ewh@druky.UUCP (HarkinsEW) (03/29/85)
re: hydrogen; the point was madee by Jim Wall, and rightfully so, that solar is a very diffuse resource. That is exactly why the ocean (remember it's ~2/3 of the earth's surface) is such a good collector. That said, how do get from that stored energy to hydrogen? They call it OTEC, Ocean Thermal Energy Conversion, which essentially uses the difference in temperature from the surface (in the 30-35 degree lat. toward the equator, ie, more or less tropical) to something like 200 feet down, to drive a Rankine cycle "engine". Simplistically, you use freon or something similar, in a heat exhanger type device; the surface heat vaporizes the freon, which runs the engine (this can drive a generator, which gives you all that "free" electricity for breaking down water into hydrogen and oxygen (not oxymorons, !! 8-) ); once the vapor is thru that engine system, it is piped (still under some inherent pressure recall) down to where the ocean temp is cold enough to liquify the vapor back into liquid; it is then pumped back up to the top to repeat the cycle. It turns out of course, that there is an economy of scale factor since all this hardware is not free, and some engineering problems related to scaling (as in barnacles), and figuring out how to make that whole thing resist the ocean environment. What to do with the hydrogen? Once made it can be liquified and shipped in cryogenic tankers to the port of choice for car or powerplant use. It also can be used to bind nitrogen from the air into ammonia for fertilizer... Other factors: there is some ecological spinoff in the warmer water produced by the mixing that can be used to promote "shrimp farming." This can be viewed negatively, but it would obviously take very large numbers of these plants to make a significant ocean impact overall. As you may infer, i'm sold on this concept; there is currently a large scale pilot project going on under DOE sponsorship in Hawaii, so maybe the folks out at UH would like to comment. ernie harkins