Wednesday, October 24, 2007

Alternatives to Gasoline: Pros and Cons

The New York Times has a great special section today on cars. I didn't know that hybrid technology was an old idea.
http://www.nytimes.com/pages/automobiles/autospecial/

"Then in 1994, nearly a century after Porsche’s hybrid arrived on the scene, Akihiro Wada, executive vice president of Toyota, posed a challenge before a special team of company engineers: build a car with double the fuel efficiency of contemporary vehicles. Three years later, Toyota introduced the Prius in Japan as the world’s first mass-produced gas-electric car.

Today, the Prius competes with conventional sedans as a top seller in the United States, and nearly every major carmaker in the world has either introduced hybrids or is struggling to create the technologies to make cars more efficient."

I also found this article to be quite interesting

October 24, 2007
Challenging Gasoline: Diesel, Ethanol, Hydrogen

By MATTHEW L. WALD


YES, gasoline has the corner on the American car fuel market, but maybe not forever. Carmakers already produce passenger vehicles that run nicely on diesel fuel, ethanol or hydrogen. The first two are on the road in the millions around the world, and the third is moving slowly toward viability.

The catch is that the path to the pump, as Thomas Hobbes might have said, can be nasty, brutish and long. And the overall picture for pollution and energy — which the engineers call “well to wheels” — might have drawbacks to equal gasoline’s.

Still, the supply chains for diesel, ethanol and hydrogen are immature. That should change in a few years, as the most important choice for consumers in car showrooms may be what kind of fuel they want to use.

“Buying a car is not going to be about color choices or automatic versus manual transmission,” said Allen Schaeffer, the executive director for the Diesel Technology Forum, a trade association. “It’s going to be about getting into a powertrain.”

Here is a status report on the alternatives:

DIESEL

Carmakers are selling models in Europe that are clean, odor-free and peppy. Computer control over fuel injection has reduced diesel cars’ clattering noise, and ultralow-sulfur diesel, now widely available in the United States, has made it possible for carmakers to install filters and other devices to clean up the exhaust.

Chrysler and Mercedes-Benz are offering diesels in 45 states, and Mercedes is planning to sell one that meets the stricter requirements of California, which have also been adopted by New York, Massachusetts, Maine and Vermont.

Although diesel engines cost more to make and buy, they can make sense for a car owner. For one, they use fewer gallons per trip than gasoline engines.

Besides regular diesel fuel from petroleum, there is biodiesel. Chemicals extracted from soy or other vegetables, or from beef tallow or other animal fats, burn well in a diesel engine. These substances become waxy at low temperatures, so they are usually blended in small quantities with petroleum diesel.

But like ethanol, producing biodiesel requires farmland, which could otherwise be used to raise food. Yet making biodiesel takes less natural gas and other fossil fuels than making ethanol. A gallon of diesel will power a car 20 to 40 percent more miles than a gallon of gasoline, though the energy gain and the reduction in carbon dioxide emissions are not that large.

The reason is that diesel has more carbon than a gallon of gasoline. It also has more energy, about 138,000 B.T.U. versus about 118,000 for gasoline. That distinction may be lost on consumers, because motor fuel is sold by a unit of volume, the gallon, not a unit of energy.

Despite these issues, there is a real advantage to driving a diesel engine because it burns fuel at a higher temperature than a spark-ignited gasoline engine does, thus squeezing more work from the fuel.

Skeptics still abound. Lee Schipper, a former oil industry executive who leads a transportation and environmental study program at the World Resources Institute, said that what pushed European drivers to diesel was a tax policy that made the fuel cheaper, but buyers there tend to drive more, so they don’t save on total consumption.

“There are limits to diesel,” Dr. Schipper said. “Unless a diesel car is driven the same as a gasoline car, on 35 percent less fuel per kilometer, the CO2 benefit is marginal and may be negative.” Hybridization might be a better option, he suggested.

ETHANOL

The United States consumes about 140 billion gallons of liquid transportation fuel a year, about 6 billion from ethanol. Half of all gasoline contains some ethanol, which ordinary cars can burn at a concentration of up to 10 percent. About six million cars can now use any mixture of ethanol and gasoline, up to 85 percent ethanol, known as E85. Domestic carmakers view ethanol as a way to cut gasoline consumption and to avoid making major changes in their production.

Ethanol has strong political support. “I’d rather be paying farmers than the people overseas for the energy that fuels this country,” President Bush told auto workers at a speech at a Ford plant in Claycomo, Mo., this year. From a driver’s viewpoint, ethanol may perform well in the engine.

But it contains only about two-thirds as much energy per gallon as gasoline. It has what Dr. Schipper calls “closet carbon,” meaning carbon dioxide is created when ethanol is manufactured, which may amount to slightly less or more than in gasoline.

HYDROGEN

President Bush said in 2003 that there was hope that a baby born that year would grow up to buy a hydrogen fuel-cell vehicle as a first car. That baby is now nearly in kindergarten, and the fuel cell still has far to go.

Fuel-cell cars require improving two fairly young technologies, fuel cells and making hydrogen for them. Honda recently announced progress on the fuel cell, which combines hydrogen fuel with oxygen from air to make electric current, a little heat and some pure water.

Fuel cells are bulky, however. Honda’s first effort, in 1999, produced 60 kilowatts, enough for a modest-size sedan, but a fuel cell weighed close to 450 pounds and filled a volume of 4.7 cubic feet. This year it has given testers a new version that is 100 kilowatts; at about 150 pounds it is one-third the size of the old one. Honda’s trick was to turn the fuel cell sideways, to improve the flow of chemicals.

But Honda will not say what the fuel cell costs; no manufacturer is open about that.

On the hydrogen aspect, environmentalists dream of ranks of windmills making electricity that will be used to split water into hydrogen. They also wouldn’t mind fields of solar cells to do the same. But such renewable power may be more useful to replace coal, which is far dirtier than gasoline. And the cheaper way to make hydrogen may be the general technique, by taking it out of the methane in natural gas.

H2Gen, a small company in Alexandria, Va., is selling a chemical processing plant that can be delivered on a truck and turns natural gas into hydrogen fast enough to support fueling several dozen cars, about right for a corner gasoline station.

So far, H2Gen’s customers have been industrial users.

A Shell station in Washington that opened a hydrogen pump in late 2004, to supply the demonstration vehicles that automakers traipse through the city, uses hydrogen produced cryogenically. At either an oil refinery in Ontario or in Louisiana, the hydrogen is chilled to an extremely low temperature, condensing into a liquid. The result is pure, though it takes a lot of energy to make. It is then put into a cylinder truck with a diesel-powered engine and hauled to Washington, which works well for a test program but hardly saves any energy.

1 comment :

Anonymous said...

^^ nice blog!! ^@^

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