> I guess I would need a spreadsheet that shows operating cost and heat and > electricity output vs. the same output from a standard gas heater and the > local utility company. Or some quick math... Power generation efficiency is 20%. Is one BTU/joule/kwh/insert-your- favorite-flavor-of-energy-unit-here of electricity more or less expensive than 5 BTUs of natural gas? Natural gas is usually measured in therms... 1 therm = 100,000 BTU = 29.3 kwh Google says... http://www.apta.com/research/info/online/documents/fuelsurvy.pdf Outdated, for 1999-2000, but since both prices are for that time frame, something like apples and apples... $.071/kwh for electricity, $.6989/therm for natural gas = $.024/kwh 20% of the natural gas energy going into the device becomes electricity, and if I'm reading it right, 65% of the remainder is turned into home heat. So, 1 kwh of delivered electricity costs 12 cents (requiring 5 kwh of gas), but of the remaining 4 kwh of energy, 2.6 kwh go into your house as heat. Subtract that 2.6 kwh = 6.24 cents from the 12 cents, since you would pay it for home heating anyway, and you are left with 5.76 cents per kwh. If you max the sucker out, pulling its full 1 kw all the time, you stand to save about $9.65 a month. During the winter, when your furnace is on and this contraption can take up some of the slack of heating the house. If it's 65% of overall is captured as heat, then subtract 3.25 kwh = 7.8 cents from the 12 cents, leaving 4.2 cents per kwh of electricity and bringing the savings to $20.88 per month. More promising. IF it's fairly cheap, there may be a market in placing several of these at different spots throughout a largish house, replacing one large, expensive furnace with several small, cheap ones, which also offset their cost by putting some power back into the house. During the summer, of course, you'd either need to put it outside or run an additional air conditioner to offset its heat output. Mike H. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist