California Air Resources Board (ARB) Chairman Dr. Alan C. Lloyd yesterday directed staff to develop a program to reduce emissions from new on- road and off-road diesel engines by 75 percent beginning in 2007.

"Given what we've learned, with dedicated efforts from manufacturers, fuel suppliers, and ARB staff, we can expect near-zero emission diesel within a decade," said Dr. Lloyd .

The ARB, along with the U.S. Environmental Protection Agency (U.S. EPA),  and the California Air Pollution Control Officers Association (CAPCOA) are sponsoring a symposium, "Exploring New Technologies For Clean Air: Zero and Near-Zero Emission Technologies," from Tuesday through Thursday at the Beckman Center in Irvine.

The ARB is considering a two-pronged approach for cleaner diesel engines.  One is a reliance on emerging technology such as traps, filters, catalysts, and electronic engine monitoring to reduce particulate matter (PM) and nitrogen oxides (NOx) in diesel exhaust.  The key to making these technologies effective, however, is a reduction in the sulfur content of diesel fuel to 30 parts per million (PPM), from the current permitted levels of around 500 PPM.  The existing sulfur levels in diesel fuel poison advanced emission control technologies.

"We're delighted that Californians will be the first beneficiaries of the world's cleanest diesel technology," Dr. Lloyd said.  "The U.S. EPA must adopt a nationwide, low-sulfur diesel fuel standard for this strategy to be effective," Dr. Lloyd added.
 
The reduced sulfur diesel, combined with the new technologies for exhaust after-treatment, would cut NOx emissions to 0.5 grams (g) or less and PM to 0.01 gram.  Current diesel engine standards call for 4 g NOx and .10 g PM.  New standards that will begin in 2004 call for a reduction to 2 g NOx while PM remains at .10 g.

At Tuesday's forum session, the ARB also discussed new exhaust standards for urban transit buses.  Details of the new bus standards will be presented to the ARB Board at its January meeting. The proposal includes fleet averaging and incentives to accelerate the introduction of zero and near-zero emission technology.

As Chairman Lloyd observed, "Zero emission buses are already operating in California.  I've directed staff to take every reasonable step to expand their use at the earliest possible date."

One of Wednesday's sessions  focused on ways to reduce air emissions from a variety of so-called "off-road" equipment. The discussion looked at using fuel cells to power fork lifts, small generators and a variety of industrial and specialty equipment while an airline industry representative discussed the feasibility of converting airport ground support equipment from mainly diesel fuel to electricity or other cleaner sources of power.
 
The discussion also looked at small lawn and garden equipment engines that run on propane rather than gasoline, resulting in significant exhaust emissions reduction.  The off-road session concluded with a presentation on a diesel railroad locomotive that was converted to run on natural gas, thereby achieving a 75 percent reduction in NOx emissions.
 
Currently, diesel trucks make up about two percent of the on-road vehicle fleet but they contribute about 30 percent of the NOx and 65 percent of the PM from the on-road vehicle fleet.  NOx contributes to ozone, one of the most health- damaging components of smog, while PM has also been identified as a health hazard.