Environmental Engineering Reference
In-Depth Information
board hydrogen tanks.
Fuel cell research has become a major international trend with many
engineers working on this technology worldwide. Germany already has
enough methanol production to fuel 100,000 cars and worldwide, there is
enough methanol for 2 million cars.
DaimlerChrysler renewed its interest in liquid hydrogen, and that
was the fuel in NECAR IV that appeared in 1999. NECAR IV was among
the first drivable, zero-emission, fuel cell cars in the United States along
with the Ford and GM fuel cell prototypes. It was a major advance over
NECAR III, whose cell and reformer took up all the passenger space. NE-
CAR IV was still heavy and slower to accelerate than Ford's P2000 fuel cell
car, but it had room for five, with a 40% power increase over the earlier
version, a higher top speed of 90 miles per hour and a range of 280 miles.
BMW will offer a 7 series version which will operate on hydrogen
and gasoline. BMW and DaimlerChrysler are in partnerships with the
German company Linde, a builder of liquid hydrogen refueling stations.
But handling liquid hydrogen is difficult, since hydrogen reaches a liq-
uid state at minus 400°F, the cold fuel can cause serious damage to skin.
Liquid hydrogen stations could be run by robots. There already is such a
station in Munich. Making liquid hydrogen work as an auto fuel requires
some new techniques, like attaching the tank to the car with a magnetic
holder to isolate it from thermal convection. A liquid hydrogen tank could
be a little larger than a gasoline tank and it would offer a comparable
range. A superinsulated tank can keep liquid hydrogen cold for weeks,
but after a time it would warm up and return to a gaseous state, requiring
that it be vented from the tank. This hydrogen gas can be recaptured and
reused but this is one the practical challenges being worked on.
HYDRIDE STORAGE
The developmental efforts and formidable challenges of hydrogen
delivery and storage are being addressed. All fuel cells need hydrogen
to operate, but a low cost, safe and efficient storage system has been elu-
sive. Until recently, there were only two ways of storing pure hydrogen
on vehicles as a cryogenic liquid or pressurized gas. Practical cryogenics
is a wily task and pressurization can be bulky and potentially dangerous.
Gasoline or methanol teamed with an onboard reformer to extract the hy-
drogen adds substantial costs and complexity to a vehicle, while voiding
Search WWH ::




Custom Search