Yes I guess this is the same calculations as for my furnice. Test institutes are talking about 80-90% efficiency. Losses is imperfect burning and heat going out of the chimney. All energy that take the form of heat can be taken into account for as the main purpose is to warm the house. If, for once, losses in the form of heat is good keeping a 1/6 ratio between electricity and heat generation is easy as you can use the excess electricity (diff from your usage) to generate heat again. This of cource get troublesome when your house is warm enough... Another thought... Could a striling engine be used on the exhaust gases from a furnice to produce electricity and raise the furnice efficiency. /Ake -----Ursprungligt meddelande----- Fr=E5n: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]F=F6r Richard.Prosser@POWERWARE.COM Skickat: den 7 april 2004 00:46 Till: PICLIST@MITVMA.MIT.EDU =C4mne: Re: [OT]: Superb low temperature differential Stirling Engine I think they are regarding all mechanical losses as heat, which is then used for local heating, rather than producing electricity. On this basis, the only losses are the burner losses, which may well be 90% efficient I guess although I would have thought that 10% wastage going up a flue would be about as good as you could ever expect. (Not to mention unburnt fulel particles). I'm no expert here though. This does seem to infer that the device is positioned so that any local heating is of benifit to the user and is not just heating up waste space in a basement or garage or garden shed etc. Also, bear in mind that these units are somewhat expensive and that they are still in pilot stage - there may be reliability issues or service costs to be added to the final equation. Richard P I do not belive the 90 percent efficiency claimed by them. It cannot be that good, due to the fact that there has to be major leakage (heat) between the hot side and the cold side of the piston. Even if the 'block' is plastic, there will still be a major heat loss. A burner (heat source) can be 90 percent efficient, but any moving parts are going to shoot their claimed efficiency specs down. If the efficiency was that good, they would be all over the place, especially in off the grid and isolated locations. Heat (as a byproduct) can be used to make cold air as well-so the unit could heat in winter and cool in summer. Flame suit on, fire away. Art At 04:34 PM 4/6/04, you wrote: >http://www.whispergen.com/ >Trials appear to be underway but I haven'r heard much about them for a year >or so. >Richard P > > > > > >Do you have som epointer for more info about "Whispergen"? > >/Ake > >-----Ursprungligt meddelande----- >Fr=E5n: pic microcontroller discussion list >[mailto:PICLIST@MITVMA.MIT.EDU]F=F6r Richard.Prosser@POWERWARE.COM >Skickat: den 6 april 2004 22:07 >Till: PICLIST@MITVMA.MIT.EDU >=C4mne: [OT:] Superb low temperature differential Stirling Engine > > >[Topic Added] >I think this is the philosophy behind the "Whispergen" stirling >engines. - >Electricity is produced as a by-product of home heating. >RP > > > >Sorry 137 KWh a day is the correct value. > >-----Ursprungligt meddelande----- >Fr=E5n: pic microcontroller discussion list >[mailto:PICLIST@MITVMA.MIT.EDU]F=F6r Ake Hedman >Skickat: den 6 april 2004 11:02 >Till: PICLIST@MITVMA.MIT.EDU >=C4mne: SV: SV: ] Superb low temperature differential Stirling Engine > > >But if you use a higher temp difference. > >In my case I warm the house with pellets and say I have a stirling >engine in a pre stage to my heater. pellets burn with a temp around 1200 >C > >1200 + 273 - 300 / 1475 =3D 79% 1/3 =3D> 27% This goes to the electric >generator. > >I guess the losses are in heat so it can be used it to warm the house. > >I use about 1000 kg of pellets a week for warming in the winter ( big >house ). The total energy used a day is thus 1000 * 4.8kWh =3D 4800 KWh >Say I have 20% efficiency for the electivity generator I can take out >960 KWh a day in electric energy!!! and have the rest left to warm the >house. > >Do I have a fault in my thinking here? > > > > > > > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics