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Common Tread

Are electric motorcycles really better for the environment?

Mar 03, 2020

Skeptics of electric vehicles often ask whether EVs are really better for the environment, considering that the U.S. grid still generates a lot of electricity by burning coal and natural gas. That’s why I was interested to read a recent Union of Concerned Scientists blog post by David Reichmuth.

Reichmuth — the UCS’ Senior Vehicles Engineer — recently crunched two data sets to conclude that the average American EV driver is responsible for global warming emissions equivalent to driving a car that gets 88 miles per gallon. That’s an almost impossibly high mileage target for any mass-produced internal combustion vehicle. (The most efficient gasoline car sold in the United States gets 58 mpg. Factoring in trucks and SUVs, the average new vehicle sold last year got only 21 mpg.)

To come up with that 88 mpg figure, Reichmuth matched EV efficiency data with regional electrical power production emissions data. He concluded: “When looking at all these factors, driving the average EV is responsible for fewer global warming emissions than the average new gasoline car everywhere in the US. In some parts of the country, driving the average new gasoline car will produce four to seven times the emissions of the average EV.”

One of the most interesting aspects of this post is a U.S. map that illustrates how widely EV "emissions equivalence" varies from place to place. In upstate New York, the grid draws almost all of its electricity from hydro-electric dams in Quebec. So an EV driver in Albany is responsible the emissions equivalent of a gasoline car that gets 231 mpg.

The Kahe Point power plant on Oahu, Hawaii. As those huge storage tanks imply, this is an oil-burning facility. Although Hawaii has committed to converting its grid to 100 percent renewable energy, for now the Islands remain very dependent on imported fossil fuels. Photo by Travis.Thurston.

At the other extreme, there’s Oahu, where virtually all the electricity is produced by burning oil. An EV driver there is responsible for the same emissions he’d produce by driving a car that gets 37 mpg (or riding a Harley in Hawaii.)

There’s a swath in the upper Midwest where many power plants still burn coal and natural gas. So in much of Illinois or Wisconsin, charging up your EV results in the same emissions as driving a gasoline car that gets 39 to 40 mpg.

So in the limited defense of EV skeptics, there are some places where where the indirect greenhouse gas emissions created by EV drivers compare to the direct emissions of very efficient internal combustion autos (or the average motorcycle, or scooter).

That said, 94 percent of American EV drivers live and commute in regions where operating an EV results in fewer emissions than vehicles that get 50 mpg.

California, which has by far the largest number of EVs in circulation, also has a grid that produces 50 percent of its electricity from hydro, nuclear, wind, and solar power. Those power plants produce no global warming emissions in operation. Frustratingly, this means those smug EV drivers clogging up the HOV lanes in Los Angeles really are saving the planet. If you want to claim that your internal combustion car or motorcycle is just as green, you’ll need to get 122 mpg! In summary, EVs are responsible for far less greenhouse gas emissions than almost any car (or motorcycle, for that matter).

What about electric motorcycles?

The Union of Concerned Scientists didn’t concern itself with either gasoline or electric motorcycles. There are so few of them in use that we’d just be a rounding error in the larger study. But for what it’s worth, while EV autos are a better for the environment from a greenhouse gas perspective, electric motorcycles are much better still.

The easiest way to compare energy use of EV autos and motorcycles is to look at their respective MPGe ratings. The "Miles Per Gallon equivalent" metric was introduced by the EPA in 2010 to compare the amount of energy consumed between alternative-fuel vehicles, as well as to compare alternative-fuel vehicles to traditional gas-powered ones.

According to the U.S. Department of Energy, the Tesla Model 3 Range Plus is the most efficient commonly available EV auto. It puts up impressive MPGe figures of 148 city/142 highway for a combined figure of 141 MPGe.

But Zero’s MPGe claims put Tesla to shame. The SR/F, for example, gets a claimed 430 city/219 highway for a combined 313 MPGe.

Tesla 3
The tidy rear end of this Tesla Model 3 is the secret to its low coefficient of drag. Tesla photo.

As a side note, unlike internal combustion vehicles, EVs get higher city mileage because they regenerate some electricity when slowing down in stop-and-go situations. On the highway they’re just pushing air out of the way with no chance to recover energy lost to aerodynamic drag. That’s true for both the Tesla and the Zero, although the difference is far more pronounced for the motorcycle. That’s because the Tesla Model 3 has a remarkable drag coefficient of just 0.23. I don’t have a specific figure for the SR/F but even the most aerodynamic racing motorcycle with a rider in a full tuck has a Cd of about 0.6!

A back-of-the-envelope calculation shows me that in California (where the grid’s about 50 percent carbon-neutral, and most Zero motorcycles are sold) Ms. Green on her new SR/F is indirectly responsible for only 7.7 percent of the greenhouse gas emissions that are spewing out of Joe Blow cager’s tailpipe. According to the Department of Energy, the average motorcycle gets about 44 mpg, so even the average ICE motorcycle is responsible for about six times the emissions of Ms. Green’s Zero.

In upstate New York, where it’s running on clean Canadian hydro power, a Zero is responsible for less than 10 percent of the emissions from the average motorcycle. That’s an extreme case but but if you scroll down to the map on the blog post, here’s a rule-of-thumb: You can safely double any region’s "EV Emissions as Gasoline MPG Equivalent" figure and assume that’s the emissions equivalent for a Zero SR/F in that region. You’ll quickly see that in most of the United States, an electric motorcycle produces emissions that can only be matched by a magic internal combustion motorcycle that runs on unicorn farts.

Zero SR/S
As cool as this Zero SR/F is, like most other motorcycles it has the Cd of a dump truck. That accounts for the huge difference between its city and highway MPGe ratings. Zero Motorcycles photo.

Even on Oahu, where a Zero is charged with electricity generated by burning diesel fuel, it’s responsible for less greenhouse gas production than almost any conventional motorcycle or scooter. An ICE vehicle would have to get well over 70 mpg to come close.

The other positive factor is that the emissions impact from electric vehicles will continue getting better as the grid itself gets greener. In 2009, 45 percent of U.S. power generation was from coal. By 2018, that figure had fallen to 28 percent. Over the same period, the share of wind and solar power increased from two percent to eight percent. The effects are not trivial. In just two years, between 2016 and 2018, greenhouse gas emissions from U.S. power plants fell five percent.

Not all the environmental news is positive

In writing his blog post, Dr. Reichmuth relied on the Argonne National Laboratory’s sophisticated GREET environmental modeling technique when estimating the emissions equivalents for electric vehicles. That’s the best available model, and it factors in the emissions created when making the vehicles. But the long-term environmental impact of a wholesale shift from internal combustion vehicles to EVs is fraught with perils, including some we can’t accurately foresee.

If projections of future EV sales are accurate, battery makers will need to find, extract, and refine far greater quantities of lithium, cobalt, and other minerals. Lithium is a pretty common resource, but extracting a ton of it uses 500,000 gallons of water.

Most of the world’s known cobalt reserves are in the Democratic Republic of the Congo, which is arguably the world’s most ironically named nation — an environmental and workers’-rights fiasco.

wind turbine
The first generation of these giant turbines has already reached the end of its useful life, and it turns out these huge blades are almost impossible to recycle. Public domain photo.
One way to limit the environmental and human costs from barely regulated mining operations would be to recycle lithium-ion batteries. But a recent article in the respected science journal Nature outlined the many challenges of doing that safely and economically.

And that’s just the batteries. As more and more EVs need charging, the grid itself will be strained. Decarbonization is great, but the first generation of giant wind turbines have already reached the end of their useful lives. According to NPR, over 720,000 tons of blade material will need to be disposed of over the next 20 years. If you can believe it, there’s almost no practical way to recycle those giant fiberglass blades.

I didn’t purposely end this essay on a downer. Global warming is only one environmental problem, but it’s perhaps the most urgent. For most Americans, commuting on foot or by bicycle is somewhere between impractical and impossible. In many places, public transit’s not an alternative. It’s useful to understand your low-carbon personal transportation options.

There are many factors to consider if you're thinking about buying an electric motorcycle, but at least in terms of emissions, you can breathe easy knowing they are far greener than any internal combustion vehicle.