[Science Scope] Are Electric Vehicles Truly Eco-Friendly? ② The Real Battle Is Fought on the Grid, Not on the Road

Carbon Emissions Vary Depending on the Source of Electricity Used for Charging
How Electric SUVs, Hybrids, and Spent Batteries Change the Environmental Report Card

Editor's Note'Science Scope' is a special feature series that takes an in-depth look at specific scientific and technological phenomena, analyzing their significance and future implications.

The environmental report card for an electric vehicle charged in Seoul is not the same as that for the same vehicle charged in France. This is because the indirect carbon emissions produced during operation differ depending on whether the electricity used by the electric vehicle comes from coal and natural gas or from sources such as nuclear, solar, or wind power.

Where and how the battery is produced is also important. If a battery is manufactured using electricity that is high in carbon intensity, the vehicle shoulders a higher carbon burden even before it leaves the factory. Conversely, producing and charging the battery with low-carbon power significantly reduces the vehicle's life-cycle greenhouse gas emissions.

Workers are dismantling used electric vehicle batteries at the lithium-ion battery recycling facility of Cawleys, a UK-based waste and recycling specialist. Utilizing materials recovered from spent batteries in new batteries can reduce the environmental burden associated with raw material mining and refining. Provided by Cawleys

The eco-friendliness of electric vehicles does not end with replacing the power source of cars with electricity. Power plants and the grid, battery factories and vehicle size, driving patterns, and even spent battery recycling are all interconnected.

The Same Electric Car's Environmental Impact Varies by Power Source

Electric vehicles have no tailpipe, but the electricity for charging is generated in power plants. Even if an electric car produces no direct carbon dioxide emissions, the carbon released in producing the electricity is counted as the vehicle's operating emissions.

Coal power plants emit substantial greenhouse gases. Power generation using liquefied natural gas (LNG) still produces carbon emissions, though generally less than coal. Nuclear, solar, and wind power have some life-cycle emissions when accounting for facility manufacturing and construction, but their carbon intensity is much lower than for fossil fuel generation.

Sora Lee, Senior Research Fellow at the Circular Economy Research Division of the Korea Environment Institute, said, "Even the same electric car will emit more greenhouse gases if charged by coal-fired power than by nuclear or renewable energy." She added, "With Korea's relatively high fossil-fuel energy mix, electric vehicles are already advantageous at present, and their environmental benefit will structurally grow as coal use decreases and renewables expand."

This transformation is already being seen in Europe. According to an ICCT analysis for 2025, the life-cycle greenhouse gas emissions of electric vehicles based on the EU's power grid were 24% lower than in the 2021 analysis. The study identified grid decarbonization as the primary reason.

The difference in electricity sources is also stark in a full process analysis led by Yohan Gimbert, Senior Data Analyst at Transport & Environment (T&E). For example, an electric car assembled with batteries made in China and operated in coal-dependent Poland still produced 37% less life-cycle carbon dioxide than a gasoline vehicle. If the battery is manufactured and operated in Sweden, emissions drop by as much as 83%.

In Korea, too, the most crucial variable is electricity. Wonjae Choi, Professor at the Department of Human-Machine Bioengineering at Ewha Womans University, noted, "Above all, the emission coefficient of the power source has the biggest impact," and added, "Reducing the greenhouse gases produced during electricity generation is the most direct way to lower emissions from electric vehicles."

When to Charge: A Key Factor Even in the Same Country

Even when the same electric vehicle is operated in the same country, emissions can vary depending on when it is charged. This is because the composition of power sources supplying electricity fluctuates by time of day.

Jooha Lee, a researcher at Ewha Womans University, Jarung Kim, Director of the Future Vehicle Research Office at the Korea Transportation Safety Authority, Professor Choi, and colleagues published a 2024 study in the Journal of the Korean Hydrogen and New Energy Society titled "Analysis of Well-to-Wheel Greenhouse Gas Emissions from EVs According to Charging Time." The study examined how the changing power mix by time of day impacts EV greenhouse gas emissions by applying Korea's hourly power mix data from 2022 to calculate well-to-wheel emission changes.

According to the study, compared to an average scenario that doesn't consider the time-based power mix, an electric car's well-to-wheel greenhouse gas emissions can be up to 16% higher or 28% lower depending on the charging time. In other words, even the same electric car can have a different environmental report card depending on when it is charged.

This suggests that in the future, 'smart charging' could evolve from being merely a method for saving on electricity bills to a means of carbon reduction. For example, by encouraging charging during periods of abundant renewable energy generation and delaying charging during peak demand times.

Electric vehicles not only add new demand to the power grid but can also function as energy storage devices that allow for the control of charging times.

Electric SUV or Hybrid: Car Type and Size Also Matter

Another variable determining the eco-friendliness of an electric vehicle is its size.

Large electric sport utility vehicles (SUVs) require bigger batteries and more materials such as steel and aluminum compared to small electric cars. As a result, greenhouse gas emissions during production increase and more electricity is needed to move the heavier vehicle. Just because a car is labeled 'electric' does not mean its environmental record is the same.

IEA analysis quantifies this gap. Compared to midsize electric vehicles sold in 2023 with similar driving ranges, the average battery size for electric SUVs was 25% larger. Average electricity consumption for electric SUVs was also 20% higher than for other electric cars.

The resource savings from downsizing vehicles are substantial. According to the IEA, if all electric SUVs sold worldwide in 2023 had been replaced with midsize electric vehicles, battery usage could have been cut by about 60 GWh without significantly affecting driving range. This translates to an estimated 6,000 metric tons of lithium, 30,000 tons of nickel, 7,000 tons of cobalt, and more than 8,000 tons of manganese.

In other words, the bigger the electric car, the more batteries and resources are required.

The comparison between hybrid and electric vehicles is even more complex. Hybrid vehicles use both an internal combustion engine and an electric motor, which means they require smaller batteries than all-electric cars, resulting in a lower carbon footprint at the manufacturing stage. Their fuel consumption is lower than conventional gasoline vehicles due to regenerative braking and engine efficiency.

Analysis of domestic passenger cars by Professor Choi's research team shows that when including vehicle production and disposal, the total greenhouse gas emission gap between electric and hybrid cars becomes narrower. Internal combustion engine vehicles (ICEV) have the highest operating emissions, while battery electric vehicles (BEV) produce no direct emissions on the road but do emit carbon during electricity generation and vehicle/battery production.

Professor Choi said, "In Korea, the greenhouse gas emissions from electric vehicles are generally lower than those for hybrids," but added, "it's not a 100-to-0 difference as the public might imagine."

Electric vehicles can reduce emissions further as the power grid becomes decarbonized. Conversely, hybrids also have room for improvement as fuel efficiency increases or the use of low-carbon fuels expands.

Professor Choi added, "Comparisons between electric and hybrid cars always require comprehensive analysis of the fuels used, as well as the production, use, and disposal of vehicles," stressing the need for "objective evaluation based on full life cycle analysis that reflects reality."

According to the IEA, on a global average, a midsize electric car sold in 2023 had a life-cycle emission that was 40% lower than that of an equivalent hybrid. However, in regions such as India, where coal dependence is high and average annual driving distances are relatively short, the gap may shrink to under 10%.

Ultimately, the question of "electric or hybrid?" cannot be answered simply by the vehicle's name. Factors such as vehicle size, battery capacity, electricity mix, fuel efficiency, driving distance, and vehicle lifespan all need to be considered.

The Environmental Record Continues Even After Scrapping the Vehicle

What happens to the battery after its useful life also affects the vehicle's environmental report card. Recovering lithium, nickel, cobalt, and other minerals from spent batteries for use in new batteries reduces the energy consumption and carbon emissions associated with mining and refining those minerals.

The raw battery materials themselves are also influential. According to the IEA, processing key minerals accounts for about 55% of the life-cycle emissions of nickel-manganese-cobalt (NMC) batteries. For lithium iron phosphate (LFP) batteries, the battery manufacturing phase accounts for nearly 50% of total emissions. Increasing the proportion of recycled materials from used batteries is crucial.

LG Energy Solution is accelerating its battery recycling business by signing a contract with Li-Cycle, the largest battery recycling company in North America, through its joint venture with General Motors (GM), Ultium Cells. Photo by Yonhap News Agency provided by LG Energy Solution

However, recycling itself requires energy. Transporting and dismantling batteries, as well as separating and refining materials, generates carbon emissions, and the reduction achieved varies depending on the technology used.

Professor Choi explained, "The greenhouse gases emitted from recycling spent batteries can vary depending on the recycling technology. The end result of vehicle lightweighting also depends on the type of material employed."

Senior Research Fellow Lee identified grid decarbonization as the most critical factor in improving electric vehicles' environmental performance. "From a greenhouse gas perspective, decarbonizing the grid is fundamental and has the broadest impact," she said, adding: "For areas that automakers and battery producers can directly control, improvements in battery and material production processes, as well as the development of recycling and safety management systems for spent batteries, are realistic solutions."

Electric vehicles are not "perfectly eco-friendly cars" that emit zero carbon. They leave a carbon footprint during production, operation, and disposal. However, the potential to reduce this carbon is fundamentally different from that of internal combustion engine vehicles. Whereas emissions from internal combustion engines accumulate mainly at the tailpipe, electric cars have far greater potential for emissions reduction in battery factories, power plants, the electric grid, and recycling facilities. This is why the most significant contest in the electric vehicle era takes place outside the car itself, rather than on the road.

This content was produced with the assistance of AI translation services.