From the Oct/Nov 2004 issue of Fuel Cell Magazine, a press release about the 2005 Honda FCX hydrogen fuel-cell powered vehicle:
"With an EPA city/highway rating of 62/51 mpkg (57 mpkg combined) . . . the hydrogen powered FCX delivers nearly a 20 percent improvement in fuel efficiency . . .." and "In terms of energy efficiency, one mile per kilogram (mpkg) of hydrogen is almost equivalent to one mile per gallon (mpg) of gasoline." I don't know whether to be happy to they are using kilograms rather than pounds to measure the hydrogen, or unhappy with the compounding of colloquial and metric units. There is no indication of the form of the hydrogen, but in a different article about a Ford research vehicle using hydrogen internal combustion, the hydrogen is specifically mentioned as gaseous, and ". . . the three tanks accommodate 119 liters, which equates [at 350 bar] to 2.75 kg of hydrogen and provides a range of about 200 km." (which equates to about 45 mpkg) It's been many years since I studied physics, but it seems to me it would take a non-trivial amount of energy just to compress hydrogen to 350 bar (35 MPa, about 5000 psi), and since it goes through a pressure regulator (down to 5.5 bar) before getting to the manifold, essentially none of that would be recovered as useful work. Jim Elwell Jim Elwell [EMAIL PROTECTED] 801-466-8770 www.qsicorp.com
