New Energy Management Technology Gives Hybrid Cars Long Battery Life 1999-01-2468
New energy-and-power management technology makes low-pollution hybrid electric vehicles practical and competitive in performance with gasoline powered cars. The fuel-burning engine can now run at its most efficient speed and load, with the propulsion motor supplying acceleration power and the generator capturing deceleration power. Battery depth of discharge can be monitored and controlled to get long battery life. A heavy battery is not needed for long travel distance. For example, the new Toyota Prius hybrid car delivers 66 miles per gallon in city driving and has a range of 600 miles on a tankful of gasoline. When acceleration power is supplied from a battery, then the engine can be a high-efficiency type, such as the 43-percent efficient Meijer version of the Stirling-cycle engine. Hydrogen, a previously impractical engine fuel, can be burned in external-combustion Stirling engines. Hydrogen can now be compactly stored in carbon nano-tubes or lithium aluminum tetrahydride. A new electrolyzer can produce hydrogen with 93.2 percent efficiency. The energy in hydrogen made with 6-cents-per kWh electricity costs one-half the price of energy in gasoline.