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THE NATIONAL
CLEAN BUS NETWORK
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TECHNOLOGIES
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Vehicle engineers have been
focusing on two strategies to reduce emissions from the tailpipe.
One strategy reduces emissions per vehicle mile traveled by
improving fuel economy. This focuses on engine design and
efficient propulsion systems. Another strategy is to treat the
emissions as they exit the engine. This focuses on technologies
like emissions filters.
Hybrid-electric
propulsion
By placing electrical
generators in the wheels and a battery pack on board, heavy-duty
vehicles can improve their fuel efficiency by up to 50 percent.
Hybrid vehicles provide many other benefits. They can be
integrated with any fuel type and any after-treatment technology,
keeping open to fleet operators a variety of fuel and technology
combinations to reduce emissions. They can also reduce the need
for engine idling when the vehicle comes to a stop. The hybrid
vehicle market is in the pre-commercialization stage and will grow
significantly in the next five years.
After-treatment devices
Scientists are
developing emission control devices for heavy-duty vehicles. These
efforts are designed to meet EPA requirements that new heavy-duty
engines beginning with model year 2007 meet stricter engine
certification standards. Scientists are focusing particularly on
the development of after-treatment devices (like filters or
catalytic converters) that can reduce the levels of nitrogen
oxides and particulate matter at the tailpipe.
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