Quote:
Originally Posted by Traditional_Ale
Wow! Thanks for this link! I'm going to post the picture anyway...
I'm out of thankses, so...thanks!
The black dots represent an area that if covered in Solar farms could supply the world's energy. The wiki link says assuming 8% efficiency, which given the location and the technology as it exists today I have little doubt is more than attainable. |
The energy is there, but getting it, storing it, and moving it are all challenges that solar (or other variable sources) haven't yet met IMO.
On a small scale it keeps getting better and better, and as a supplementary source it's great, but as a primary source I'm not so sure.
For example the Solar Two tower generates 10 MW. To do so reliably it has a molten salt store to store the energy. Molten salt is nasty stuff and they store it extremely hot, so there is a factor of risk there. Fortunately it's not flammable.
But just to give an idea, Solar Two has 63 cubic meters of molten salt. That's 63,000L, that's 2-3 tanker trucks worth. But that's for 10MW. To scale that up, the US needs 1,000GW of generation. So we have to scale that up by 100,000! 2-300,000 tanker trucks worth. 6.3 billion L, those big cylindrical storage tanks you see around hold a few million L, so you'd need thousands and thousands of them, and the equipment to withdraw the energy when needed, which has to be duplicated thousands of times over based on how much each can handle.
And the infrastructure for it all. And molten salt is probably the most space efficient that I can think of.
That's so you can supply power when there's a cloud or overnight, Solar Two has 40 hours of reserve with that, if the solar farm gets cloudy for longer than that you're toast.
Not to mention transmission, losses from transmission are huge, and with a single solar farm you have to transmit everywhere from a single source.
I don't think these problems are insurmountable, we already do engineering on this scale, it would just be all in one place rather than spread throughout the country (like having every oil refinery in the US in one place rather than spread throughout).
Run superconducting cable to major distribution nodes could help with that, but cooling superconductors with liquid nitrogen takes part of the savings of energy and nitrogen isn't a renewable resource either.
All that said, I'm still a fan of solar and I think eventually we will get there, the sun's giving us all the energy we need. I just don't think we can replace coal fast enough with it and that we'll need an intermittent step of nuclear.