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Comment by hyperpallium | Hacker News Reader

I wonder what environmental impact truly large-scale solar energy will have. In that it is moving energy away from where it would usually fall on the ground/plants, thus reducing heat, less rising air, less photosynthesis etc. Perhaps additionally aid global cooling? Though that energy will mostly end up as heat anyway.

(Of course it's far better for the environment than present coal/petrol/gas/wood, and their energy initially came from the sun anyway, but it will still have some environmental impact.)

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As a sanity check, the earth gets ~1366 W/m2 * (6,371 km) ^2 * pi = 1.7e17 watts * 24h/day * 365.2425day/year ~= 1.5e21Wh/year ~= 1,500,000,000 terawatt hours/year. Humans use 155,505 terawatt-hour / year or ~ 1/10,000th of that much energy. (https://en.wikipedia.org/wiki/World_energy_consumption)

Further, it's all (99.99%) going to get released so net impact is going to be very local.

PS: In the end the real change would simply be changing the albino of the planet slightly. But, buildings and roads already cover far more land than solar is expected to anytime soon with minimal impact.

The problem here is that someone once did some cocktail napkin math with regards to dumping farm waste into the Chesapeake Bay and determined that the ocean is so enormous it was stupid to think some agro-waste would change much about it.

I can't find a source at the moment, my apologies. But suffice to say humans have a knack for considering their needs insignificant when in reality our Spaceship Earth looks ever more fragile the more we learn about it.

Hurricanes also produce Terawatts of energy. The question is the way the energy is turned into electricity, and how it's stored or backed up because an economy requires reliable electricity

I'm a supporter of solar, and trying to get it on my house.

But I also did some back of the envelope calculations that showed, just if we had enough Powerwalls to backup US peak demand for one hour it would require 10x the global annual mining production of lithium. And that's just one hour. And that doesn't include the electricity production.

It's generally estimated that US power, with good transmission, would require enough solar panels to cover the entire state of Massachusetts. I think you're right that it isn't the land cover that would have much effect, after all buildings and roads already cover a lot of land. I think it's sheer material production.

Mining is almost entirely powered by fossils, it has to be. And so is most transport. And so is recycling of metals. So the energy density of an energy source really is a zero sum game. If it takes a millionth the material for one source versus the other, that adds up.

Then in maintenance, solar farms are truly "farms"- they require a lot of water to wash away dust to operate optimally. A states' worth of water is significant.

Then in recycling at end of life, and this is why I got so excited about nuclear as a somewhat hippie child growing up around oil companies in Oklahoma, solar is going to require a lot of energy to recycle, while nuclear can produce energy in recycling its fuel.

The main reality check, to me, is: what is the energy density of this energy, and if emitting, how much pollution? Coal is far more energy dense than wind, which is why humans evolved from windmills and wood to coal. But it's so polluting which is why we are all working towards better sources.

20,000km2 sounds huge but:

The US currently uses 40% of the 84 million acres or 340,000km2 crop for ethanol production which is arguably pointless. So, if we swapped just corn ethanol for solar cells we would have 6 times more land area than the entire state of Massachusetts covered in solar cells (135,000km2). And if we feel ethanol is really necessary we only need 8% of the total corn crop leaving 32% for corn ethanol.

If this still seems like a huge issue the soybean crop is far larger. http://www.epa.gov/oecaagct/ag101/cropmajor.html

PS: As to storage, we don't need 100% solar wind and hydro can make a huge difference. Pumped storage is also far cheaper at scale; it's just impractical when scaled down to home use.

These are the sorts of deep questions that often go unasked as we humans look for ever greater efficiencies. I had to attend a seminar on geothermal wells presented by a group of ageing hippies. When I asked if any long term studies had been done on the affect of mass-geothermal well drilling and pumping cool water out of the ground and cycling warmer water back in, no one could even parse my question properly.

My impression was that the vast majority of sunlight Earth receives is wasted, and that solar panels just gobble up the waste (so long as they're built in, say, deserts or other places where they're not blocking out a whole lot of flora/fauna).

Wind and hydroelectric, on the other hand, could very well have significant environmental impacts if deployed on a sufficiently-large scale, despite being technically "clean" energy (aside from the non-clean energy and materials used in their construction).

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