Each year, motor vehicles in the United States release about 350
million tons of carbon into the atmosphere in the form of carbon
monoxide and carbon dioxide. To reduce these emissions
significantly, a radically different propulsion system is
needed. Scientists and engineers working with the PNGV see the
hybrid vehicle as the most likely track for the car of the
future. Energy for the hybrid vehicle would be stored by
advanced batteries, flywheels, or ultracapacitors. Power source
candidates for the hybrid include small diesel engines, fuel
cells similar to those that power spacecraft, and gas turbines.
Technologies that would enable the hybrid to run efficiently and
reliably are largely dependent on how successful science and
industry are at developing new materials, including ceramic
materials. A hybrid electric vehicle with a gas turbine engine,
compared with spark ignition engines widely used today, would
weigh less, last longer, be more fuel-efficient, could burn a
variety of fuels, and would have lower