Cheap Thermo-Acoustic Solar Power ($0.36/w) Thermo-Acoustic
http://www.io.com/%7Efrg/history.htm The MicroTAC was born in 1994. Theoretical thermal-electric conversion efficiency is very good (30% - 40%). The design and fabrication are well within common machine shop/Lab capabilities. A production cost quote from a major manufacturing plant came in at US $7.16 for a twenty Watt device ($0.36/Watt) in quanties of 100,000. That includes the cost of tooling. Larger production runs would amortize tooling cost even more.
http://www.io.com/~frg/ Powered by Solar Energy or Waste Heat: When powered by solar radiation or waste exhaust heat from other systems, the TAC produces power with no polluting gaseous emissions.
Cost of capitalized equipment: TAC < $0.25/Watt (W) MEMS-TAR < $0.10/W
http://www.americanscientist.org/template/AssetDetail/assetid/21006/page/1 The Power of Sound Sound waves in "thermoacoustic" engines and refrigerators can replace the pistons and cranks that are typically built into such machinery
PATENTS: Patent 4,677,825 Thermomotor Patent 4,779,421 Hot gas engine Patent 5,177,968 Radial hot gas engine
Best of all, the heat of expanding gases in electrolysers can fed back into the power generators.