A pioneering program by one of the world's largest cities to switch its vehicle fleet to clean fuel has not significantly improved harmful vehicle emissions in more than 5,000 vehicles and worsened some vehicles' climate impacts a new University of British Columbia study finds.
The study which explores the impacts of New Delhi, India's 2003 conversion of 90,000 buses, taxis and auto-rickshaws to compressed natural gas (CNG), a well-known "clean" fuel provides crucial information for other cities considering similar projects.
Of the city's more than 5,000 auto-rickshaws with two-stroke engines a common form of transportation in Asia and Africa the study found that CNG produced only minor reductions in emissions that cause air pollution and an increase in emissions that negatively impact climate change.
According to the researchers, the New Delhi's program could have achieved greater emission reductions at a cheaper price by simply upgrading two-stroke models to the cleaner, more fuel-efficient four-stroke variety.
"Our study demonstrates the importance of engine type when adopting clean fuels," says lead author and UBC post-doctoral fellow Conor Reynolds. "Despite switching to CNG, two-stroke engine auto-rickshaws in Delhi still produce similar levels of particulate matter per kilogram of fuel to a diesel bus and their climate impacts are worse than before."
Published online in the journal Environmental Science and Technology, the study is the first to comprehensively examine the pollutant emissions from small vehicle engines fuelled with CNG. It included significant laboratory testing of Indian auto-rickshaws.
The study finds that as much as one third of CNG is not properly burned in two-stroke engines, producing high emissions of methane, a major greenhouse gas that contributes to climate change. CNG use also produced substantial emissions of high particulate matter from unburned lubricating
|Contact: Basil Waugh|
University of British Columbia