The California Air Resource Board’s (CARB) recent decision to preserve the two-path, fuel-neutral policy gives local transit agencies the flexibility to invest in the best transportation option for their community. As part of the October 20, 2005 decision, CARB will require that for every new diesel bus purchased, transit agencies will need to either retrofit an older diesel bus or diesel-powered service vehicle with a NOx reducing after-treatment device, to reduce emissions.
Following adoption of the 2000 CARB fleet rules, most Bay Area transit operators committed to the diesel fuel path and by doing so made substantial investments in clean-air technology.
Bay Area efforts are paying off. Bay Area diesel bus emissions have dropped significantly in the past five years (see charts below). Annual emission savings gained by installing 1,696 Cleaire-Longview devices on Bay Area buses have allowed Bay Area operators to surpass CARB requirements by impressive margins:
- 410 tons of oxides of nitrogen (NOx)
- 16 tons of particulate matter (PM)
- 93 tons of hydrocarbons (HC)
- 335 tons of carbon monoxide (CO)
Dollar for Dollar – Clean Diesel Beats Compressed Natural Gas (CNG)
Had CARB eliminated the diesel path, CNG conversion would have cost the MTC region upwards of $270 million over and above what Bay Area operators would expend on maintaining its existing clean diesel fleet. The cost of forcing transit agencies to divert to alternative fuel systems would have resulted in service cuts – forcing some riders back into their cars and depriving transit-dependent populations access to vital destinations. Moreover, the limited, short-term emission reductions gained by a CNG mandate would have been eliminated by the construction emissions to build a new alternative fuel infrastructure.
For a relatively small cost per ton, the Bay Area has achieved significant reductions in NOx and PM emissions using clean diesel after-treatment technologies.
Local Investment and Clean Air Gains
With 13 of 16 Bay Area bus transit agencies committed to the diesel path, our region has invested over $300 million cleaning up diesel buses and researching fuel cells, including $100 million for clean diesel technologies that realize emissions savings beyond CARB requirements.
- $144 million on diesel-electric hybrid buses
- $88 million on repowering vehicles with cleaner diesel engines
- $34 million on Cleaire/Longview after-treatment
- $33 million on zero emission technologies
- $1 million on fuel demonstrations and component testing
Fuel Cells – One Step Closer To Reality
Bay Area transit operators are also making gains demonstrating fuel cell technology. The Santa Clara Valley Transportation Authority (VTA), in partnership with the San Mateo Transit District (SamTrans), is now running three zero emission buses in revenue service on some of their busiest transit routes, and the East Bay’s Alameda Contra Costa Transit District (AC Transit), in partnership with Golden Gate Transit, is set to put a fuel cell-battery hybrid bus in revenue service in December.
CARB Flexibility Improves Bay Area Air Quality: Hybrids to Hit The Street
San Francisco Muni and the Livermore-Amador Valley Transit Authority recently purchased diesel-electric hybrid buses similar to the ones running in Yosemite National Park. Samtrans and Fairfield-Suisun Transit are also poised to procure hybrid buses in the next few years.
The diesel-electric hybrids use 25-35% less fuel, reduce particulate matter by 90% and reduce nitrogen oxides by 40%.