 4:20 pm

    MorinMoss – are your numbers including capacity factor?

    Just to run thru a U.S. Example – the new Ivanpah solar plant in CA has a 392 MW nameplate and covers 3500 acres – which is 12-13 km2 or so. So expand that out to this mythical 75 km2 circle that supposedly represents a nuke’s actual area…and you get 6*392=2.3 GW nameplate.

    Gravelines has a 5.7 GW nameplate. So already 3x as big.

    Now you bring in capacity factor. Ivanpah claims .32 and put Gravelines at the overall average nuke capacity factor of .9

    That gives you:
    Big solar = 700 MW
    Big nuclear = 5.1 GW
    Quite close to an order of magnitude difference.

    By all means, check my math and assumptions -I am a little groggy.


      MorinMoss said:
      July 18, 2015 at 11:43 pm

      If you read my comments in their entirety, you are already aware that I said that Musk confused the issue by possibly conflating power & energy, or if you prefer, kilowatts and kilowatt-hour. And then I did the calculations to see where he could be right, or wrong. And further criticized his frequently imprecise way of answering questions.
      I also checked satellite maps of several nuclear plants in a few different countries to see what the “clear areas” around them looks like and is certainly does look like the areas around them are sparsely developed.
      Land used for solar PV doesn’t have to be single use and you can mount the panels higher and grow or graze under them – or you can go full commercial and mount solar panels on the rooftops, upper floors and install solar carports.

      Your number for Gravelines is a bit high – World Nuclear has its lifetime capacity factor at 75%.
      OTOH, Ivanpah is severely underperforming and there’s no announcement as to when it may be running more smoothly.
      Adding nukes reactors to existing plants is not that simple as you have to be able to cool them adequately.
      It doesn’t appear to be an issue for ones located by the ocean but inland plants in France, Spain & America have been idled during several heatwaves over the past dozen years.
      Not to mention the jellyfish clogging issue that has hit Sweden’s Oskarshamn and California’s Diablo Canyon.


    turnages said:
    July 23, 2015 at 1:41 pm

    Good on you MorinMoss for showing your calculations. But I think you overlook conversion efficiency.

    Your insolation figures per sq.km cannot be converted to electricity at anything like 100% efficiency. Typical values for PV solar are 10 – 20%, and solar thermal, around 30%.

    The required area for solar will then increase by a factor of from about 3 to 10, when this is allowed for.


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