Hydrogen's heyday: green machines leave the lab and hit the highway

Automotive Industries, Jan, 2005 by Don Sherman

Powering your car with water is a fantasy that ranks with turning tin to gold. But the next best thing--[H.sub.2]O without the O--isn't so farfetched.

Last month, California Governor Arnold Schwarzenegger beamed a radiant smile to news cameras while pumping his Hummer's fuel tank full of hydrogen ([H.sub.2]) at a new Los Angeles International Airport station. "What?!," you say. "Isn't that the stuff that blew up the Hindenburg? Is this Terminator W, Revenge of The Public Servants?"

Like a Hollywood porn queen cleansed by six weeks in a convent, hydrogen is back. This time safety measures are available to guard against catastrophe. In fact, prognosticators insist that what's likely to go boom is a global hydrogen economy. In his 2003 State of the Union Address, President Bush kicked off a hydrogen initiative with a price tag over $1-billion. The U.S. government's Department of Energy hopes H2 will handle ten percent of America's energy needs by 2030. A growing number of experts believe this colorless, odorless gas is the silver-bullet solution to our transportation, air-pollution, and energy-security concerns.

Governor Schwarzenegger seems serious about making hydrogen a star. Calling his specially modified Hummer "a vehicle of today capable of running on the furl of tomorrow," he's ready to start his SUV's big V-8 and motor on down California's Hydrogen Highway, an initiative aimed at proving the viability of this brave new fuel.

Hydrogen is hot, and not just in California, for two reasons. It's what we'll be pumping into our squeaky/green fuel-cell electric vehicles when they hit the street in 15 or so years. But a growing throng of engineers, scientists and backyard tinkerers are unwilling to wait; this group insists that the engine under the hood of your car can be broken of its gasoline habit and reprogrammed to run just fine on hydrogen. They also contend that lessons learned accumulating, storing, transporting and consuming hydrogen will advance us several miles down the governor's highway to the future.

BMW is hydrogen's biggest corporate booster. In 1978--when fuel cells were still the stuff of space travel--Bavarian engineers began modifying conventional engines to run on H2. The knowledge they learned will hit the road within five years in the form of production-line 7-series sedans capable of switching between gasoline and hydrogen fuels.

Hydrogen, which consists of one proton and one electron, is nature's most elegant and abundant element. It accounts for three-quarters of the mass and 90-percent of the atoms in the universe. Jupiter is literally full of it. On Earth, hydrogen is the ninth most abundant element, though its tendency to wander off into space makes it a stranger (one part in a million) in our atmosphere.

Combustion experiments began in the 16th century before hydrogen got its name. It burns nicely in air and makes a potent rocket fuel, but hydrogen also has a mean streak (H-bomb).

[H.sub.2] is the current darling of internal combustion engine fuels for the same reason it's so attractive for use in electric-car fuel cells: there's no carbon to foul up the energy-conversion process. Burn gas, an amalgamation of hydrogen and carbon, in an engine and most of the by-products spewing out the exhaust contain what's become the evil element (C): carbon monoxide (CO) is what kills you when you lock yourself in the garage with a car engine running. Partially burned hydrocarbons (HC) are a key constituent of smog. Carbon dioxide (C[O.sub.2]) is the greenhouse gas under attack for its presumed role in global warming.

Hydrogen, the most potent fuel going, packs nearly three times the energy of gasoline. It's easy to ignite and burns faster and hotter than high-octane gas. The exhaust consists mainly of steam (water in the vapor state). The only carbon by-products come from trace amounts of lubricating oil consumed during combustion.

Only minor changes are needed to switch engines from gasoline to hydrogen fuel The make-up of some internal components, such as valve seats, must be altered to guard against a phenomenon called hydrogen embrittlement--the tendency of hydrogen atoms to infuse the surface of welded or heat-treated steel, causing a lack of ductility and cracking. Also, local hot spots must be avoided to forestall premature ignition.

Were it not for its drawbacks, we'd already be pumping hydrogen into our tanks instead of gasoline. Beyond cost and availability, the major hydrogen headache is that it's a gas at room temperature. Its tiny little atoms slip right through clay, rubber and some metal containers. Condensing it into a liquid state requires cooling it to -423 degrees F, only 37 degrees above absolute zero. In spite of the bother associated with what's called cryogenic (super-cooled) hydrogen, BMW is convinced this is the way to go. Others, such as General Motors in the aforementioned Hummer application, prefer compressing the gas to 5,000 psi to increase concentration, with hopes of doubling that pressure in the near future. Three expensive carbon-fiber-reinforced tanks built into Schwarzenegger's Hummer carry 12 pounds of hydrogen, enough for a 60-mile cruise. In contrast, BMW's cryogenic method allows canting 24 pounds of liquid hydrogen inside a highly insulated, 80 psi, 45-gallon tank. That's enough fuel to power a large BMW sedan nearly 200 miles.