Scooters are tops, buses are among the worst, at least when it comes to limiting greenhouse gas emissions over the life cycle of all possible commuting options.
That’s the shocking news from a study pending from Colorado State University researchers, and no doubt a disappointment to cranky city dwellers tired of jumping over or around tipped-over scooters abandoned after their batteries died.
Electric scooters take relatively few resources to produce and carry residents efficiently over short distances, sharply limiting their greenhouse gas contributions as they get the job done — just before expiring at crucial crosswalks.
Buses are great — when full. But the average bus trip only has seven or eight passengers, making a commuting journey on a diesel-powered bus one of the least efficient per-passenger-mile methods when greenhouse gases are accounted for, according to CSU engineering researcher Noah Horesh.
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And what does the study have against walking? According to the charts compiled by Horesh and mechanical engineering professor Jason Quinn, our assumption that a human stroll is the healthiest option for the planet may be far too simplistic.
For the energetic walker, the problem is the eating involved. Americans in particular have a meat and processed food-heavy diet that creates a lot of greenhouse gas emissions in producing the food needed to fuel a good walk.
And walking isn’t kinetically efficient, no offense to pedestrians, Horesh adds. Those two facts put the “life cycle” emissions per passenger-mile for a walking trip right up there with a mostly empty bus, Horesh says.
“Basically, electrified transportation can get pretty close to zero”
Now that doesn’t mean we should give up walking or electric cars, or that we all should get the scooters the cool kids use. As a percentage of overall emissions, fossil fuel powered cars are still the monsters in producing greenhouse gases. Transportation accounted for 29% of overall greenhouse gas emissions in the U.S. in 2021, the study says.
It’s more vital than ever to switch cars and buses to efficient electric batteries and motors, the study concludes. And for policymakers to expand clean mass-transit options, and then for commuters to use them.
“The greatest emissions reductions can be achieved through adopting technologies energized by decarbonized electricity and changing travel behavior,” according to Horesh and Quinn, who are preparing to publish the study in a reviewed journal.
Even electrified transport can never be pure, Horesh said in an interview, because it appears impossible to eliminate all the emissions associated with constructing an electric vehicle. But, he said, “Basically, electrified transportation can get pretty close to zero.”
The chart can be useful to the individual and society at large in making transportation decisions, Horesh said.
For the personal commuter, it’s not just a matter of feeling guilty about choosing a car over a scooter. Not everyone has the freedom or the time to travel with greenhouse gas as the only consideration. If people do have options, Horesh said, think of it this way: The bus or other form of mass transit is a great choice for the planet because it’s already scheduled to make that trip on that route. Adding yourself as a passenger immediately moves that bus up the chart.
“You don’t have any marginal emissions associated,” Horesh said. “The best thing is to go on a trip that’s going to happen no matter what.”
For people with the means or enough rebates in hand, choosing to buy an electric vehicle over a fossil fuel car would seem an obvious good choice, emissions-wise, right?
It depends, according to the new study. Because of the extra materials and inefficiencies that go into making a car with a big battery stack, the lifecycle emissions of that vehicle only win out after 25,000 miles are driven, Horesh said. And keep hybrids in mind — the increasingly popular vehicle option that combines a smaller electric battery with an internal combustion engine.
Because hybrids are more efficient to produce, a buyer would have to use a fully electric car for 55,000 miles before achieving the lifecycle greenhouse gas efficiency of a hybrid car, Horesh said.
“So if someone’s not going to drive their vehicle much, it would be better to get a hybrid,” he said.
The researchers said they try not to edge toward dictating social policy, but some of the implications of their study are fairly obvious. For short commutes, other studies show that people are more inclined to use efficient scooters, e-bikes or traditional mechanical bikes to get to work if there are dedicated lanes and other safety measures.
“So enabling some of these technologies that have lower emissions, and being less reliant on cars,” Horesh said.