Thanks Arthur, this is an interesting bit of digging, I'll pass it around for others to read.
On Thu, 9 Oct 2003 06:56:16 -0700, you wrote: >It has often been raised in this forum a comparison of fuel cells >versus batteries for operating cars. But I've seen no hard >documented data. So I decided to look some up. > >The Electric Storage Association has a website ><http://www.electricitystorage.org> that describes various energy >storage technologies and their efficiencies. Under Li-Ion ><http://www.electricitystorage.org/tech/technologies_technologies_liion.htm>, >they cite an efficiency rate of nearly 100%. Unfortunately, they do >not cover the efficiency of NiMH nor of hydrogen. > >The Toyota current Fuel Cell prototype FCHV-4 ><http://www.toyota.co.jp/en/tech/environment/fchv/fchv12.html> has a >well-to-tank efficiency of 58% (if the hydrogen is produced from >natural gas) and tank-to-wheel efficiency of 50% (with hybrid >technology) for an overall efficiency of 29%. Toyota's ideal fuel >cell vehicle has a well-to-tank efficiency of 70% and a tank-to-wheel >efficiency of 60% for an overall efficiency of 42%. They observe >that the well-to-tank efficiency of gasoline is 88%. The Prius 2003 >had a tank-to-wheel efficiency of 32%, for an overall well-to-wheel >efficiency of 28%. The Prius 2004 has a tank-to-wheel efficiency of >37% (2004_Prius_Tech_Pres_08-22-03.ppt). Under the well-to-tank >efficiency of 88% (quoted on Toyota Fuel Cell website), the Prius >2004 overall efficiency is 33%. Under the well-to-tank efficiency of >79% (quoted in Prius presentation), the Prius 2004 overall efficiency >is 29%, the same as the overall efficiency of the commercial fuel >cell vehicle (presumably Toyota FCHV-4) cited at 29% in both places. > >Some interesting comparison charts can be found at ><http://www.worldenergy.org/wec-geis/global/downloads/NZConf/2_08.pdf>. > >A detailed article comparing well-to-wheel efficiency is at ><http://www.memagazine.org/mepower03/gauging/gauging.html>. They >quote battery + all electric as having a "tank"-to-wheel efficiency >of only 44% (it is tied for first place with 3 others on their chart). > >The 1998 Toyota RAV4-EV was rated ><http://avt.inel.gov/fsev/rav4/toyrav98.pdf> at 245 Wh/mile (from >battery) and 432 Wh-AC/mile (from grid). That would make >"tank"-to-wheel efficiency at 57%. [At 10 cents/Wh, they quote 4.32 >cents/mile.] Note that the 1998 Toyota RAV4-EV had a *conductive* >charger, so it was more efficient than the later *inductive* charger. >Note that this "tank"-to-wheel efficiency of 57% is comparable to >Toyota's 60% tank-to- > >So if the ultimate source of energy is electricity, then a battery >electric car is the most efficient and beats hydrogen hands down. >(If the electricity is locally generated, then the "well"-to-"tank" >efficiency would be 100%. Otherwise, there are decreases that need >to be made for ) > >On the other hand, if the ultimate source of energy is natural gas, >then combined heat and power systems can be over 75% efficient (see ><http://www.aceee.org/energy/nrgeffbrief.pdf> slide 4). For example, ><http://www.oceta.on.ca/profiles/admic/admic_tech.html> generates >heat with 55% efficiency and electricity with only 30% efficiency. >(That's also the figure quoted in ><http://www.naturalgas.com/consumer/>.) In that case, well-to-wheel >efficiency of the 1998 Toyota RAV4-EV is 30% times 57% or only 17%, >while the Toyota FCHV-4 is at 29%. > >Conclusions: > >If electricity is produced from renewable sources (solar, wind, and >even hydro), then there is zero air pollution for battery electric >vehicles, and they have the highest efficiency of 57%. > >If the energy source is natural gas (and note that usage is eclipsing >supply), then Toyota's ideal fuel cell hybrid vehicle would be 42%. > >If the energy source is oil, then the Prius 2004 has a well-to-wheel >efficiency of 29-33%. ------------------------ Yahoo! Groups Sponsor ---------------------~--> Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
