With the California Resources Board’s dedication to achieving emission reductions from diesel sources, it came up with a plan that forced transit agencies to look at alternatives. One option that some have turned to is gasoline hybrids.

Alex Bernasconi, senior vice president of sales and marketing with ISE Corp., points out, “In Southern California, it qualifies as an alternative fuel,” which is what got ISE in the market. Kevin Stone, director of application engineering with ISE Corp., says, “Some of the properties were looking for an alternative to CNG as a fuel. Gasoline, on the heavy-duty side, is seen as an alternative fuel.”

He adds, “I think that there is some concern about the 2010 requirements and what that will do to the diesel space and the cost of operations and potential reliability impact. I think some are looking at that as a way to really hedge their bets on what the potential challenges might be in diesel. I think there is a lot more interest going into 2010 for the gasoline just because of that fairly significant change.”

Garth Ruttig with New Flyer Industries brings up the question as to whether this idea will really take off outside of California, where they are having to comply to stricter regulations. “We have heard from customers that more maintenance is required on the engine because it is gas-powered. Another factor is that the transit agencies already have diesel fuel on site.”

The Mechanics of Series
Stone explains, “If we look at most hybrids that are on the road today on the heavy-duty side specifically, it’s usually done with the diesel engine, rather than the gasoline. Some of that is because the torque requirements are higher and most of the transmissions built for the heavy-duty market base are for diesel engines.

“The gasoline engine specifically is higher speed and it won’t couple with a standard heavy-duty transmission just because the speed and power are not matched properly,” Stone says, “but with the series hybrid, there’s no link between engine speed, which gives that flexibility. It allows the engine to run at higher speed and be able to provide the power.”

Bernasconi clarifies, “From a hardware point of view, a series system does not have a transmission. It has wires that connect basically a generator to the driving motor that is on the axle as opposed to a parallel system that has a regular transmission and then it has a little boost system that’s got an electric motor that boosts the power that is going through the automatic transmission.”