If you charge an electric car with electricity that was generated by fossil fuels, is it as bad for the environment as driving a gas car?
Short answer
Yes.
The carbon emissions, compared to a gasoline car, are approximately:
- 135% for coal power plants
- 89% for older natural gas power plants (more common)
- 56% for newer natural gas power plants (less common)
Long answer
The following calculations compare the average gasoline-powered vehicle with the average lithium-ion battery-based electric vehicle. Greenhouse gas emissions are in tonnes CO2 equivalent (CO2eq):
Usage emissions
electric_car.fuel_economy_equivalent
100 miles per 34.6 kWh
The "gas mileage" equivalent for an average electric car.
Average Electric Car kWh Per Mile [Results From 231 EVs]
ecocostsavings.com › average-electric-car-kwh-per-mile
li_ion.charge_discharge_efficiency
85%
When you charge a lithium-ion battery, this much of the energy can be recovered. The rest is lost as heat.
Range: 80 to 90 %
from wikipedia; haven't found original source yet
power_grid.losses
5%
Electricity lost in transmission & distribution
Frequently Asked Questions (FAQs) - U.S. Energy Information ... - EIA
www.eia.gov › tools › faqs › faq
Nov 4, 2021 · "The U.S. Energy Information Administration (EIA) estimates that electricity transmission and distribution (T&D) losses equaled about 5% of ..."
coal_power_plant.efficiency
33%
How much of the coal's combustion heat energy becomes electricity
Transformative Power Systems | Department of Energy
https://www.energy.gov/fecm/transformative-power-systems
natural_gas_power_plant.efficiency
33%
How much of the gas combustion heat becomes electricity
This stat is for simple (older tech) natural gas power plants. The efficiency is the same as for coal and nuclear power. The process is the same: Heat boils water, creates steam to drive a turbine.
car.fuel_economy
25.4 miles per gallon gasoline
Gas mileage of an average American new car
This datapoint is conformable with [electric_car.fuel_economy_equivalent], because the calculator understands 'gallon gasoline' as an energy unit.
Citation:
"The average fuel economy for new 2020 model year cars, light trucks and SUVs in the United States was 25.4 miles per US gallon (9.3 L/100 km)."
- Fuel economy in automobiles - Wikipedia
coal.ghg_by_energy
95.35 kg / million btu
CO2 emissions of burning coal
https://www.eia.gov/environment/emissions/co2_vol_mass.php
gasoline.ghg_by_energy
71.30 kg / million btu
CO2 emissions of burning gasoline
https://www.eia.gov/environment/emissions/co2_vol_mass.php
usa.natural_gas.fugitive_ghg
176.1 million tonnes / year
Greenhouse gas CO2eq of fugitive methane leaks from all natural gas infrastructure in the USA
Environmental Protection Agency (EPA)
Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014
https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2014
2016 Complete Report (PDF)
Using data from 2014
usa.natural_gas.energy
27.9 quadrillion btu / year
U.S. energy consumption from natural gas combustion only
Environmental Protection Agency (EPA)
Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014
https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2014
2016 Complete Report (PDF)
Datapoint was found on page 115, from pie chart and line graph, using data from 2014
natural_gas.fugitive_ghg_by_energy
usa.natural_gas.fugitive_ghg / usa.natural_gas.energy
Fugitive emissions (CO2eq) of natural gas, per unit energy
Average based on US datapoints.
natural_gas.ghg_by_energy
53.07 kg / million btu
CO2 emissions of burning natural gas
Does not include the fugitive methane emissions from unburned fuel. Those vary by how the gas is burned.
https://www.eia.gov/environment/emissions/co2_vol_mass.php
ev.lifespan
8 years
Expected lifespan of an electric vehicle
Batteries usually are the component that wears out first.
average_us_vehicle.mileage_by_time
32 miles/day
Distance driven by the average American vehicle
Top Numbers Driving America's Gasoline Demand
https://www.api.org/news-policy-and-issues/blog/2022/05/26/top-numbers-driving-americas-gasoline-demand
natural_gas_combined_cycle_power_plant.efficiency
60%
How much of the natural gas's heat energy becomes electricity, in an advanced "combined cycle" power plant
This is considered a "maximum" value - the best natural gas power plants achieve this.
Simpler/older natural gas plants (no combined cycle) have only an efficiency of 33%, same as [coal_power_plant.efficiency].
Read more: https://energyeducation.ca/encyclopedia/Natural_gas_power_plant
For a gasoline car (typical usage):
average_us_vehicle.mileage_by_time / car.fuel_economy * gasoline.ghg_by_energy
tonnes/year
usage_emissions_if_gasoline_car
(calculation loading)
For an EV charged by coal power plants (same amount of driving as above):
average_us_vehicle.mileage_by_time / electric_car.fuel_economy_equivalent * coal.ghg_by_energy / coal_power_plant.efficiency / (100% - power_grid.losses) / li_ion.charge_discharge_efficiency
tonnes/year
usage_emissions_if_EV_coal
(calculation loading)
For an EV charged by natural gas power plants (same amount of driving):
average_us_vehicle.mileage_by_time / electric_car.fuel_economy_equivalent * (natural_gas.ghg_by_energy + natural_gas.fugitive_ghg_by_energy) / natural_gas_power_plant.efficiency / (100% - power_grid.losses) / li_ion.charge_discharge_efficiency
tonnes/year
usage_emissions_if_EV_natural_gas
(calculation loading)
For an EV charged by advanced (combined-cycle type) natural gas power plants (same amount of driving):
average_us_vehicle.mileage_by_time / electric_car.fuel_economy_equivalent * (natural_gas.ghg_by_energy + natural_gas.fugitive_ghg_by_energy) / natural_gas_combined_cycle_power_plant.efficiency / (100% - power_grid.losses) / li_ion.charge_discharge_efficiency
tonnes/year
usage_emissions_if_EV_advanced_natural_gas
(calculation loading)
Battery production emissions
So far, we still haven't counted the environmental impact of making an electric car, which is significantly more than for a gasoline-powered car.
For simplicity sake, let's assume that batteries account for the entire difference between electric cars and gasoline cars, in terms of GHG emissions of production divided by vehicle lifespan. (...)( A gasoline vehicle is a bit more complex than a batteryless EV, but the former also has a longer lifespan. )
ev.battery
65.2 kWh
Energy capacity of the average electric vehicle battery
Useable battery capacity of full electric vehicles
https://ev-database.org/cheatsheet/useable-battery-capacity-electric-car
li_ion.ghg_by_energy
73 kg / kWh
Greenhouse gas emissions (CO2eq) of producing a lithium-ion battery
"by energy" here means "by the size of the battery, defined by how much energy can be stored".
What is the environmental impact of lithium batteries? - Changeit ...
changeit.app › blog › 2021-03-26-environmental-impact-of-lithium-batteries
For battery production:
ev.battery * li_ion.ghg_by_energy / ev.lifespan
tonnes/year
battery_emissions
(calculation loading)
Now, for the final comparison:
usage_emissions_if_EV_coal + battery_emissions
% usage_emissions_if_gasoline_car
(calculation loading)
usage_emissions_if_EV_natural_gas + battery_emissions
% usage_emissions_if_gasoline_car
(calculation loading)
usage_emissions_if_EV_advanced_natural_gas + battery_emissions
% usage_emissions_if_gasoline_car
(calculation loading)
Thus, with coal power, emissions are worse than driving a gasoline-powered car. But for advanced natural gas power plants, emissions are about half. In either case, this doesn't count the other environmental impacts (non-CO2) of mining lithium & cobalt.
Maybe there would be a good case for fossil-fuel-electricity-powered vehicles if carbon capture and storage could be fully & safely applied to the power plants.
See also