Clearing some air

by Carolyn Chase


merican voters support tough new clean air controls for
big diesel trucks and other polluting vehicles according to a national public opinion survey released in June. That smelly black smoke emitted by big rigs should not be allowed, said an overwhelming majority of those questioned. Pollsters found that a breathtaking 90 percent of the people they queried want diesel vehicles to use the best available pollution control technology. Sixty-one percent support cleaner diesel fuel despite increased costs that could be passed on to consumers.

The survey was released as a coalition of state and local government and health and environmental groups called for the federal government to take tougher action to clean up big trucks, a major source of smog, soot and toxic air pollution. The U.S. Environmental Protection Agency is now reviewing standards for future trucks.

Quantitative risk assessment from exposure to diesel emissions was performed by the State of California in a process that led to the identification of diesel particulate emissions as a toxic air contaminant in August 1998. The Agency for Toxic Substances and Disease Registry, a U.S. government agency, reports that "Breathing diesel fuel vapors for long periods may cause kidney damage and lower your blood's ability to clot."

Frank O'Donnell, executive director of the Clean Air Trust, said today's truck standards "are so pitifully weak that most trucks do not use an available truck version of the catalytic converter used on automobiles."

Though tougher controls are being resisted by diesel engine makers, the petroleum industry and the trucking lobby, that same week, Navistar International Corp., makers of heavy and medium trucks and school buses, demonstrated its "green diesel" technology on a school bus in Chicago. Within the EPA's proposed applicable limits, particulate-matter emissions were reduced by more than 90% using their technology. This is another case where the technology exists if the leadership - both industrial and political - will require its use.

Here in San Diego, the City's Environmental Services Department is demostrating such leadership. They are in the initial phases of converting their fleet of diesel trash and recycling trucks to run on cleaner burning liquid natural gas (LNG). The city's trucks are the biggest remaining source of air pollution driving in every neighborhood on a weekly basis.

The City has entered into a five year agreement with Clean Air Partners of San Diego, a private company, to convert at least 54 of its heavy duty (55,000 lb) refuse packers to a dual fuel LNG/Diesel system. The system involves installation of LNG fuel tanks, lines, valves and regulators as well as a "duel fuel" injection system.

The Caterpillar Dual Fuel Compression Ignition Engine is 25-40% more efficient that all other options available. After the dual fuel conversion, a typical refuse packer in San Diego will consume only five gallons per day of diesel, with the remaining diesel being replaced by cleaner burning LNG.

LNG is the only hydrocarbon that does not react photochemically to contribute to the formation of ground-level ozone pollution. Each LNG truck will remove the equivalent of 100 cars worth of pollution off the road emitting 35 percent less of the cancer-causing nitrogen oxides.

In an outstanding leadership example of "closing the loop," Richard L. Hays, Director of the Environmental Services Department is also pushing to fuel the converted trucks with natural gas recovered from the Miramar landfill where the trucks deliver their loads. Natural gas is a byproduct of landfills and either escapes into the air or is burned off. Hays is investing in a process to recover escaping landfill gas, remove other pollutants and convert it into LNG for vehicle fuel. This cycle will significantly reduce the amount of pollutants such as carbon dioxide, carbon monoxide, and oxides of nitrogen and reduce the city's contribution to global warming. This project will also explore the potential for converting green waste collected by the City as well.

The truck conversions are being funded by a San Diego Air Pollution Control District grant in the amount of $1.77million and another $200,000 from the California Energy Commission. After the conversions, San Diego will have the largest municipal fleet using LNG in the country.

According to the grant requirements, the conversions must take place within two years and the vehicles must be operated on natural gas for at least five years. Environmental Services is hoping to convert its entire 124-vehicle fleet. This one area where the city is showing the leadership required to reduce pollution and not simply ignore it or encourage it.