The Power and Transportation Future - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 257

tion in the last few decades. This has resulted in a significant reduction in
the number of underground fuel storage tanks.
THE ELECTRIC AND HYBRID FUTURE
The internal combustion engine, running on gasoline, has been pow-
ering transportation for almost a century. Advances in engines and fuels,
such as reformulated gasoline, have reduced the pollution of these en-
gines. Competitors such as electric cars and natural gas vehicles have not
been able to penetrate their dominance. The competition for fuel cell vehi-
cles includes hybrid vehicles and diesels, which are seeing many advances
today.
Hybrid gasoline electric-powered cars can be twice as efficient as in-
ternal combustion vehicles. An onboard energy storage device, which is
usually a battery and sometimes a special capacitor (called a super capaci-
tor), increases the efficiency greatly. Regenerative braking is also used to
capture energy that is normally lost when the car is braking. The engine
is turned off when the car is idling or decelerating. Gasoline engines have
lower efficiencies at lower rpm so the gas engine operates only at higher
rpms and is more efficient more of the time. In city driving, non polluting
electric power is used.
The first-generation Toyota Prius had a city mileage of 52 miles per
gallon (mpg) and a highway mileage of 45-mpg. The second-generation
Prius, appeared in 2003 with improved mileage numbers. Toyota has been
introducing other hybrid models along with most auto manufacturers that
plan to produce hybrid vehicles.
DIESEL POWER
Another competitor for fuel cell vehicles could be the diesel engine.
Diesel engines are used in large trucks and construction equipment for
their high efficiency and durability.
Modern diesel engines are much different from the engines of the
1970s and 1980s. Advances have included electronic controls, high-pressure
fuel injection, variable injection timing, improved combustion chamber de-
sign, and turbo-charging. They are 30 to 40% more fuel efficient than gaso-
line vehicles. The production and delivery of diesel fuel releases 30% less