[ag315]

Correct--while the sun sends an enormous amount of free energy our way, it's maddeningly diffuse and requires enormous investments of energy and materials to capture it in a usable and reliable form. The Wynn in Vegas has a 160 acre solar farm in some of the sunniest land in the country and it provides...almost enough energy to power a single large hotel.

None of this is to say that solar power is bad, just that we should have measured expectations.

[myshpa]

Just 254x254 km of solar panels should be enough for the whole world.

https://www.dlr.de/tt/Portaldata/41/Resources/dokumente/inst... - page 25

[bitxbitxbitcoin]

Especially if it were close enough to the sun to start making a cube!

[causi]

1,370 watts per square meter isn't what I'd call diffuse. We're just not good at harvesting it.

[ArnoVW]

A typical nuclear station genrates 1 Gw. You'd need 1000000 square meters (=1000 sq km) to generate the same thing.

Oh and we can only capture 20-30 % of the energy of the total light.

We're going to need solar power, and fossile fuel is madness. But to deny that solar power is not 'dense' seems irrational.

[causi]

1000000 square meters is one square kilometer, not one thousand. It's also less than half the acreage used by my local nuclear power plant.

[fhars]

1000000 square meters are one square kilometer. Which is probably only about ten times the area required to build a nuclear power plant.

[epistasis]

Dense is a subjective term, and solar is without a doubt a dense enough energy source.

Compare the amount of land needed to power the US with solar to the amount we use to brew a small amount of ethanol as a minor energy sourced. We can completely power the US with a fraction of the land that we currently use as a subsidy for corn farmers, who grow more corn than we can eat.

[ag315]

While I'm less optimistic than you on solar power, you're absolutely right about ethanol, which is easily one of the worst and most inefficient power sources we could have possibly chosen to invest in. It's a significant indictment of the US political system that so much money was shoveled into it.

[epistasis]

I'm not sure why you are subjectively calling my number-based argument "optimistic." What do you mean by that?

[ag315]

Happy to discuss the numbers of your numbers-based argument, but you didn't cite your sources.

[Schroedingersat]

Now include the largest uranium mines like inkai in your area calculation. Or alternatively any recently opened coal mines.

Then include that any solar panels feeding variable load can go wherever (like roofs and parking lots) and take no land but instead enhance the other use.

Then include tilting agrivoltaics (which increases yield for heat sensitive crops and makes animals healthier).

Dedicated utility PV in a good area has a higher area energy density than any scalable power source except gas. Include dual use and it has the lowest land impact worldwide. Specific power is pretty damn good too, about 20W/kg (or 5-8W/kg net, so slightly better than nuclear).

[ag315]

Strategic installation of solar panels certainly helps maximize efficiency, and is in general a great idea, especially in some areas. But to your point about the space taken up by uranium and coal mines, that's only a fair comparison if you also calculate the mines needed for things like lithium, copper, etc. that would all go into a solar-oriented power grid.

[Schroedingersat]

It's not because they're no longer needed once the panel is produced. That would be analogous to the sand and copper and steel and indium and cadmium and gadolinium and chromium and zirconium and nickel and silver in the nuclear plant (and fuel cycle). All of which except silver outmass minerals of similar rarity and mining impact in the solar panel (and that is quickly changing). Even then it's questionable because most of the nuclear reactor cannot be recycled, but the solar panel legally must have recycling prepaid in many jurisdictions.

You're welcome to include mining for the entire supply chain of solar and exclude the supply chain of the generator for thermal though, it doesn't change how one sided the land use is in solar's favour.

[ag315]

"No longer needed once the panel is produced" The land used for the mining isn't land that we're just getting back--given the costs of making it useful again for anything else, space used for a lithium mine is in almost all cases essentially going to be gone for good. This is of course true for other mines as well, but your notion that lithium is an exception is a curious one.

"All of which except silver outmass minerals of similar rarity and mining impact in the solar panel (and that is quickly changing)" Nuclear reactors require relatively small inputs of these metals compared to the metals used in solar panels, and the huge capital invested in making solar panels less resource-intensive could also be applied to nuclear, if we wanted to do so.

"Even then it's questionable because most of the nuclear reactor cannot be recycled, but the solar panel legally must have recycling prepaid in many jurisdictions." But again, reactors are small compared to the millions of panels that are necessary to be the equivalent of one plant, and furthermore plenty of those materials can be and are recycled, especially in France (the entire history of the American nuclear energy program have created less waste than solar panels have in just a couple decades). And, again, innovations that make solar panels more recyclable (which we absolutely need because right now they mostly just produce massive amounts of toxic waste) could also be invested in nuclear recycling. I did get a good chuckle out of your vague "many jurisdictions" though.

[ag315]

1370/sq km is at the atmospheric level. The amount that actually reaches the surface is significantly less.

[causi]

Significantly less, but not debilitatingly less. For a panel in direct sunlight and adjusted to point directly at the sun, the ground value is 1,050 watts per square meter.

[geysersam]

That must be a seriously energy hungry hotel!

160 acres are 1x1.6 kilometers. That should give about 150 MW during the day.

(Same as power consumption of 50 000 aircons.)