I took a break from doing the layout for the high power management board I am designing to look a little further into this.

The US Department of Energy says that a solar power plant needs 75 times more space to generate the same energy as a nuclear power plant.

On the other hand, Shellenberger says you need 450 times more land for a facility like Ivanpoh to generate the same amount of electricity as the Diablo Canyon nuclear power plant. OK, this is something we can sink our teeth into.

Thankfully we have data [0][1]:

Since this video was published in January of 2019, I'll use numbers from 2018. In other words, this is that date he had to work with in making these assertions.

Ivanpah Solar, 2018
Power Generation: 0.392 GW
Net Energy Generation: 761 GWh (Solar only. This plant burns natural gas as well!)
Site Area: 3500 acres

Diablo Canyon Nuclear, 2018
Power Generation: 2.256 GW
Net Energy Generation: 18214 GWh
Site Area: 12 acres

Anyone not familiar with solar energy would scream "Wait a minute! Diablo Canyon only puts out six times the power!". Well, sure, except that this is not the right metric. A nuclear power plant outputs the rated power nearly 100% of the time, 24/7. A solar system cannot do this at all. In fact, output only reaches the rated peak for a few minutes (seconds?) each day and only during a few days of the year. Here's a chart of daily output of my own 13 kW solar array:

https://i.imgur.com/LTMNDO1.png

As you can see, it only reaches about 8 kW in July. It peaks out at about 11 kW in April. Thermal solar would follow a similar curve simply because, well, the sun is the sun and things move as they do. The curve isn't flat at all, it's roughly an inverted parabola.

To state the obvious, a solar generator does not put out useful power between, say, 8 PM and 8 AM. A nuclear power plan would put out rated power 24/7/365.

To drive the point further, here's typical month-to-month energy production of my 13 kW system for 2021:

https://i.imgur.com/EQc8EDD.png

You can easily see that the ratio from the best to worst months is about 2 to 1. I produce about 2 MWh in April/May and half that in December/January. Most people who don't understand solar assume that the peak is in summer. Not so. Solar panels have negative thermal coefficient. That means they produce less power when they get hot. April/May have the right combination of solar radiation and lower temperatures to help produce more overall energy.

Yes, I have generated nearly 69 MWh so far. Cool.

It's a long way to drive home the basic point: You cannot compare the rated peak power of a solar plant to the power rating of a nuclear power plan. The only valid comparison you can make is of the energy they produce over time.

In this case we have 18214 GWh for Diablo Canyon Nuclear and 761 GWh for Ivanpah Solar. That's a ratio of 24 to 1. In other words, you need 24 Ivanpah power plants to produce the same energy Diablo Canyon Nuclear power plant makes.

Now let's apply this to the land they utilize. How much land would the 24 Ivanpah solar installations need to be equivalent to the nuclear power plant?

Equivalent area = 3500 acres x 24 = 84000 acres

What's the ratio then?

84000 / 12 = 7000

His claim of 450 times more land does not seem to be correct. In fact, it is low by a full order of magnitude.

The US Department of Energy says 75 times. The truth is likely to be somewhere in the middle.

To get a better sense of this one has to have a look at the actual generating surface area for Ivanpah. The quoted area is for the entire facility, not the generating portion. Here's where Google satellite view can help:

https://www.google.com/maps/place/Ivanpah+Solar+Electric+Gen...

I used the measuring tool and added-up the rectangular areas enclosing each of the three arrays. The number I got is 3584 acres, which matches up nicely with the data I got before. Hmmm. What's the story?

Here's Diablo Canyon:

https://www.google.com/maps/place/Diablo+Canyon+Power+Plant/...

If I draw a square around the extents of this plant, I get about 500 acres. Using this number:

84000 / 500 = 168

So we have numbers between 7000x and 168x based on very basic analysis. My measurement for Diablo Canyon included parking lots and a bunch of land that is undeveloped. Well, we know you need buffer zones around any kind of power plan. What happens if, instead of measuring the area of Ivanpah as three separate rectangles I do the same thing and enclose the entire thing inside a rectangle? In that case I get 7680 acres.

Taking this into account:

(7680 x 24) / 500 = 369

Clearly this is a matter of how the areas where computed. None of this data is included in the TED talk video, of course. However, here's a key point: There isn't a 1 to 1 equivalency at all. We are looking at a range between 75x (US DoE) and several hundred.

In engineering we often do something called "ROM" analysis, where "ROM" means "Rough Order of Magnitude". The idea is to understand if you are anywhere close to what the real answer might be. The answer here is that, yes, he is. In order to get a better indication of what he had in mind we would have to understand what comparison he aimed to make. The US DoE number is based on an average 1 GW nuclear power plant when compared to an average photovoltaic (not thermal solar) plant of equal power output. It is my guess that the thermal solar facility might just do worse than straight photovoltaic.

As you can see, it takes a tremendous amount of work to evaluate and validate an argument. None of the above evaluates the validity of this one claim based on anything the man has ever said, only what he claimed to be true in this specific case. The analysis tells me that, to a ROM, what he claims is accurate in that there's likely a hundreds-to-one relationship in land utilization for equivalent solar power.

The truth isn't easy to dig-up. This is why most people simply accept what they are told. With enough repetition most people "know" everything, when, in reality, they likely know nothing at all.

[0] https://en.wikipedia.org/wiki/Ivanpah_Solar_Power_Facility

[1] https://en.wikipedia.org/wiki/Diablo_Canyon_Power_Plant