Fuel-efficient tech has a dark side

New automotive technology that promises enhanced fuel efficiency may have a serious downside, including significant climate and public health impacts, according to a new study.

New research from the University of Georgia College of Engineering is shedding some much-needed light on the potential dark side of the gasoline direct injection (GDI) engine, which many car manufacturers have adopted in an effort to meet the fuel economy and carbon emission goals of the U.S. Environmental Protection Agency.

The researchers have discovered that GDI engines in fact produce more black carbon aerosols than traditional port fuel injection engines. Black carbon absorbs solar radiation and contributes to climate warming.

According to their study, the increase in black carbon emissions from GDI-powered vehicles is predicted to fuel climate warming in urban areas of the U.S. that significantly exceeds the cooling associated with a reduction in CO2. What’s more, the shift to GDI engines is expected to nearly double the premature mortality rate associated with vehicle emissions, from 855 deaths annually to 1,599. The researchers estimate the annual social cost of these premature deaths at $5.95 billion.

While previous research has reported the shift to GDI engines will result in net benefits for the global climate, the UGA researchers say these benefits are rather small and can only be realized on timescales of decades. Meanwhile, the negative impact of black carbon can be felt instantaneously.

“Even though emissions from gasoline vehicles constitute a small fraction of the black carbon in the atmosphere, the vehicle emissions are concentrated in regions with high population densities, which magnifies their effect,” said the study’s principal investigator Rawad Saleh.

What’s more, this new study calls into question previous studies concluding that the shift to GDI engines will result in net benefits for the global climate.

“Our research shows the climate trade-off is much different on the regional scale, especially in areas with high vehicle densities. In these regions, the climate burden induced by the increase in black carbon dominates over the climate benefits of the reduction in CO2,” explained Saleh.

“The social cost associated with the acute localized climate burden and public health impacts induced by GDI vehicles largely overweigh their marginal global climate benefits.”

Image credit: Roland Denes via Unsplash

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