Gold to go in diesel engines

Gold. It's not just for teeth anymore. Nanostellar is going to use it to save automakers money and make diesel cars run cleaner.

Michael Kanellos Staff Writer, CNET News.com
Michael Kanellos is editor at large at CNET News.com, where he covers hardware, research and development, start-ups and the tech industry overseas.
Michael Kanellos
3 min read
There's gold in them there catalytic converters.

Nanostellar, which specializes in molecules and materials for making diesel engines run more efficiently, has devised a new coating for the inside of catalytic converters--devices that reduce emissions before they leave a car's tailpipe--that will both cost less than traditional coatings and cut down further on pollution.

The secret ingredient is gold, explained CEO Pankaj Dhingra. The company combines gold along with platinum and palladium into a material called NS Gold that car and auto parts makers will sprinkle into a new line of cleaner catalytic converters. Ideally, NS Gold will increase oxidation activity, i.e. the chemical reaction that reduces pollutants, by about 40 percent compared with conventional catalytic converters and about 20 percent compared with the converters treated with materials Nanostellar already sells.

"At the nano level, gold becomes very active, but until now no one has been able to make it for automotive use," he said in an interview. "You have high temperatures, a huge amount of oxygen. At high temperatures most materials are not stable."

Although gold at the nano level can assume different colors, NS Gold lives up to its name. At Nanostellar's lab in Redwood City, Calif., CNET News.com saw a beaker of the material swirling in a liquid. The mixture looked like the inside of an Orange Julius machine.

Rising fuel prices combined with fears about global warming have sparked interest in diesel cars. Traditional diesels can actually be somewhat dirty, emitting unburned fuel as well as carbon and nitrogen gases. But several European car manufacturers have developed diesels that burn much cleaner than their historical counterparts. Add to that the fact that diesel cars often last longer and can go farther on a gallon of fuel than traditional gas cars, and the new diesels start looking somewhat green.

Already in Europe, these cars will come to the States over the next few years. Some cities have even rolled out diesel hybrid buses.

Diesel cars can also run on biodiesel, which leads to even lower greenhouse gas emissions. The materials produced by Nanostellar, which spun out of Stanford, can now be found in aftermarket converters, but next year a large auto manufacturer will release cars that include converters with its materials.

Other companies, meanwhile, have come up with additives for cleaner diesel fuel.

Precious metals inside catalytic converters exist to break down things like carbon monoxide. Gases from the combustion process enter the converter and, when they come into contact with the metals, recombine with other gases to make less harmful gases and byproducts.

Platinum, the traditional metal inside converters, is costly, running about $1,250 an ounce. The particles also clump together over time and lose their effectiveness.

Thieves in some parts of the country have taken to stealing the converters out of large trucks and cars. A big rig could have as much as $1,000 worth of platinum in it, although extracting it from the catalytic converter isn't easy.

Nanostellar already sells a catalyst material that consists of about two-thirds platinum and one-third palladium, a metal that sells for around $350 an ounce.

Substituting the platinum-palladium alloys for pure platinum can reduce the platinum budget in a Volkswagen Passat by $56 to $107, according to statistics from Nanostellar. Although the cost may not change the sticker price of a new car much, it adds up. Automakers spent about $2 billion on platinum in 2005.

NS Gold further reduces the platinum budget, cutting the price of the material an additional 20 percent, he said. Gold sells for around $680 an ounce.

Besides cutting the price, the three-way mixture should help insulate auto manufacturers a bit from the fluctuations of the commodities markets. If platinum drops and gold rises, the company can tweak the formula to curb the effects of any price changes.

The new material will also cut down on the unburned fuel that comes out of diesel engines, the source of the odor that follows diesels.

"All that smell part goes away," he said. "If you are behind an old diesel truck, that smell is all the unburned hydrocarbons."

The company says that interested manufacturers can now order samples.