Driving Hybrid Buses
Dozens of cities and school districts are getting good marks for
implementing hybrid buses that run on both diesel and electricity. In doing
so, they are helping to commercialize a technology that proponents say will
save fuel costs and prevent the release of harmful emissions.
Utilities are making a contribution to the cause. Duke Energy, Progress
Energy, Dominion North Carolina Power and North Carolina electric
cooperatives are participating with school districts nationally -- all part
of a broader business and government consortium interested in seeing
electric vehicles take off. The endeavor is well-timed given the attention
paid to oil security and climate change along with the technical
improvements in battery technology. While commercialization is the ultimate
goal, market support is still largely absent.
"There's an adoption cost and it is fairly high," says Ewin Pritchard,
hybrid program manager for Raleigh-based Advanced Energy that facilitates
programs such as one recently adopted by the Austin, Texas, school district.
"There are incremental costs. But as more units are bought, the price per
school bus drops down to a stable number."
At present, hybrid buses cost about $225,000 each, or about three times that
of a conventional diesel bus. Once 1,000 buses come to market, Pritchard
says that the premium over-and-above a traditional bus will be $40,000. If
the typical bus last 15 years, the hybrid school bus will pay for itself
after the eighth year of ownership. That equates to $6,500 a year in fuel
savings in combination with reduced maintenance. Altogether, hybrids buses
are said to increase energy efficiency by 40 percent.
Hybrids are best suited in city traffic. When those vehicles apply their
brakes, electrical energy is generated that is stored from the battery. As a
result, there's reduced fuel use and lower emissions. The hybrid vehicle
industry says that if a fraction of the nation's 500,000 school buses can be
replaced, it would displace billions of gallons in gasoline.
The evolution can only be good for consumers and the environment. While
today's hybrids are recharged by an electric motor that converts power from
the gas engine to electric power, tomorrow's hybrids may be of the plug-in
variety that can be charged through the electrical outlet at night. If the
idea comes to fruition, then consumers will experience not just convenience
but also cleaner air and cheaper transportation costs.
"The hybrid electric school bus project is an exciting example of how key
stakeholders from the utility industry, business and government can form
partnerships that produce great benefits for communities in which we live,"
says Ellen Ruff, president Duke Energy in the Carolinas, which is interested
in plug-in hybrids.
Overall Evolution
As part of its wide range of fuel-efficient advanced technologies, General
Motors has also developed a commercial parallel hybrid system that combines
a diesel engine with electric motors to power transit buses.
It's already delivered more than 200 hybrid buses to the city of Seattle.
They are said to save 750,000 gallons of fuel per year over the buses they
will replace. Over the 12-year life cycle of the vehicles, the total savings
is expected to be 8 million gallons of fuel. If America's nine largest
cities replaced their transit fleets -- totaling 13,000 buses -- with hybrid
buses, GM says that the cities would save 40 million gallons of fuel each
year.
"You get low emissions, great fuel economy, smooth and quiet operation, but
one other thing is acceleration," says Tom Stephens, group vice president of
GM Powertrain.
To be sure, not everyone is a fan of hybrid buses. They are cost prohibitive
and critics say that the estimated fuel mileage and subsequent fuel savings
may not materialize. A typical bus may get six miles to the gallon while a
hybrid may get 12 miles to the gallon -- making return on investments
currently out of reach.
In the case of Seattle, fuel efficiencies have not worked as advertised
because some of the buses are used on suburban routes where they don't
benefit from stop-and-go traffic. Others say that federal emissions
standards are getting stronger and turning less expensive diesel buses into
cleaner-running machines.
But, no one disagrees that the hybrid buses require less maintenance and
that they are quieter. Those buses have the capacity to run hundreds miles
between fill-ups, says Advanced Energy's Pritchard. That's because battery
technology is always improving. As such, the kilowatt-hour per square foot
is better than ever. As the hybrid bus industry gains experience, its
products will become less expensive and more reliable.
That's how Madison, Wis., sees it. It is investing in five new
GM-manufactured buses as part of a city-wide initiative to improve
sustainability and air quality. According to the National Energy Renewable
Laboratory, those buses will cut emissions from nitrogen oxides by 39
percent, particulate matter by 97 percent, carbon monoxide by 60 percent and
hydrocarbons by 75 percent.
"These buses are good not just for the environment, but for the city's
bottom line," says Madison Mayor Dave Cieslewicz. "With the cost of diesel
fuel continuing to rise, Metro's hybrid-electric buses will save taxpayer
dollars as well as conserve fuel."
Hybrid buses are part of a phenomenon that is demanding the manufacture of
cleaner vehicles. It's the free market at work. The problem is that those
buses are now expensive and untested over time. With more production,
however, the costs are expected to decline while the overall quality will
improve. To get to that point, public-private partnerships must form and
ones that will likely involve the utility sector.
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