The Down and Dirty on Hybrid Buses

From the Union of Concerned Scientists’ HybridBlog, a report on diesel hybrid transit buses and how they compare to their traditional counterparts. The bottom line: “a promising, but cloudy future”:

As with other hybrid technology used in cars and trucks, there is a perception that hybrid buses not only save fuel, but inherently are cleaner than their non-hybrid counter parts. As we have previously noted on HybridBlog, hybrids can have lower emissions, but they don’t automatically come that way. The same goes for hybrid transit buses. A recent study by the University of Connecticut measured the particulate emissions from two hybrid transit buses and two conventional diesel buses in over-the-road tests. The researchers found no decrease in particulate emissions from the hybrid buses compared with the conventional diesel buses.

The same goes for fuel efficiency: often, observers see gains for hybrids, particularly hybrid fleets of buses, but many factors, including “series or parallel hybrid design, system optimizations, and the type of bus route” affect the findings. Writer Don Anair notes that the potential for significant reductions in emissions and improvement in fuel efficiency exist, but we simply don’t have enough real-world data at this point to say we’re actually reaping those benefits.

I worry about “hybrid” becoming more of a feel-good concept than a practical step towards sustainability. Clearly, the technology can do a lot of good, but I have to wonder if automakers will really move towards optimizing this technology if they believe they can sell hybrid vehicles simply on green perceptions alone…

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