When idling at a stop sign or moving at slow speeds, it relies on its quieter, more efficient electric engine. When the driver needs a little pickup on the highway, the gas engine kicks in. Swedish automaker Volvo unveiled the first large commercial hybrid truck last month. It can cover 19 miles, without exhaust or noise, on its electric engine. But there's still much work to do.
Hybrid cars are heavy, thanks in part to their large nickel-hydride battery packs.
And perhaps more disturbingly, they fare poorly in crash tests. But biomass is a huge resource. It is being used to produce cleaner fuels such as ethanol and methanol. Municipal solid waste, of which 60 percent to 70 percent is biomass, is already being drilled into to collect methane. Biomass can also be used in place of fossil fuels for coal firing.