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Issues of the Environment: UM-led study shows electrification of ridesharing services to have overall benefit, with added challenges

Dr. Parth
Parth Vaishnav
Dr. Parth Vaishnav, Assistant Professor for Sustainable Systems Climate + Energy at the University of Michigan.


  • Ridesharing services have become an increasingly in-demand new mobility service in many cities. Services like Uber and Lyft are popular with college students living on campuses in Washtenaw County and people who don’t own a personal vehicle.
  • Electric vehicles are well-suited to ridesharing services because the distances the cars travel tend to be short sprints across town. The two top ridesharing companies in the world, Uber and Lyft, have pledged to transition to fully electric vehicles in the US, Canada and Europe by 2030. 
  • The move is hailed for its impact on reducing greenhouse gas emissions, but a new collaborative study by researchers at the University of Michigan and Carnegie Mellon University shows that there could be some downsides. What real-world societal and environmental benefits would electric fleets promise? The CMU and Michigan researchers conducted life-cycle comparisons based on real-world rideshare data to find out.
  • The study found that all-electric ride-hailing fleets cut greenhouse gas emissions, but increase air pollution and traffic problems. Overall, making all rideshare vehicles electric would bring a societal benefit of only 3 percent per trip on average, according to the study published in the journal Environmental Science & Technology.
  • Using data collected in the Chicago area (one of the largest ridesharing markets, averaging 300,000 daily trips prior to the COVID-19 pandemic), they used a model that combined data from over a million Uber and Lyft trips taken on weekdays, weekends, and during different seasons with detailed geospatial vehicle routing data to analyze the costs of ridesharing services in terms of greenhouse gas emissions, traffic costs, and air pollution. They compared these results for a gasoline fleet and a battery-electric fleet.
  • Rideshare vehicles drive more miles every year than personal vehicles, the researchers write, “which means that electrifying these vehicles could have greater societal benefits.” Indeed, their analysis showed that electrified fleets had 40–45 percent lower greenhouse gas costs per trip compared to the gasoline-powered vehicles. But the EVs also created slightly higher air pollution—sulfur dioxide, nitrogen oxides, and particulate matter—because recharging them relied on power from local power plants and also created more fine ground-level particles from tire and brake dust. The simulations showed that EVs had to drive farther and more frequently without passengers since they have to travel to recharge more often than gasoline vehicles have to refuel, and there are fewer charging stations than gas stations. The longer traveling distance meant they were involved in more traffic problems, including crashes, congestion and noise.
  • The study showed that higher air pollution would increase health impacts by an estimated 6–11% per trip on average. And the extra driving to and from charging stations would increase traffic-related harms by 2–3% per trip.
  • Parth Vaishnav, Assistant Professor for Sustainable Systems and Climate + Energy at the University of Michigan, points out that reducing passenger vehicle trips is a superior way to slash greenhouse gas emissions from personal transport. Another way to reduce net pollution and emissions is through car-pooling and/or increasing the number of accessible charging stations to reduce trips just to refuel. 


David Fair: This is 89 one WEMU, and welcome to this week's edition of Issues of the Environment. I'm David Fair, and perhaps you are among the many that utilize a ridesharing service from time to time or even on the regular. Services like Uber and Lyft are particularly popular in college towns and urban centers, and that includes Ann Arbor. Now, both of those companies have pledged to fully transition to electric vehicles by the year 2030, and it's easy to imagine that it would be of significant benefit to the environment. Well, there's some new data that suggests that may not be entirely the case. A collaborative study by the University of Michigan and Carnegie Mellon University suggests that while it would reduce greenhouse gas emissions, it would also increase air pollution and traffic problems. We wanted to learn more, so we're going right to the source. Parth Vaishnav is an Assistant Professor for Sustainable Systems and Climate and Energy at the University of Michigan and served as senior author of the study. And thank you so much for making time for us today, Parth.

Dr. Parth Vaishnav: Thank you very much for having me.

David Fair: When this study was launched, was there a hypothesis in place?

Dr. Parth Vaishnav: Yes. We believed that there would be a substantial reduction in greenhouse gas emissions and potentially a reduction in other kinds of pollution like all types of sulfur dioxide, all types of nitrogen and fine particulate matter, all of which damaged people's health in the short term. We thought all of that would go down because when you electrify vehicles, after all, you're moving pollution away from a density where those vehicles are applied to a power plant, which hopefully is some distance away where the population density is a bit lower.

David Fair: When the study was then constructed based on this hypothesis, what exactly did you decide was the necessary components of the study?

Dr. Parth Vaishnav: Well, the study is based on real trips that were taken by Uber and Lyft. The City of Chicago actually provides data about actual trips that took place. And so, we wanted to assess whether those trips, if they had been served by electric vehicles, would cut greenhouse gas emissions and would cut damages from other pollutants. And we also wanted to understand how electrification would affect other sources of damage and air pollution, including congestion and noise and crashes. The other thing that's kind of important because of when this study was done and when it was published was we looked at days of trips before the pandemic, during the pandemic, and after there was widespread vaccination available. So, we're actually able to understand how the effect on pollution and how the provision of ridesharing services has actually changed with the changing levels of traffic and demand for ridesharing as the pandemic evolved.

David Fair: As you analyze all of these comprehensive factors, what you're looking for is the difference in societal costs of ridesharing services for the EVs as compared to a fleet of gasoline-powered vehicles, how do you define societal costs before we get into the results?

Dr. Parth Vaishnav: Yes, we looked at societal costs in two broad categories. So, one is damages from air pollution. But this is a monetary estimate of how much damage the emissions of carbon dioxide, fine particulate matter, sulfur dioxide, and all type of nitrogen does to the human health and the environment. And the other category of damages was how much each vehicle type would contribute to added congestion, to noise, and to crashes.

David Fair: As you mentioned at the top, you expected that a lot of the air pollution factors would actually go down--that there would be a decrease. And that's not at all what you found, is it?

Dr. Parth Vaishnav: We did find that greenhouse gas emissions are nearly cut in half, but we did find that the damages from the other types of pollutants go up a little bit because of electric vehicles. So, for example, we were able to see that because charging stations for electric vehicles are more scarce than gas station,. Electric vehicles would have to drive around empty for longer in order to find these stations. And so, even if they're not serving passengers, they're contributing to air pollution. They're contributing to crashes and noise and congestion. And it turns out that, once you add up all of that and you monetize it, electric vehicles are better, but only by a smidgen.

David Fair: WEMU's Issues of the Environment and our conversation with University of Michigan Assistant Professor Parth Vaishnav continues. He is senior author of a study of a real-world comparative study of all electric ridesharing fleets and the environmental impacts that it will and won't make. When you extrapolate out the societal costs, do you consider things like wear and tear on the roads, cost of repairs, rate and number of accidents? And, of course, you've mentioned the impacts on public health. Are you putting dollar figures to those?

Dr. Parth Vaishnav: Yes, we're putting dollar figures to all of those things that you mentioned. I don't know that we're looking at the wear and tear of the road, but we're looking at congestion. And the effect of condition is traffic delays and time basis. We are looking at the increased risk of crash, and we are looking at the effect of noise. And I think the other important point that you made was that we are actually monetizing these damages, and they're using sort of a standard estimate of the amount of damage that each of these types of pollution do. And I think that is where we need to be a little bit cautious about interpreting these results. So, for example, if you decide that actually damages from greenhouse gas emissions are much greater than what we are assuming here, then you would reach a slightly different conclusion--not a dramatically different conclusion, but a slightly different conclusion. So, some of these costs--how much should society value, the damage from greenhouse gas emissions--are socially determined. So, this is something that kind of society rethink every few years, and the numbers tend to change.

David Fair: There is also a social justice component to our transportation, our pollutants, our air quality. Is social justice part of what you want to accomplish in getting this data together and providing a blueprint forward to something healthier?

Dr. Parth Vaishnav: Yes, very much so. So, one of the things that we have done here is that we have developed a model that gives us quite a lot of detail about where the pollutions occur. And I know that my colleagues are actually working on a version of this where they are able to comment on the social justice implications of what will occur. We will be able to say something about where this pollution is occurring and where the damages are felt rather than report on an aggregated number. But that is something that we're working on right now. It's not something that's in the study, but that is very much the goal.

David Fair: Once again, this is 89 one WEMU. We're talking with University of Michigan Assistant Professor Parth Vaishnav. And you've laid out many of the concerns and the challenges. Let's shift the focus to the solutions. What does the data tell you about constructing a fleet and societal transportation model that has more beneficial impact? What does that need to look like?

Dr. Parth Vaishnav: The first thing I should say is that, in the short term at least, electrification is a good idea. The aggregate benefits are relatively smaller than we would hope for, but the greenhouse gas reductions are substantial. All the benefits will actually go up as the electricity grid gets bigger. We should, in fact, electrify. This is not an argument against electrification. The second part of this is that what we're finding is that only about 20% of the damage associated with these vehicles actually comes from air pollution. The rest of it is crashes, congestion and noise. And what that tells us is that the problem is not how we energize these cars. The problem is that so much of our travel relies on private vehicles. So, one of the big messages, at least for me that comes from this, is that, yes, we should make personal transport cleaner, but we should also design cities where people are less dependent on personal transport. We should invest in transit. We should invest in active modes of transportation, like biking and walking.

David Fair: So, that leads us to a more complicated question that clearly wasn't a part of this study, but perhaps you've come across it in your observations. The kinds of changes you describe require a great deal of innovation and investment from all sectors: from government, industry, utilities and the taxpaying consumers. Is there something that you have come across that gives you optimism that we're going to put all of these sectors together to agree to make the investments and sacrifices it's going to take to create a more viably sustainable transportation sector that has more significant, beneficial environmental impact?

Dr. Parth Vaishnav: It is the case that, in the last few years, the current federal administration has invested considerable sums of money in transit. There's been unprecedented investment. And so, I am optimistic that, certainly at the federal level, government gets it. That it needs to do it. There's also an expansion of biking lanes and biking infrastructure. I know some of that is happening in Chicago--

David Fair: It's certainly happening in communities here in Washtenaw County.

Dr. Parth Vaishnav: Absolutely right. And this is something that people are demanding. If you look at the uptake of schemes where people are offered e-bikes, schemes are massively oversubscribed. So, there is a hunger for these kind of solutions. And I don't know that people necessarily view some of these things as a sacrifice. I think people recognize that it is unpleasant to drive in congested cities. Maybe it is better for the environment and for our health if we use active modes of transportation. Maybe it's better for the vibrancy and safety of our cities if we use different modes of transportation. So, I don't know that people see this necessarily as a sacrifice. It's a matter of making sure that people have options that allow them to exercise these choices while still being able to work productively where they like and when they like.

David Fair: That is Parth Vaishnav. He is an Assistant Professor for Sustainable Systems and Climate and Energy at the University of Michigan. Issues of the Environment is produced in partnership with the office of the Washtenaw County Water Resources Commissioner, and we bring it to you every Wednesday. I'm David Fair, and this is your community NPR station, 89 one WEMU FM Ypsilanti.

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