earthquakes: a usable power source ?

[science_man_88]

This earthquake and aftershocks could of supplied quite a bit of energy. after all they are all over 4.0 at last check and 250+ in fact it looks to be about 357 so far.

[Uncwilly]

Originally Posted by xilman

Send the energy back to Earth by any of a number of mechanisms.

IIRC, to make orbital PV energy practical. the receiving stations would be extremely large and pose significant problems of their own. (Like cooking the animals and plants under them.)

[Christenson]

Originally Posted by xilman

Again, too high a likelihood of unacceptable collateral damage.

That's precisely why I think national capitals should be the landing spots -- this maximises useful damage and minimizes collateral damage!

More seriously, how would you get that energy down from orbit, assuming you *did* care about the ground underneath? Microwaves? IR Lasers? As chemicals, say, bottles of liquid hydrogen, with the idea of minimizing environmental impact if a landing went badly? Or would it make sense to simply aim solar radiation with mirrors at your favorite spot in the Mojave desert?

[xilman]

Originally Posted by Christenson

That's precisely why I think national capitals should be the landing spots -- this maximises useful damage and minimizes collateral damage!

More seriously, how would you get that energy down from orbit, assuming you *did* care about the ground underneath? Microwaves? IR Lasers? As chemicals, say, bottles of liquid hydrogen, with the idea of minimizing environmental impact if a landing went badly? Or would it make sense to simply aim solar radiation with mirrors at your favorite spot in the Mojave desert?

As I mentioned earlier, microwave beams are the classical solution. EM radiation at other wavelengths would work, as you note, as long as the Earth's atmosphere is transparent.

Chemical energy would also work well, but liquid hydrogen is probably a non-starter. It's dangerous stuff if it leaks into an oxygen-containing atmosphere, especially hard to transport without leakage and relatively low energy density for a chemical fuel. The real killer, though, is that there isn't very much hydrogen readily available on the moon. What is present in large quantities are metals, silicon and oxygen. The solar cells would be primarily silicon extracted from rock. The oxygen could either be vented, which sounds a bit of a waste, or stored for later use. The metals, especially aluminium, could be powdered and shipped back to earth in containers. Back here, burn the Al in atmospheric oxygen and use the heat produced in classical power generators. Needless to say, we wouldn't continue to produce Al down here by electrolysis!


Paul

[Christenson]

So, the problem is that if I want hydrogen from the moon, I need to produce it in a particle acceleratore (for gold, that's reputed to run about $3K/ounce, 20 or more years ago).

The reason I was thinking of hydrogen is that the byproducts are relatively benign (water) when burned in a 20% oxygen atmosphere.... while we are solving the worlds great problems, what abundant element on the moon could I use to lock up carbon when I "burn" it to make chemical energy? (also, if we are farming energy on the moon, can we simply direct a lot of sunlight to a small area on earth, since mirrors are reasonably efficient, though I suspect that the bearings might kill us as the lubricant evaporates in the hard vacuum?, or is it likely to be a on just the right scale to cause major weather disturbances? -- this kind of impact is probably a killer, I think I'd rather land small meteors of finely divided or possibly solid aluminum..) (Of course, we could also move GIMPS to the moon, since it just needs electricity and some computer chips! :) )


Oh, and science man88, if you are still reading this, I have a homework problem for you.....

Take a ton of sand, in 50 pound bags, raise it up six feet, and extract the energy over the next week in a useful form. You have in miniature the problem of extracting the energy in the form it comes before an earthquake strikes......

[CRGreathouse]

Originally Posted by Christenson

Take a ton of sand, in 50 pound bags, raise it up six feet, and extract the energy over the next week in a useful form. You have in miniature the problem of extracting the energy in the form it comes before an earthquake strikes......

That sounds far easier than extracting usable energy from an earthquake.

[Christenson]

Originally Posted by CRGreathouse

That sounds far easier than extracting usable energy from an earthquake.

It is...but the easy problem is an excellent analogue for the hard problem for those who want to work on solutions or think they might have a solution.

As I said earlier, *small* quantities of energy are easily extracted from earthquakes when they happen. Making the amount large, and spreading it over the decades between earthquakes, that's hard!

[CRGreathouse]

Originally Posted by Christenson

As I said earlier, *small* quantities of energy are easily extracted from earthquakes when they happen. Making the amount large, and spreading it over the decades between earthquakes, that's hard!

Even without spreading it out that would be a remarkable feat.

[Oddball]

Originally Posted by science_man_88

Think about it if a 1.0 produces 1 joule in 1 second = 1 watt. With a logarithmic scale a 8.9 over that same time could produce as much as about 79 megawatts.

It's logarithmic, but an increase in magnitude of 1.0 results in a quake that's 31.6 times stronger, not 10 times stronger. So, an 8.9 quake won't produce 79 megawatts (10^(8.9-1)); it'll yield a lot more power.

Of course, getting usable energy from an earthquake is a whole different issue.

[science_man_88]

Originally Posted by Oddball

It's logarithmic, but an increase in magnitude of 1.0 results in a quake that's 31.6 times stronger, not 10 times stronger. So, an 8.9 quake won't produce 79 megawatts (10^(8.9-1)); it'll yield a lot more power.

Of course, getting usable energy from an earthquake is a whole different issue.

I was thinking the original base 10 version sorry.

[CRGreathouse]

Originally Posted by science_man_88

I was thinking the original base 10 version sorry.

It is base 10 -- in amplitude. But energy varies as the 3/2 power of amplitude, thus the