Post by thread:[EE:] Fuel Cells - direct Methanol cells becoming

So...you're on the fuelcellstore.com newsletter too, eh Russell? :) Any info about available Stirling Engines that can be purchased now? Incidentally, the http://www.stirlingengine.com/ is a pretty cool site with a really nice overview of Stirling engines in the FAQ section. Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams On Fri, 9 Jul 2004 12:32:18 +1200, Russell McMahon <.....apptechKILLspam@spam@paradise.net.nz> wrote: {Quote hidden}> Methanol fuel cells are starting to get useful. > A way to go yet though I think. > Certainly worth comparing with Hydrogen fuel cells. > > $US3500. 25 watt continuous output. 1.5l Methanol / kWh. > 2.2 kg. Toolbox size (dimensions given on site are wrong) > > http://www.fuelcellstore.com/cgi-bin/fuelweb/view=Item/cat=/product=644 > > I suspect that a decent Stirling engine design would give it a good run for > it's money. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> So...you're on the fuelcellstore.com newsletter too, eh Russell? :) Aye. Isn't everyone :-) > Any info about available Stirling Engines that can be purchased now? Not at that small size unless you are military/aerospace and / or well heeled. But http://www.whispergen.com is a real NZ company making real co generation Stirling Engine systems that are in use worldwide. Not cheap, but users say they are cost effective overall compared with alternatives. And $ per watt is far better than for those Methanol fuel cells. Just can't see myself carrying one on my back :-) !!! RM -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

Russell, On Fri, 9 Jul 2004 12:32:18 +1200, Russell McMahon wrote: > Methanol fuel cells are starting to get useful. > A way to go yet though I think. > Certainly worth comparing with Hydrogen fuel cells. > > $US3500. 25 watt continuous output. 1.5l Methanol / kWh. And at $30 for 2.5l of Methanol, I make that $18/kWh... a *long* way to go before it becomes affordable, IMHO! I'm all for alternative energy sources, but not when they're a couple of orders of magnitude more expensive than those in place... Cheers, Howard Winter St.Albans, England -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> > $US3500. 25 watt continuous output. 1.5l Methanol / > kWh. > > And at $30 for 2.5l of Methanol, I make that $18/kWh... > a *long* way to go before it becomes affordable, IMHO! > > I'm all for alternative energy sources, but not when > they're a couple of orders of magnitude more expensive > than those in place... The Methanol doesn't have to cost that much of course. Quite why anyone would pay their prices I don't know. While there may be a rigid purity spec I suspect it's not THAT rigid. Such devices, so far, are targeted at fairly niche applications. I have a "blue sky" niche application that would bear that sort of cost if it ever actually happened - but so far the fuel cells are largely big boys (and girls) toys. For my application I suspect that what is effectively a Stirling engine will fill the need better. (I say "effectively" as any device which uses external heating and operates on the Carnot cycle is effectively a Stirling engine, even if it doesn't look wholly like the normal idea of one.) FWIW My spec is something like: Up to 100 watts continuous max electrical output for 5 days. More peak power would be nice. Waste heat not a problem. Combustion by-products if present not a problem. "Battery"/Engine whatever mass as low as possible. Preferably under 5 kg. Fuel mass required as low as possible. 100w x 24 hrs x 5 days = 12 kWh. That's about the energy in 1kg of LPG !!! If you can get 20% electrical efficiency out, that's 5 kg of "fuel". If you can do the above you have a 10 kg unit. Doing that with Lithium batteries at say 250 Wh/kg would weigh about 12,000/250 = 48 kg. And the above system could be extended to double the time by adding another 5kg of fuel. Is it doable with a Stirling? Carnot efficiency at 300C hot side is about 50%. At 600C it's 66% or so To get 20% delivered you need to get about 1/3 of Carnot efficiency which is "a bit of an ask" but arguably not undoable. But with any luck the fuel cells will come storming past some time soon. My battery file notes say XL space systems projected Peroxide-Aluminium fuel cells to have a capacity of 280 Wh/lb or about 600 Wh/kg - which is still far short of the Stirling target above. Quoted energy densities for Zinc-Air batteries are around 200 Wh/kg. Suggested energy densities for leading versions approach that for Al-Peroxide but therefore fall far short of the total energy content of many liquid fuels. Good, possibly useful, Zinc-Air paper (year 2000) "The status of primary Zinc Air battery technology for application in handheld electronic products." http://www.huret.com/archivesx/PBD-2000/AER-2000.pdf Interesting but probably not useful 1995 paper on Zinc - Air for LARGE commercial uses with mechanical recharging and zinc regeneration. http://www.electric-fuel.com/evtech/papers/duisburg.pdf Russell McMahon -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads