Other tech: heavy duty trucks and buses use half of fuel in the US a good target for efficiency

Tweet Hybrid buses consume about 20 percent less fuel.Fuel consumption in electrical utility trucks can be reduced by 50 percent with hybrid technology, in large part because, rather than idling the engine at a worksite to power the hydraulic lift used by linemen, the system can be run by batteries, which is much more efficient than idling a large engine. Eaton, based in Cleveland, OH, has already built and tested such a truck, and expects to have 24 of them in operation this year.

An even more immediate impact could come from retrofitting vehicles such as garbage trucks and delivery trucks with hydraulic hybrid systems. While conventional hybrids capture energy from braking and store it in a battery or ultracapacitor, these systems store energy produced by braking by using hydraulic fluid to compress nitrogen gas. The energy in the compressed gas can then be released to power acceleration. Van Amburg says these can be relatively easy and inexpensive to install -- an important consideration for a system to be fitted into an already depreciated vehicle.