Honda Patents Plasma Technology to Clean Diesel Fumes (Update3)
May 26 (Bloomberg) -- Honda Motor Co., aiming to build the first diesel car that meets pollution rules across the U.S., patented a new method to curb smog-forming gases.

The tailpipe emission of nitrous oxides has clouded diesel's appeal in the U.S., the world's biggest auto market. Honda is betting that the new technology will win customers attracted by the greater fuel economy and faster acceleration of diesel cars.

In Honda's treatment system, exhaust flows through a plasma reactor, or gaseous layer of electrically charged atoms, according to a U.S. patent obtained by Bloomberg News. That separates out harmful nitrogen oxides and forms nitrogen dioxide that's then reduced or absorbed by alkali metals and silver.

``If they can get it out there, it's an engineering tour- de-force,'' said Robert Weber, who analyzes exhaust systems for Tiax LLC, a Cambridge, Massachusetts-based consulting firm.

No automaker has built a diesel-powered car that can meet pollution rules in California and some Northeast states, which are tougher than federal requirements. DaimlerChrysler AG and Volkswagen AG, the largest sellers of diesel autos, are working on systems that would meet the stricter rules by squirting urea, an ammonia-based chemical found in urine, on diesel fumes.

Diesel emissions, including nitrogen oxides and other harmful gases, have been linked to cancer, asthma and lung and heart disease.

Honda, the world's largest engine maker, aims to sell a U.S. diesel model by 2009, five years after introducing its first such car in Europe. The company hasn't said which models will be available with its new engine. Takeo Fukui, Honda's president, said May 23 that diesels may eventually be available in the U.S. in the Odyssey minivan and Acura MDX sport-utility vehicle.

30% More Efficient

Diesel vehicles can travel as much as 30 percent farther on a gallon of fuel than gasoline-powered cars, Ed Cohen, Honda's Washington-based government affairs official, said last week.

Diesels are also appealing because they generally have more torque, allowing vehicles to surge forward from a standing stop. Six-cylinder diesels can provide as much torque as V-8 gasoline engines, said Simon Godwin, DaimlerChrysler's regulatory affairs manager in Washington.

David Iida, a spokesman for Honda's U.S. unit, declined to comment on the contents of the 19-page patent, issued on May 16, the day before the company announced plans for a U.S. diesel.

Diesel Sales

Diesel vehicles were 3.2 percent of new light vehicle sales in the U.S. in 2005, according to J.D. Power & Associates.

Interest in alternatives to traditional gasoline-engine autos is growing in the U.S. amid near-record fuel prices and concern about emissions of carbon dioxide and other gases linked to global warming.

Diesel vehicles typically emit less carbon dioxide than equivalent gasoline autos, broadening their appeal in western Europe, where about half of new cars are diesels. Diesel fuel also is taxed at a lower rate in Europe, making it cheaper.

Diesel is more expensive in the U.S. than regular grade gasoline, according to AAA's Daily Fuel Gauge report Web site. Gasoline cost an average of $2.863 a gallon, 35 percent more than year ago, according to AAA. Diesel costs $2.949, 31 percent more.

Honda has said it expects to meet U.S. ``Tier-2, Bin-5'' level emissions with its diesel. That's roughly equivalent to the lowest level acceptable in California, according to the state's Air Resources Board.

California Rules

California since the early 1970s has had federal authority to set air-pollution rules that exceed national standards. U.S. states have the option of adopting either U.S. or stricter California rules.

Among diesels sold in the U.S., Volkswagen's diesel Golf small car and Chrysler's Jeep Liberty are rated Tier-2, Bin-10 by the U.S. Environmental Protection Agency, making them too dirty to be sold in states including California and New York.

Honda's diesel system uses electricity to generate and maintain the plasma, drawing energy from the engine. It may require as much as a kilowatt of power, or about the same amount needed to power headlights, Tiax's Weber said.

``You're basically running a small generator,'' he said. ``That's been one of the major hurdles of plasma systems, because it starts to affect fuel economy.''

For the engine to be a success, Honda has to solve that problem, reduce the cost of manufacturing a plasma treatment and achieve the required low-emission results, Weber said.

Companies including Delphi Corp., Ford Motor Co., Eaton Corp. and Caterpillar Inc. have also studied using plasma systems to reduce emissions, Weber said.

``If Honda makes this work, they've done very good system- level tweaking and tuning of every aspect of the vehicle,'' Weber said.

Honda's U.S. operations are based in Torrance, California. The company's American depositary receipts rose 25 cents to $33.56 at 4 p.m. in New York Stock Exchange composite trading. They have gained 16 percent this year.

(To view Honda's U.S. patent for its diesel exhaust system, see http://patft1.uspto.gov/netahtml/PTO/srchnum.htm and type in patent number 7,043,902.)