[Jhoffa_]

Along these same lines, I once saw a guy with a big frensel lens (I think that's what it was, sort of opaque looking and had grooves in it. Like what you would see in an old overhead projector maybe.) melt concrete..

If you could focus several of those, could you boil enough water with them to run a small steam turbine?

Hey, it melted concrete..

?

[Jhoffa_]

Be even neater if you could capture and condense the steam, recycle it.

Add some type of X-Y positioning device run with stepper motors and phototransistors, or a lookup table for position or something so it could track the sun as it progressed across the sky.

[RLK]

You'd probably have a good shot at running a small steam turbine or steam engine.

[boris]

The problem is, you get 1 kilowatt per square meter at the surface of Earth with a perfectly clear sky, at the equator, at high noon.

Solar cells are about 30% efficient, and it is night-time about 50% of the time, so you now have 150 watts per square meter. Since you need to plan for night-time operation, maintenance, clouds, bird droppings, the actual number is more like 100 watts per square meter.

This is a poor use of real estate. To power California--which uses 40,000 megawatts, 24/7, you'd need at least 150 square miles of solar panels. If solar cells cost one cent per square centimeter, this works out to (as I recall) something like $30 billion. This also ignores the utter waste of replacing our existing infrastructure with solar cells.

Yes, you can get a lot of heat if you concentrate the rays of the sun. But energy is energy; you simply cannot reduce the total collecting area you need. If your concentrator gives you "100 suns" you'll need 100x less solar cell area...but the concentrator (big fresnel lenses/parabolic reflectors, etc) will still require 150 square miles for California alone. Can you imagine 150 square miles of fresnel lenses? Or 150 square miles of aluminum mirrors?...

--Boris