Environmental Engineering Reference
In-Depth Information
1993, Japan started a major 28 year, $11 billion hydrogen research pro-
gram called New Sunshine. It surpassed Germany's hydrogen program
to become the biggest program at that time. The basic hydrogen research
included work on the metal-hydride storage systems that are used in Toy-
ota's fuel cells. German government support has declined since reunifica-
tion. About $12 million was budgeted in 1995.
Direct hydrogen research has involved tests with fuel tanks pressur-
ized at 5,000 pounds per square inch, which could provide a reasonable
range without a reformer. Carbon-fiber composites which have been used
in lightweight car bodies could also be used but they are very expensive.
The hydrogen fuel tank needs to provide a range of about 350 miles with-
out using excessive space. A light fuel cell car with a 5,000-psi carbon-fiber
tank might be able to travel almost 225 miles before needing to be refu-
eled. Direct hydrogen storage is getting close to an acceptable range, but
there could be a liquid fuel stage. This would allow the use of the existing
gasoline refueling infrastructure that cost hundreds of billions to build.
Hydrogen infrastructure will depend on where the hydrogen is pro-
duced and what form it is stored. The major choices are onboard hydrogen
production, centralized production, and production at fueling stations.
Reforming either methanol or gasoline into hydrogen onboard a vehicle
is likely to be less efficient than stationary reforming. Onboard reformers
produce less pure hydrogen, which reduces the fuel cell's efficiency. The
overall efficiency for gasoline and methanol fuel cell vehicles is likely to be
much lower than for hydrogen fuel cell vehicles. The onboard reforming
of gasoline to hydrogen produces modest emission benefits.
Onboard gasoline reforming could serve as an interim step and ac-
celerate the commercialization of PEM fuel cells. It does not require a hy-
drogen infrastructure. Onboard methanol reformers are likely to be even
less efficient than gasoline reformers. For the immediate future, increases
in methanol production are likely to come from overseas natural gas.
Any significant use of methanol as a transportation fuel would require
Search WWH ::

Custom Search