Published on April 22nd, 2014 | by James Ayre3
Hybrid Cars Significantly More Fuel-Efficient In India & China Than US
April 22nd, 2014 by James Ayre
Hybrid vehicles are significantly more fuel-efficient in India and China than they are in the US, according to new research from the US Department of Energy’s Lawrence Berkeley National Laboratory.
This disparity in efficiency between the different markets is down to exactly the same qualities that make driving in places like India so frustrating — heavy traffic, aggressive drivers, few freeways, etc. As a result, hybrids (or for that matter EVs) could be of even greater use to those living in crowded urban regions, such as India and China, than to those in more traditional markets.
The new findings are the result of a pair of studies that analyzed real-world driving conditions in great depth. Given the potential importance of the findings it’s not that surprising (and a good sign) that the government of India has already taken note.
“Currently greenhouse gas emissions from the transportation sector in India and China are a smaller piece of the pie compared with other sectors,” stated lead researcher Anand Gopal. “But vehicle ownership is going to skyrocket in these countries. That is why we decided to focus on this area. Hybrid and electric vehicles can significantly reduce carbon emissions and other pollutants.”
Especially since hybrids in India are considerably more fuel-efficient than they are officially rated. “With the official fuel economy test procedure currently used in India, fuel savings for hybrids are fairly grossly underestimated, showing only a 29% savings over conventional vehicles,” Gopal explained. “The test cycle is not representative of driving conditions in India, so that’s sending the wrong signal to the consumer.”
The press release from Berkeley Lab provides details about the work:
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 country — in 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 US fuel efficiency ratings, which include about 55% city driving and 45% highway driving.
They found that driving a hybrid would achieve fuel savings of about 47-48% over a conventional car in India and about 53-55% in China. In the United States, hybrids are rated to produce a fuel savings of about 40% 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.
With regard to the reasons for the findings, Saxena stated: “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 system — the electric motor, the batteries — enable the engine to operate at a higher efficiency operating condition. We weighed the importance of these three mechanisms against each other for the Indian vehicles, and found that the ability to increase engine efficiency was the most important reason, second was regenerative braking, then engine shutdown.”
The new findings are detailed in a paper published in the journal Applied Energy, and another paper soon to be published in the International Journal of Powertrains.
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