Updated: Oct 10, 2022
by Tim Donovan
As EVs become more mainstream, this question of whether they are truly better for the environment comes up more frequently. The logic goes something like this: Since we live in Ohio (or substitute your locale), and Ohio gets most of its electricity from gas and coal, aren’t EVs just as dirty as gasoline powered cars?
It’s logical to ask and the answer may surprise you.
Yes, power grids still use dirty energy
According to the latest national figures from the U.S. Department of Energy, renewables (wind, hydro, solar, and biomass) make up about 19% of our total electricity generation. That leaves the current mix of fossil fuels and nuclear energy covering the remaining 81% of the energy generated. Here in Ohio, the amount of energy generated by just coal, gas, and nuclear jumps to over 96%!
The data clearly shows we don’t have the cleanest power in Ohio. So how does that translate to EV drivers, many of whom switched to an EV because of the perception that they are “cleaner” and better for the environment?
The CO2 impact of cars
One of the ways we can measure this is through the amount of carbon dioxide (CO2) emitted through a year of driving. We know that the tailpipe CO2 emitted from burning one gallon of gasoline is 8,887g and that translates to about 404g of CO2 per mile. This works out to about 4.6 metric tons of carbon dioxide per year for gasoline cars no matter where you live in the US.
Given our mix of fuel in the electric grid in Ohio, what does it look like for Ohio electric car drivers? As a reminder, renewable energy makes up a tiny fraction of energy generated in Ohio.
Even with Ohio’s fossil fuel heavy mix, electric vehicles only “emit” 2.6 metric tons of carbon dioxide per year. That represents a little over half of the CO2 of gasoline cars. That’s a pretty significant reduction just from filling an EV with energy from the grid. If you are able to plug your EV directly to solar power either at your home or at a facility like the Cincinnati Zoo’s parking lot, that number drops to ZERO tons of carbon dioxide!
More than just CO2
Looking just at CO2, there is a big environmental advantage to EVs over gas and diesel powered vehicles. But there are other tailpipe emissions besides CO2. Gasoline powered vehicles also produce methane (CH4) and nitrous oxide (N2O) from the tailpipe and while these emissions are smaller than the CO2, they are still significant. When looking at the transportation sector as a whole, it represents 14% of global greenhouse gas emissions. Almost all (95%) of the world's transportation energy comes from petroleum-based fuels, largely gasoline and diesel, although that is undergoing a rapid transformation to electric vehicles.
The bottom line is that electric vehicles represent a big opportunity to reduce greenhouse gas emissions and as the electric grid continues to change its fuel mix from fossil fuels to renewable energy, the environmental benefits will only continue to grow.