Lev III Paints Bleak Future For Diesel
Tom Murphy Ward's AutoWorld, Nov 1, 2009 12:00 PM

The California Air Resources Board has a lot to do with German auto makers' sudden interest in hybrids and electric vehicles. German diesels might soon become endangered species if newly proposed emissions standards take effect.

Representatives from auto makers, the U.S. Environmental Protection Agency and non-governmental organizations have met recently with CARB to discuss LEV III, the next step in California's Low Emission Vehicle program.

CARB has demonstrated over the years its desire to enact and enforce the world's strictest tailpipe-emissions regulations. It adopted LEV in 1990, and the first regulations were in place through 2003. The more stringent LEV II requirements took effect in 2004 and will be in place until 2014, when LEV III is slated to begin.

Meetings with CARB to work out the details of LEV III will continue through the end of this year, and auto makers expect the standard to usher in emissions codes that will favor EVs and force rapid adoption of new technologies to dramatically boost fuel efficiency for internal-combustion engines.

Diesels, which emit higher levels of oxides of nitrogen and hydrocarbons, face a severe challenge if they are to meet the LEV III mandate in its current form.

LEV II currently limits combined NOx and HC emissions to 140 mg/mile, based on the stringent US06 supplemental federal test procedure. LEV III would push this threshold to 30 mg/mile, based on the same US06 cycle, a reduction of 70%.

Even advanced clean diesels available from German auto makers today could no longer be sold in California without significant new technology developments, says Guenter Schiele, manager-diesel engineering for Volkswagen Group of America.

The test cycle is problematic because US06 requires driving at a maximum speed of 80 mph (129 km/h) and an average speed of 48.4 mph (78 km/h). The more moderate cycle is the standard FTP (federal test procedure), which requires a maximum speed of 57 mph (92 km/h) and average speed of 21 mph (34 km/h).

Schiele says powertrain engineers consider the FTP cycle more representative of typical U.S. driving habits than US06, and that the industry is suggesting CARB consider a “weighted” standard that combines results from various test cycles.

“Right now, from 140 milligrams per mile, I would say 100 or 80 milligrams per mile could be reached with the US06 test cycle,” Schiele says. “But to reach 30 is a tough thing. I say the technology won't be available.”

Still, he does not cast aside CARB's proposal as impossible because the agency allows a phase-in period of eight to 10 years.

History favors CARB's position. Ten years ago, diesel engines were a lot cleaner than they were in the 1980s, but they still could emit NOx at a rate of 600 mg/mile. Today, the NOx limit, alone, is 50 mg/mile for passenger cars.

Auto makers met the new standard for diesels with German-led development of NOx storage catalysts and selective catalytic reduction.

“If someone told us 10 years ago we must lower emissions to 50 mg, then everyone would have said that's not possible, there's no technology available,” Schiele says. “And we did it.”

It's too early to predict whether new technology will allow diesels to meet the new mandate, but Schiele says near-term work must focus on pre-heated catalysts and better insulation of the engine and exhaust system to limit cold-start emissions.

CARB is expected to finalize its LEV III regulations in spring 2010.