What are the Hidden Environmental Costs of Electric vs. Gas Cars?

Electric vehicles are largely seen as an environmental good and a tool for slowing climate change. But are electric cars (EVs) really as environmentally friendly as we think?

All-electric vehicles, hybrids, and hybrids emit very low or zero exhaust gases. That means virtually zero greenhouse gas emissions produced by the vehicles themselves—definitely a good thing for the environment. However, there are other factors that influence the amount of pollution generated by your electric vehicle. These include the location of your local power grid, how often you charge your battery, the climate around you, the battery manufacturing process, your driving patterns, and where your electricity comes from.

The above five factors all affect an EV’s performance—and how much, if any, of a negative environmental impact it has. Let’s examine each one in turn. 

1. Sources of Electricity

Electric cars generate energy via electrochemical reactions in their lithium-ion batteries, which doesn’t require burning fuel the way a gas-powered car does. The only thing that runs on battery energy is electricity. Hybrids are low-demand hybrids that use a battery while driving in cities, but still run on gas. Most hybrids and EVs also have some kind of regenerative braking, which uses kinetic energy to charge the vehicle’s battery and further increases its efficiency.

The elimination of polluting power sources like oil and coal should be a priority.

However, electric vehicles generate emissions in a slightly different way. The power plants supplying energy to the grid we use to charge those vehicles can produce harmful greenhouse gas emissions if they’re powered by burning fossil fuels. Areas in the Midwest region of the United States still rely on coal plants that have proven environmentally harmful for producing electricity. The West Coast has a more renewable-heavy mix. They draw on solar and wind to power more of their grid, but still rely on fossil fuels in some areas.

For EVs to fully reach their potential as “clean” vehicles, we need to restructure the grid. It is important to eliminate polluting power sources like coal and oil in favor for renewables. EVs could still emit harmful gases if the electricity they consume is generated from burning fossil fuels. But make no mistake: Even when using non-renewable electricity, they still generate less carbon over their lifespan than gas vehicles.

Tesla Model 3

Some also argue that taking emissions off roads near houses and businesses does reduce harmful air pollution, even if power plants are located away from cities and people are still producing greenhouse gases. A cleaner grid could make air pollution less harmful. The UK, for example, has reduced carbon emissions from electricity generation by almost 40% in the past three years, according to the UK climate publication Carbon Brief. France and Norway both get most of their energy from renewable sources, such as nuclear and hydroelectric power. In countries with this kind of energy mix, the production of EV batteries (which we’ll get to later) is the most carbon-heavy part of an electric vehicle’s existence.

2. Time of Day When Charging

Some areas of the US use different energy sources at different times of the day. In Chicago, Philadelphia, and Washington D.C., coal-fired power plants are used at night. While this reduces monetary energy costs and increases pollution, it also makes the environment more efficient. Charging during daylight, when power comes from cleaner sources, could help to reduce emissions. 

This could mean charging at a public station outside your home or in a garage, if one is available. Many people charge their EVs at home overnight so this may not be an option for many EV owners. It also isn’t a sustainable model for the long term. This problem can be corrected by making the grid more green. 

3. Local Climate

Extreme heat and cold have negative effects on the efficiency of electric vehicles. EVs in more extreme climate areas in the U.S. can use up to 15% more energy on average, according to Carnegie Mellon University’s Department of Engineering and Technology. In the very coldest areas, it can be as much as 40% more energy use. Cold weather slows down chemical reactions in the lithium-ion battery that powers all-electric cars. It also requires more power to power auxiliary electrical systems like heating. If power is derived from fossil fuel-burning power plants, the extra energy used could lead to higher emissions.

But EV battery technology continues to improve. Battery packs that take less time to charge and are more energy-dense are in development. Cooling systems are already installed in EVs to reduce the heat damage caused by extreme heat. 

4. Battery Manufacturing

Battery and vehicle manufacturing are the most emissions-heavy processes involved with an EV. Around half the lifetime emissions from an EV’s battery come from the electricity used in its manufacturing and assembly, according to the Swedish Environmental Institute.

There’s also the matter of the metals that go into those batteries, such as cobalt and lithium. These metals have to be mined out of the earth through processes that are anything but green. In fact, mining the materials for an EV battery and assembling it produces more emissions than the production of a gasoline car. The processes involved in mining rare earth metals are water-intensive and can be harmful to the surrounding environment, wildlife, and people. 

EVs are still more polluting than gas vehicles, even after calculating their lifetime emissions. While gas vehicles emit more harmful emissions with age, EVs can be kept for many years and still have a low emission level. The most polluting part is battery manufacturing.

Image: The Union of Concerned Scientists

EV battery recycling is another area of environmental concern. It’s currently very difficult to extract the metals from a battery at the end of its life and use them in the construction of new ones, and the process is energy-intensive. That could be why a 2019 Chemical and Engineering News report puts the number of lithium-ion batteries currently being recycled at under 5%. 

The report does contain some encouraging news. Due to the popularity and increased use of lithium-ion battery technology, more effort is being made to find ways to recycle them. The U.S. Department of Energy (DOE) launched a $5.5 million reward program to incentivize methods of collecting and storing old batteries in 2019, and it’s currently in the final phase.

Other uses for battery packs that can no longer power an EV are being explored. They could be used to store electricity for home backup, or they could be used as an alternative power source for less-energy-intensive devices.

A good recycling program would reduce the need for new ore mining, which would in turn reduce the negative environmental impacts of mining.

Auto manufacturers like VW are developing ways to recycle up to 97% of a used battery’s component metals for use in new batteries. A good recycling program would reduce the need to mine ore. This would also reduce the negative environmental effects of mining. Old batteries acting as a larger source of new metals would mean more of that ore stays in the ground, slowing down the depletion of the existing supply. A recycling program that is efficient for EV batteries would help to address one of most detrimental environmental aspects of EV manufacturing. 

Mazda MX-30

5. Driving Patterns

Whether an EV is used mostly for city or highway driving is another determining factor in their environmental cost. Studies have found that in city driving conditions, EVs and other electrified vehicles like hybrids have the potential to drastically cut emissions and save drivers money over their lifetime compared with conventional cars—especially in stop-and-go traffic. On the highway, however, EVs were only marginally more efficient than gas cars in reducing emissions and costing more.

The study’s authors say this data is hard to nail down conclusively because factors such as driver behavior and non-representative samples can affect results in ways that might reduce accuracy. 

So, are EVs really green?

It depends. If EVs are constantly charging on a grid powered by fossil fuels, then they aren’t doing as much for the environment in the long run as they could, even if they don’t release emissions from their tailpipes. If EVs are to be adopted as the main mode of transportation, we must address issues such as battery manufacturing and environmental damage from mining component metals.

EVs have a lower environmental impact than gasoline cars over their lifetime. This impact will only decrease. A grid that is more powered by renewable energy sources will, along with a battery recycling program and improvements in battery technology, make EVs the green machines that we all envision. While we have made progress toward these ends, we still have a long way to go.

But EVs by themselves will not save us from climate change, and they won’t be the only green transportation solution we need. They are certainly helpful, but they can be improved to reduce their impact. To see a significant reduction in harmful greenhouse gas emissions and pollution, we as a society must develop EVs along with efficient public transportation and more walkable infrastructure.