About 50 percent fuel savings over conventional cars
Gopal, working with Berkeley Lab scientists Samveg Saxena and Amol Phadke, used a powertrain simulation model called Autonomie to create a hypothetical hybridized version of the top-selling conventional car in each countryin China it was the Buick Excelle and in India the Maruti Alto. The reason for creating a hypothetical version was to isolate the improvement from hybridization and measure only that benefit.
For the India analysis the researchers simulated drive cycles in two Indian cities (New Delhi and Pune) taken from published studies and also used the Modified Indian Drive Cycle, the test for the official fuel economy rating. In China they simulated drive cycles in 11 cities and with three types of hybrid powertrains (start-stop, parallel and power-split). In both cases they compared it to drive cycles used for U.S. fuel efficiency ratings, which include about 55 percent city driving and 45 percent highway driving.
They found that driving a hybrid would achieve fuel savings of about 47 to 48 percent over a conventional car in India and about 53 to 55 percent in China. In the United States, hybrids are rated to produce a fuel savings of about 40 percent over their conventional counterparts. Currently hybrid and electric vehicles have a tiny share of the market in India and China and are seen as a higher-end product.
Gopal describes the traffic in India as "pretty slow, pretty crazy, always congested." In technical terms, the frequent starting and stopping, considerable amount of time spent idling, and low percentage of time spent on highways provide hybrids three ways to save additional fuel.
"One is regenerative braking, another is being able to turn off the engine when the car is stopped or in low-power condition, and another is that the hybrid systemthe electric motor, the batteriesenable the engine to operate at a higher efficiency operatin
|Contact: Julie Chao|
DOE/Lawrence Berkeley National Laboratory