AIR QUALITY/Mobile source reduction helps city build plant
Like a number of local governments, San Diego County manages its air quality within a strict regulatory framework. That framework requires that any new sources of pollution be offset by reductions from other sources. In most cases, those offsets, or “credits,” come from emissions reductions at stationary sources, such as manufacturing facilities. Consequently, when San Diego County decided it needed a new power plant, a significant source of emissions, it had to search for a way to reduce emissions elsewhere.
The result of that search is a partnership involving the county, Houston-based Waste Management and the new Pacific Gas & Electric-owned Otay power plant. The ensuing project is the first in the nation to offset emissions from a new power plant by reducing pollution from mobile sources. The plan calls for replacing 120 diesel garbage trucks with new trucks fueled with 100 percent liquid natural gas (LNG), drastically reducing emissions of smog-forming nitrogen oxides and particulates.
The $33 million program, announced in September, is expected to reduce emissions of nitrogen oxides by more than 35 tons per year — the equivalent of removing 9,200 new passenger cars from San Diego County roads. The mobile air emission credits gained through the reductions will be used to offset emissions for the Otay Mesa Generating Project, a 500-megawatt plant to be built outside of San Diego and the first major power plant to be built in San Diego County in nearly 30 years. The plant will generate enough electricity to power at least 500,000 homes.
“We have a tremendous need for new generation in San Diego County, and this project will help meet that need,” says Greg Cox, the San Diego County supervisor in whose district the plant will be located. “Just as importantly, the innovative emissions offset program demonstrates that high environmental standards can be met at the same time new energy is generated.”
The utility will pay the difference in cost between replacing the existing trucks with updated diesel-fueled engines and replacing them with the more expensive liquid natural gas fuel systems. All 120 trucks are expected to be replaced within 18 months.
Officials from PG&E and Waste Management had to work closely with the San Diego County Air Pollution Control District to rewrite the regulations and create a methodology to use mobile emission credits to offset a stationary source. Additionally, the district had to work closely with local, state and federal environmental agencies, including the California Air Resources Board, the California Energy Commission and the USEPA, to get approval for new regulations.
The creation of a rigorous inspection and maintenance program that included immediate replacement of any part that would affect truck emissions was key to the project. “This program will change the image of the refuse trucks as well as limit the amount of pollution in the air, and it will bring new businesses into the San Diego region,” says Mayor Mark Lewis of El Cajon, one of the communities that will benefit from the project.
With all of the regulatory approvals in place, the project is moving forward. The Otay Mesa Generating Project was sold to another company in December, and ground was broken for an LNG fuel station in January. The first 30 LNG refuse trucks are in service.