Soup posted a map this morning of the land area necessary to power the world with solar panels. If there were collectors on some small-looking percentage of the Earth’s land mass, it would be enough. Some researchers have calculated world roof-top area, and it’s close to the right number.
I was looking through the responses and noticed that someone reblogged and asked why we weren’t doing this. It is a good question.
I am an energy scientist—more specifically I am an electrochemist, which means I study the conversion from electricity to mass. This is what happens in batteries, fuel cells, solar cells, etc.
World energy use (2001 numbers) is 13.2 TW. TW = tera-watt, and means a trillion watts. (The USA was 3.2 TW of that, or about 25%.)
These are watts just like in a light bulb. A watt is a measure of energy required per time. So if you need more electricity faster, then the watts go up.
Here are the numbers for energy you can get out of many common renewable energy sources:
- Hydro-electric: 1.5 TW (how many rivers are there?)
- Geo-thermal: 11 TW (hard to get the energy though)
- Wind: 2-4 TW (where is it windy enough?)
- Biomass: ~5 TW (water and land will limit)
- Solar: 120,000 TW
So that shows why solar power has such potential. Massive amounts of sunlight hit the Earth every day, the sun is free, the sun is plentiful, and the sun will not go out (soon anyway).
i.e. There is a shitload of sun.
Plants are geniuses, and photosynthesis makes about 90 TW all the time. They do it all by themselves. How can we do that?
So, why do we not do that already? Here is how much it costs to make energy in several different ways (2002 numbers):
- Coal: 1-4 cents per kW-hr
- Gas: 2.3-5
- Oil: 6-8
- Wind: 5-7
- Nuclear: 6-7
- Solar: 25-50
That’s why. Production, operation, and maintenance of solar cells needs to become about ten times cheaper. This will happen both by research for new designs, and by experience gained operating the solar cell systems we already use.
If you wonder why we still use coal, and why solar is still only something for people to put on their roofs, those cents-per-kW-hr numbers are why. If someone asked you to pay for 100,000 kW-hr (for example), you would use coal, too.
I got the numbers given here from a lecture by Nate Lewis, a chemist at CalTech. A streaming video of him giving the lecture is here, and very good if you care about energy.
I have this conversation a lot.
other person: Are you working this weekend?
me: nope! exciting!
other person: GREAT! you can [insert thing that will probably take entire day] with me!
me: well, I have these other plans so I can’t.
other person: I thought you weren’t working!?
why. Why is not working = free entirely with no other plans whatsoever ?
it happens often. I don’t understand. Is it me? that’s weird right?