Abstract:Hybrid-electric vehicle teclmology has been reviewed and developments that have occurred in the period 1990-2000 highlighted with particular attention being given to their resultant effect on light-duty vehicle emissions and fuel economy. Electrical energy storage technologies (pulse batteries and ultracapacitors) are considered in depth and control strategies for series, parallel, and dual mode hybrid drivelines are described with emphasis on how the different strategies influence vehicle emissions and energy consumption. Hybrid vehicle operation for drivelines using various engines (fuel injected gasoline, diesel, and Stirling) and fuel cells (fueled with compressed hydrogen) is simulated for the Federal Urban and Highway driving cycles. The simulation results are utilized to compare the emissions and energy consumption of many hybrid vehicle designs with those of battery-powered electric and conventional ICE vehicles of equivalent size and performance. The emission comparisons are made based on full fuel cycle emissions starting at the powerplant, refinery, and hydrogen generation station for each of the vehicle types. Energy efficiency is described in terms of gasoline equivalent fuel economy and full fuel cycle CO2 emissions. The marketing and regulation of hybrid-electric vehicles are reviewed in light of the California ZEV Mandate and the initial experiences of auto companies in leasing and selling battery-powered and hybrid vehicles.

The technology review indicated that in the last ten years much progress has been made in the development of components for both battery-powered electric and hybrid-electric vehicles. The auto industry now has available technology for the design of ultra-clean vehicles utilizing several driveline options, including battery-powered and fuel cell electric and engine-powered hybrids with an electric range from zero to that close to a battery-powered EV. The mass-produced cost and customer acceptance of these various technology options is unclear at the present time and which of the options will be pursued in the near-term by the auto industry depends on their assessment of these factors.