Environmental Engineering Reference
In-Depth Information
If fuel cell cars run on gasoline, there is minimum disruption, but
many predict that methanol will serve as a bridge to direct hydrogen.
Early fuel cell cars may run on methanol, but rapid advances in direct-hy-
drogen storage and production could bypass any liquid fuel phase.
When gasoline or methane is used as a source of hydrogen, the hy-
drogen is separated from the hydrocarbon molecules using partial oxi-
dation and autothermal reformers. Cost is an issue for onboard gasoline
reformers and another is that the high temperature at which they operate
does not allow for rapid starting. The reforming process also involves a
loss of about 20% of the energy in the gasoline. In 2003, Nuvera Fuel Cells
developed a 75-kW gasoline reformer. It has an 80% efficiency but requires
more than a minute to start. Nuvera has been working to get this down to
30 seconds and believes that the reformer could eventually sell for about
Gasoline fuel cell vehicles (FCVs) could be an interim step. Their
main advantage is the use of an available fuel. An affordable gasoline re-
former could allow a market for fuel cell vehicles without a hydrogen in-
Methanol has several advantages for powering fuel cell vehicles.
A study for the California Fuel Cell Project (CAFCP) pointed out metha-
nol's availability without new infrastructure, high hydrogen-carrying ca-
pacity and the ability to be stored, delivered, and carried onboard with-
out pressurization. Methanol reformers operate at lower temperatures
(250°C-350°C), so they are more practical than onboard gasoline reform-
ers. Methanol reformers could also be used at fueling stations to generate
forecourt hydrogen.
Direct methanol fuel cells (DMFCs) can run on methanol without a
reformer. But, practical, affordable DMFCs for cars and trucks may still be
years away.
Methanol has been used to make MTBE, a gasoline additive now be-
ing phased out because of environmental concerns such as groundwater
contamination. Although methanol exists in nature and degrades quickly,
MTBE is a complex, compound that exhibits little degradation once re-
leased into the environment.
If there were to be a dramatic increase in U.S. methanol use, most
of the supply would have to be imported. Biomass-generated methanol
might be economical in the long term, but there is a significant amount
of so-called stranded natural gas in areas around the globe that could be
converted to methanol and shipped by tanker at relatively low cost. There
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