One of the most popular strategies for reducing dependence on fossil fuels is to “electrify everything.” That’s because even with today’s energy mix in the United States—according to the Energy Information Administration, 61% of electricity generation was from fossil fuels—electric cars and light trucks still have far lower emissions than their gasoline-powered equivalents.
But they still do have emissions, from both the generation of the electricity that powers them and the upfront carbon emissions released during the manufacture of the vehicle.
This is why we have often written that three things are needed for the electric revolution: reduce demand. clean up electricity, and electrify everything. In houses or cars, size and efficiency still matter because there are only so many clean kilowatts out there and they are unevenly distributed.
Writing for the American Council for an Energy-Efficient Economy (ACEEE), transportation analyst Peter Huether looked at the question of efficiency in an article titled “9,000-Pound Electric Hummer Shows We Can’t Ignore Efficiency of EVs” He compared a small electric car to the Hummer:
“The Chevy Bolt EV is responsible for about 92 grams of carbon dioxide (CO2) per mile when accounting for emissions from the electric grid. (The CO2 calculations are based on the national average, but electric grid emissions vary considerably across the country.) The gasoline-powered Chevy Malibu causes over 320 grams per mile. Comparing larger vehicles, the original Hummer H1 emits 889 grams of CO2 per mile and the new Hummer EV causes 341 grams, demonstrating that behemoth EVs can still be worse for the environment than smaller, conventional vehicles.”
And this is without even considering the upfront or embodied carbon emissions from making the vehicles. It’s just straight carbon dioxide (CO2) out of the smokestack instead of the tailpipe. Huether noted these matter too:
“The environmental impact of EVs isn’t just about the electricity generated to power each mile. The manufacturing process also causes the release of greenhouse gases at several stages, known as the embodied emissions of the vehicle. EVs in particular—with heavy battery packs—use minerals that need to be mined, processed, and turned into batteries. The pursuit of greater driving range and larger vehicles requires increasing battery size, also increasing embodied emissions.”
Huether called on the Environmental Protection Agency to develop efficiency standards for electric vehicles: “All EVs do not have the same impact on the environment, and our vehicle regulations should reflect that.” The efficiency is a function of weight and aerodynamics, with smaller and lighter vehicles being more efficient.
But even among vehicles of the same weight, there can be significant variations; in the 5,000- to 5,500-pound range of weights, efficiencies range from 25kWh/100 miles to nearly 48 kWh/100 miles, just under half as efficient. The Electric Hummer needs 62 kWh to go 100 miles; that is a lot of juice, enough to run the average American home for two days.
Huether concluded we need regulations and standards, just as there are for gasoline-powered cars, with greater emphasis on efficiency. He wrote, “Greater EV efficiency can reduce emissions from driving and manufacturing the vehicles and increase range and reduce costs.”
GMC
Huether is not alone in questioning the need for such big inefficient vehicles. The Drive‘s James Gilboy and Peter Holderith make many of the same points about how efficiency matters. “Lower efficiency means charging more often. Charging more often means more energy consumption,” wrote Gilboy and Holderith. “You can see where this is going.”
They also do a great explanation of the importance of embodied carbon, one of the first I have seen applied to cars outside of Treehugger. They noted companies are not revealing the upfront carbon data—only Volvo does with the Polestar. They extrapolated from the Polestar to actually try to estimate the upfront carbon for the Hummer EV, coming up with 50.6 metric tons, which is “more than triple the 15.2 metric tons of CO2 emissions Americans averaged in 2018.” This is another important milestone, where they demonstrated how important embodied carbon is and made it relatable.
They concluded:
“There are two main takeaways from all this. One, simply being an EV is not enough to be sustainable. Electric trucks do represent a long-term improvement over pure combustion and even hybrid trucks if they can stay on the road, but their resource-intensive manufacturing and sheer size make them less green than smaller gas-powered cars. And two, while we’ve been able to use what little data we have to better understand the effects of electrification, the lack of information from most OEMs we contacted demonstrates the auto industry has a transparency problem we’d do well to start taking seriously.”
In the end, there is no question that every electric vehicle is a dramatic improvement over its gasoline-equivalent. But just as in gasoline-powered vehicles, size, weight, and efficiency matter for both upfront and operating carbon emissions. And that Hummer is a climate-killer—no matter what it runs on.
