Future energy sources

August 9, 2005 1:10 PM

It's obvious that none of the current energy producing methods we have has enough power to make say space travel affordable and fast for everyone. So no Star Wars / Jetsons type flying spaceships and cars for now. But are there any up and coming energy sources that will be able to do this?

Also when the future energy source is cheap, how will we avoid overheating the planet?

posted by riffola to science & nature (8 comments total)

Says who? Nuclear power is immense, it's just so immense it is really dangerous!

If this energy source of the future is so cheap, why don't we just use it to shoot the waste into space or the sun?

What if improved solar is the energy source, won't we then need to worry about cooling the earth since the existing warming solar rays will be converted into other forms of energy?
posted by Pollomacho at 1:33 PM on August 9, 2005

Shooting waste into space costs energy -- lots of it. Even shooting it into the sun costs a lot of energy, since you have to slow it down a lot in order to have it fall out of our orbit.

Nuclear fusion's next Grand Hope, the ITER reactor, will be built in France, starting soon. It's a research reactor, though, so may not even work.

For really low power demands, perhaps zero-point energy (e.g. for nanobot power)

The issue of heating the planet isn't as much of a problem as polluting it. Sunlight drops about 2.4kW per square foot on the earth's surface, most of which is reflected or radiated right back out again. Global warming is mostly due to pollution, not our actual use of energy.

Besides, any "future energy tech" would presumably be accompanied by enormous increases in efficiency, thereby leading to much less waste heat!
posted by 5MeoCMP at 1:54 PM on August 9, 2005

Pollomacho: Rockets loaded with radioactive waste are also called "dirty bombs" and considered unsafe. If the sunlight is converted into other energy forms, such as electrical power, it eventually turns into heat when we use it. There's no need to worry about the earth getting too cold.

Look here for a bit of insight and ranting on the topic.
posted by springload at 2:10 PM on August 9, 2005

*But are there any up and coming energy
*sources that will be able to do this?

If you start from orbit, space travel is not that hard. It seems hard to us because we are sitting at the bottom of a big gravity well and it's a lot of work to climb out every time we want to go somewhere. Give people a beanstalk or something to get up there and the rest of it is doable now.

*when the future energy source is cheap,
*how will we avoid overheating the planet?

Orbital shades. Or tinker with the chemistry of the atmosphere. Or albedo management down here. Make everybody wear reflectorized coolie hats. ten billion x .5 meters of hat each = lots of cooling)

*If this energy source of the future is so cheap, why
*don't we just use it to shoot the waste into space
*or the sun?

Not really an efficient idea. It would be like hiring a chaufer to come around with a Cadillac every time you wanted to throw out a tissue.

*if improved solar is the energy source, won't we
*then need to worry about cooling the earth since the
*existing warming solar rays will be converted into other
*forms of energy?

No. Whenever you use energy to do work, the energy eventually winds up as heat. There was this guy Newton had some stuff to say about that. If you get the energy from orbital satellites, and they collect light that would have missed the Earth, then you will warm the Earth.
posted by Ken McE at 3:45 PM on August 9, 2005

The energy source of the future is either fusion or massive amounts of space based solar (once we have the space elevator up.)
posted by TheOnlyCoolTim at 5:02 PM on August 9, 2005

Sunlight drops about 2.4kW per square foot on the earth's surface

actually, in space the total radiant energy flux from the sun is around 1400 watts per squre meter. around a third of this is absorbed or reflected in the atmosphere, so that drops to around 1000 watts per square meter.

averaging over variations due to day/night and yearly changes, the average solar intensity at the surface is, in exceptionally sunny areas like the sahara desert or the australian outback, only around 300 W/m^2. in units of square feet, this works out to around 40 W per square foot.

i am pointing this out not to be a nitpicker (well, not entirely), but to show that any attempt at economically harvesting solar energy will require a high conversion efficiency and lots of surface area, which means high capital costs.
posted by sergeant sandwich at 5:02 PM on August 9, 2005

objects at room temperature emit thermal radiation in the infrared region of the spectrum. this guy is working on an interesting new approach to collecting this energy and using it for low-power applications like small electronics.

it's pretty interesting, actually. the comment on zero-point energy made me think of it.
posted by sergeant sandwich at 5:14 PM on August 9, 2005

Sergent's correct. Planet-based solar harvesting won't really be effective... ever. What might someday be effective is orbital harvesting of power... you could easily launch a couple of satellites up into a high enough orbit to provide power 24/7. Then your problem is transmitting it, which you can do with microwaves down to the planet's surface ... or better yet, transmit it to a space elevator and then down a wire.

Unfortunately, that would require a space-based construction ability (because you wouldn't be able to launch all that hardware in a way that would put itself together that easily, a space elevator, and would also require that we've finished perfecting the power transmission technology and tested it in orbit. All of the things above would require that we have much cheaper surface to orbit transport than we do now...
posted by SpecialK at 7:59 PM on August 9, 2005