Board may let the diesel hybrid buses roll.

The California Air Resources Board, historically an opponent of pollution-causing diesel use, will consider relaxing its standards to allow transit agencies to purchase diesel hybrid fleets.

Under an amendment proposed by the board's staff, CARB would allow the use of diesel-electric transit buses as another choice among vehicles run on compressed natural gas and other alternative fuels. A hearing on the proposal is planned for June 24 in Sacramento.

CARB staff members have been fielding complaints about compressed fuels from automakers and fleet operators.

"We're trying to provide an (alternative) for bus companies that feel the need for diesel buses because of the hills and the climate that make it tough for compressed natural gas," said Jerry Martin, a CARB spokesman. "Those hybrid buses would be much cleaner than the buses that are on the streets right now. It is a move in the right direction."

Advocates of the amendment, including the Engine Manufacturers Association, maintain that hybrids have tested as well as CNG-powered vehicles for low emissions, and they are more reliable on hilly terrain and cold weather.

The measure is part of a series of proposed changes that include synchronizing the state's 2007 diesel standards with the less stringent 2007 rules established by the federal Environmental Protection Agency.

Hybrid buses run on mostly electrical power until the vehicles reach speeds of 40 to 45 miles per hour, or meet resistance in the form of a steep incline or harsh weather conditions. That's when a computerized control system switches over to full use of diesel fuel.

Lower emissions

When diesel fuel is burning in conjunction with electrical power, emissions are 50 percent lower than a fully diesel-powered vehicle, advocates say.

But the level of pollutants would not be low enough for many environmental groups to back the program. The groups claim the rollbacks would send a message to vehicle manufacturers that they can skirt CARB standards.

The Natural Resources Defense Council, for instance, wants CARB to press forward with programs that emphasize use of alternative fuels.

"We're not trying to favor a technology," said Diane Bailey, an NRDC scientist. She said the organization was just concerned with "what's coming out of the tailpipe."

The NRDC is also not pleased with a proposal to relax state nitrogen oxide emission standards to less-stringent federal levels going into effect in 2007.

Under the current California mandate, diesel emission limits from vehicles are scheduled to drop to a maximum of 0.2 grams of nitrogen oxide per brake horsepower-hour (the base standard used in the industry) by 2007, from the current limit of 0.5 grams.

Under EPA rules, diesel engine manufacturers have to start phasing in the goal of 0.2 grams beginning in 2007, with full compliance by 2010.

The small number of hybrids that could potentially go into fleet service by that time would likely meet the existing California mandate, but other diesel-powered vehicles--in far greater use--may not.

"It means relaxing California standards because (CARB) is worried that there will not be any buses that will be available in 2007 to meet the current California 2007 standards," said Bailey. "However, several engine manufacturers have made public commitments that they will be able to meet those standards in time."

California's diesel standards--the most stringent in the nation--were approved a few years ago, just before the EPA passed its regulations.

Fans in Washington

Diesel hybrid vehicles have drawn support in Detroit and Washington D.C. They are seen in some quarters as a temporary bridge before the mass introduction of hydrogen-powered fuel-cell vehicles, which are still as far as a decade away. Currently, a hydrogen-powered car would cost about $1 million; a bus would cost $3 million.

Hybrid fleet engines are made by General Motors Corp., DaimlerChrysler AG and a few smaller engine makers.

At an 8-year-old Torrance-based operation, GM engineers developed the advanced propulsion system for the hybrid engines made by the company's Allied Transmission Division in Indianapolis.

GM and its partners have sold 40 test diesel-hybrid vehicles to cities nationwide, including two to the city of Norwalk. The company is building 235 hybrid buses for King County, Wash.

"Our hybrid system, when you couple it with a diesel engine provides significant emission reductions," said Bob Babik, GM's director of vehicle emissions. "I don't see why (CARB) wouldn't pass it. I don't see where there are any downsides."

GM shut down its EV-I electric car operation two years ago after investing $1.5 billion in research and development. The program, spurred by the California zero-emission rules that have since been relaxed, leased a mere 800 vehicles over a four-year period. Consumers balked at the price of electric cars and the inconvenience. They had a range of only about 100 miles and required lengthy recharging times.

CARB originally launched its zero-emissions program in 1990 after seeing GM's first battery powered car. The industry spent the next decade battling state regulations in court.

"We can't afford to lose that much money on any particular program," said Dave Barthmuss, a GM spokesman.