Both Uber and Lyft have committed to fully electrifying their vehicle fleets in the United States by 2030.
The move would eliminate exhaust pollution while shifting emissions to the power plants that provide electricity to charge electric vehicle batteries, likely resulting in a significant drop in overall emissions of climate-warming greenhouse gases.
All good news, right? Hold onto.
A new study by researchers from the University of Michigan and Carnegie Mellon University estimates that the overall benefits to society from switching ride-hailing services from gas to electric vehicles would be very modest — on average, a 3% gain per trip at the cost of others “. Society” is taken into account.
Those societal costs include increased traffic congestion, collision risk and noise due to Uber and Lyft drivers commuting to and from fast-charging stations, according to the study published online June 1 in the journal Environmental Science & Technology.
“Our simulation showed that electric vehicles travel longer distances without a passenger than gasoline vehicles because electric vehicles need to drive to chargers more often than gasoline vehicles need to refuel,” said the study’s lead author Parth Vaishnav, an assistant professor at the UM School of Environment and Sustainability.
“Also, fast chargers are not as ubiquitous as gas stations, which means electric vehicles have to travel a longer distance than petrol vehicles for each fill-up.”
In their simulation, the researchers used a new high-resolution model called AgentX with real-world Uber and Lyft ride data collected from 2019 to 2022 in the greater Chicago area. Chicago is one of the largest ride-hailing markets in the country, with daily rides averaging around 300,000 before the Covid-19 pandemic.
The researchers modeled more than a million Uber and Lyft rides across weekdays, weekends and different times of the year. This included travel undertaken prior to the onset of the pandemic, as well as travel undertaken in the aftermath of the full rollout of vaccines.
A number of standard economic instruments have been used to express the cost to society in dollars. Although the study results are specific to Chicago, the researchers say the results likely apply more generally.
The study found the following:
- Electrification of Chicago’s ride-hailing fleets would reduce lifetime greenhouse gas emissions by 40-45% compared to gasoline-powered vehicles. The decline is mainly due to the higher efficiency of electric vehicles.
- Due to the higher concentrations of local pollutants (such as sulfur dioxide, nitrogen oxides and particulate matter) from fossil fuel power plants, the health impacts of local air pollution would increase by an estimated 6 to 11% on average per trip.
- Additional trips to and from charging stations would increase the traffic-related damage to society (traffic jams, risk of accidents and noise) by 2-3% per trip.
- Overall, full electrification of ride-hailing would reduce the overall damage to society by about 3% per ride.
- A 3% reduction in societal costs saves the City of Chicago approximately $1.5 million per year. To put that number in perspective, it’s estimated that ride-hailing in Chicago generates $4-5 million in revenue per day.
“It may seem counterintuitive that the overall cost to society decreases so little despite the significant reduction in greenhouse gas emissions from the shift to electric vehicles,” said the study’s lead author Aniruddh Mohan, a former graduate student at Vaishnav at Carnegie Mellon and now a postdoctoral fellow from Princeton University.
“Measured per mile, however, greenhouse gas emissions represent a very small part of the total cost to society of these vehicles. When it comes to costs, external traffic effects – congestion, risk of accidents and noise – dominate, which correlate directly with the distance traveled by the vehicle. And the distance traveled by vehicles will increase with electrification.”
About 80% of the total cost to society is due to transport-related factors, while 20% is due to emissions, the study said.
The assessment includes the total cost to society of building, operating and disposing of electric and gas powered vehicles. These lifetime costs include battery manufacturing, gasoline refining, and vehicle construction.
For electric vehicles, researchers looked at battery size and how it affects vehicle impact. Manufacturing smaller battery packs requires less energy and results in lighter vehicles, both of which could result in savings in greenhouse gas emissions.
To her surprise, smaller batteries didn’t help. According to the study, a smaller battery meant EV drivers sought out chargers more often, and those extra miles offset the emissions gains from using a smaller battery.
“Overall, our results have made it very clear that a large proportion of the damage caused by cars is unrelated to their air emissions and therefore unlikely to be eliminated by electrification,” Vaishnav said.
“Electrification is a small gain for society. A bigger achievement would be to drastically reduce our dependence on cars. Policies that reduce the distance traveled by vehicles through investment in public transport and infrastructure for cycling and walking, or reduce the risk of accidents through improved vehicle safety are crucial.”
Authors of the study, along with Vaishnav and Mohan, are Matthew Bruchon and Jeremy Michalek of Carnegie Mellon University. The work was supported in part by a grant from the Wilton E. Scott Institute for Energy Innovation at Carnegie Mellon University.