Exploring Alternatives

Hybrid Drives

By recapturing energy from braking for use in acceleration and propelling vehicles up hills, hybrid technology can reduce fuel consumption, as well as air and noise pollution.

Thanks in part to a grant from the Bay Area Air Quality Management District, AC Transit is evaluating a prototype gasoline-electric hybrid 30′ neighborhood bus.

AC Transit’s Climate Action Plan also calls for the gradual replacement of its older conventional diesel buses with diesel-electric hybrids, which could reduce AC Transit’s fuel consumption by about 30%. While current economic constraints preclude the immediate purchase of diesel-electric hybrids, these vehicles remain part of AC Transit’s Short Term Transit Plan.

Biodiesel

Biodiesel is an alternative to traditional diesel that can be produced from a variety of plant materials. In addition to potentially reducing overall carbon emissions, biodiesel offers the opportunity to reduce dependence on foreign oil.

In 2007 and 2008, AC Transit participated in a comprehensive, real-world study comparing six buses operating on B20, a blend of 20% biodiesel and 80% petroleum diesel, with six vehicles using 100% conventional diesel. The fuels were tested for 18,000 vehicle miles in several bus models, as well as in a laboratory environment using a heavy-duty chassis dynamometer. The study found no statistically significant difference in NOx emissions, engine performance, or engine wear-and-tear between B20 and CARB-approved ultra-low sulfur diesel. However, the use of B20 resulted in slightly lower fuel economy compared to CARB diesel fuel.

Between the additional cost for biodiesel, the lack of reliable local suppliers, and the reduced efficiency, AC Transit is not currently using biodiesel. However, as the biofuels industry continues to advance, we are continually reevaluating biodiesel’s potential use.