Research suggests that electric vehicles are no silver bullet against global warming. The Inflation Reduction Act (IRA) will allocate more than $15 billion in credits and loans for electric vehicle and battery manufacturers, as well as tax credits for buyers of electric vehicles. The stated rationale: these cars produce fewer carbon emissions than cars with internal combustion engines. But recent research shows that this may not always be true.
Consider an April paper published in the SAE International Journal of Electrified Vehicles by a team of engineers and data scientists. The paper compares greenhouse gas emissions from plug-in, battery-powered electric vehicles with emissions from hybrid vehicles, which combine internal combustion engines with small battery packs. The conclusion: pure plug-in battery-powered vehicles can create more emissions than hybrids and even some traditional internal combustion engine vehicles–whose fuel delivery, air delivery, and ignition systems have improved over the past 20 years, increasing overall vehicle gas mileage.
Electric cars don't have tailpipe emissions, but their batteries are charged using electricity. And electricity production–unless it's from renewables, hydropower, or nuclear energy–results in carbon emissions. The authors cite data from the Energy Information Administration, which show that the proportions of electricity sources typically activated and deactivated to match demand often bear little resemblance to the proportions for total electricity generation. To minimize emissions and cost, electricity grids tend to use clean sources such as nuclear, solar, and wind as much as possible. But demand often exceeds what these sources can provide, making "marginal sources" that respond immediately to demand–hydropower and fossil fuels–necessary.
Most studies of emissions use average emissions rates–the rates from the total proportions of electricity generation. But these rates include zero-emission sources that are not available to meet increased demand, meaning that average emission rates are artificially low in most of the United States. Added electricity demand from the rapid adoption of all-electric vehicle fleets could therefore move the economy further away from the point where most of the demand can be met by low-emission sources.
What about fuel-powered hybrid vehicles? These recover energy from the braking system and use it to supplement smaller internal combustion engines. The study's model finds that they produce fewer emissions today than electric vehicles in most of the United States. Only the most optimistic projections of U.S. grid cleanup suggest electric-vehicle emissions superiority, even with an 18-year electric-vehicle life. Unfortunately, these hybrids will not qualify for new electric car credits, because they are not plugged into charging systems.
As the authors note, decarbonizing electricity production would change the emissions calculus. "A mix of powertrain technologies is the best path toward reducing transportation sector emissions until the U.S. grid can provide electricity for the all-electric fleet infrastructure and vehicle operations with a carbon intensity that produces a net environmental benefit," conclude Tristan Burton, Cooper Burns, and Kelly Senecal of Convergent Science; Graham Conway of the Southwest Research Institute; Felix Leach of Oxford University; and Scott Powers of the Houston Astros. Nuclear power would be revolutionary because it generates substantial amounts of emissions-free electricity, but nuclear plants take years to build and add to the grid. The IRA contains $30 billion in tax credits over the next ten years for nuclear-power subsidies.
In any case, electric vehicles have practical problems. Drivers pay more for less-convenient mobility: Ford's F-150 Lightning electric pickup truck costs $46,974, compared with a base price of $32,000 for a traditional model. GM, Tesla, and Rivian have hiked the prices of their electric models. Meantime, batteries and electric-car components usually come from China, where they're made with coal-fired electricity. To reduce dependence on China and minimize fossil-fuel use globally, the IRA restricts electric vehicle credits to cars made in the U.S. that source their battery components from North America. That provision may bring some future production to the United States, but substantial manufacturing cost differentials between America and China will likely remain. For now, most electric cars won't qualify for the law's tax credits.
Attempts to lower emissions in the United States shouldn't overlook this research. Focusing on battery-powered electric vehicles may neglect more fruitful means of emissions reduction. As the researchers write, "the future is eclectic, not electric."