Researchers from the University of Michigan and Ford Motor Company found that light-duty, battery electric vehicles (BEVs) have approximately 64 percent lower cradle-to-grave life cycle greenhouse gas emissions than internal-combustion-engine vehicles on average across the United States.
This news comes as major automotive manufacturers in the US are ramping up the production of electric trucks as a key strategy to reduce the greenhouse gas emissions of their fleets. Light-duty vehicles, including saloons, SUVs and pickup trucks, are currently responsible for 58 percent of US transportation sector emissions.
Pickup trucks accounted for 14 percent of light-duty vehicle sales in the United States in 2020 and the market share of both pickups and SUVs has grown massively in recent years.
Greg Keoleian, Professor at the U-M School for Environment and Sustainability and director of the U-M Center for Sustainable Systems, said: “This is an important study to inform and encourage climate action.
“Our research clearly shows substantial greenhouse gas emission reductions that can be achieved from transitioning to electrified powertrains across all vehicle classes.”
Cynthia Williams, global director of sustainability, homologation and compliance at Ford, said: “This study can help us to understand the potential impact of electrification from an emissions-reduction perspective, particularly as we introduce new electric vehicles, and how we can continue to accelerate our progress towards carbon neutrality. We’re proud to partner with U-M in this critical work.”
In the study, researchers conducted a cradle-to-grave life cycle assessment of pickup trucks and compared the implications of pickup truck electrification to those of sedan and SUV electrification.
With a focus on evaluating greenhouse gas emissions, researchers looked at three different model year 2020 powertrain options; internal combustion engine (ICE) vehicles, hybrid-electric vehicles and battery electric vehicles—for midsize sedans, midsize SUVs and full-size pickup trucks. They looked at differences in fuel economy, annual mileage, vehicle production and vehicle lifetime across vehicle classes.
Researchers found that switching an internal combustion engine vehicle to a battery electric vehicle results in greater total tonnage of emissions reductions as the vehicle size increases, due to the greater fuel consumption of larger vehicles.
Max Woody, study first author and Center for Sustainable Systems research specialist, said: “Though the percentage savings is approximately the same across vehicle classes, on average replacing an internal combustion engine saloon with a battery-electric sedan saves 45 metric tons of carbon dioxide equivalent.
“Replacing an internal combustion engine SUV with a battery-electric SUV saves 56 metric tons of carbon dioxide equivalent, and replacing an internal combustion engine pickup with a battery electric pickup saves 74 metric tons carbon dioxide equivalent over the lifetime of the vehicles,”
The researchers also found that battery-electric vehicles have larger greenhouse gas emissions in their manufacturing than internal combustion engine vehicles. This is due to battery production but this impact is offset by savings in their operation.
For battery-electric vehicles and internal combustion engine vehicles, the breakeven time is 1.2 to 1.3 years for saloons, 1.4 to 1.6 years for SUVs, and 1.3 years for pickup trucks, based on the average US grid and vehicle miles travelled.
Vehicle emissions vary across the country because different temperatures and different drive cycles affect a vehicle’s fuel economy. For electric vehicles, the emissions intensity of the local electricity grid is also an important factor.
The study developed maps to show the lifetime grams of carbon dioxide equivalent/mile for each powertrain and vehicle type by county across the United States.
Researchers found that concerns about battery electric vehicles having higher emissions than internal combustion engine vehicles or hybrids are largely unfounded.
This is because battery electric vehicles outperform hybrids in 95 percent to 96 percent of counties, while battery electric vehicles outperform internal-combustion-engine vehicles in 98 percent to 99 percent of counties, even assuming only modest progress towards grid decarbonisation.
Charging strategies can further reduce battery-electric vehicle greenhouse gas emissions. The study found that charging during the hours of the day with the lowest grid emissions intensity can reduce emissions by 11 percent on average.
Woody added: “Deployment of electric vehicles and expansion of renewable energy resources like solar and wind should be done at the same time; the benefit of each is increased by the development of the other.”
