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Added more detail, but didn't account for the differences of GHG of each fuel yet.
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(Added more detail, but didn't account for the differences of GHG of each fuel yet.)
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If you charge an [[electric vehicles|electric car]] with electricity that was generated by [[fossil fuels]], is it '''as bad''' for the environment as driving a gas car?
If you charge an [[electric vehicles|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.'''
==Short answer==


Long answer:
'''Yes.'''


The carbon emissions are '''almost exactly the same''' for electricity generated by
* coal power plants
* ''simple'' natural gas power plants
For ''advanced'' natural gas power plants, which are more efficient, best-case carbon emissions are still more than '''half''' of what they'd be from driving a gas car.
==Long answer==


''For coal power plants:''
''For coal power plants:''
Line 49: Line 56:
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * coal_power_plant.efficiency
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * coal_power_plant.efficiency
|car.fuel_economy
|car.fuel_economy
|fuel_economy_if_coal
}}
}}


In other words, there's a ''very slight'' increase in overall fuel efficiency, but it's not much.
<!--SCRAP: In other words, there's a ''very slight'' increase in overall fuel efficiency, but it's not much.-->




''For natural gas power plants'':
''For natural gas power plants'':


Some have the same efficiency as coal power plants (33%). Results would be about the same as above. {{x|Although in theory, coal and natural gas have different GHG emissions per unit energy (which we didn't factor in, and maybe we should for best precision) - in practice, they're about the same, due to [[natural gas#fugitive emissions]]. Both are close enough to gasoline, for the purpose of the calculations on this page.}}
Some have the same efficiency as coal power plants (33%). Results would be about the same as above. {{x|Although in theory, coal and natural gas have different GHG emissions per unit energy{{x|which we didn't factor in, and maybe we should for best precision}} - in practice, they're about the same, due to [[natural gas#fugitive emissions]]. Both are close enough to gasoline, for the purpose of the calculations on this page.}}
 


''Other'' natural gas power plants (the more advanced "combined-cycle" type) are more efficient: up to 60%:
''Other'' natural gas power plants {{light|(the more advanced "combined-cycle" type)}} are more efficient: up to 60%:
{{dp
{{dp
|<nowiki>natural_gas_combined_cycle_power_plant.efficiency</nowiki>
|<nowiki>natural_gas_combined_cycle_power_plant.efficiency</nowiki>
Line 71: Line 80:
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * natural_gas_combined_cycle_power_plant.efficiency
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * natural_gas_combined_cycle_power_plant.efficiency
|car.fuel_economy
|car.fuel_economy
|fuel_economy_if_advanced_natural_gas
}}
<!--SCRAP: In this case (electric car + advanced natural gas power), we do in fact cut our emissions in half. But this doesn't apply to older, simpler natural gas power plants.-->
{{dp
|<nowiki>ev.battery</nowiki>
|<nowiki>65.2 kWh</nowiki>
|<nowiki>Energy capacity of the average electric vehicle battery</nowiki>
|<nowiki>Useable battery capacity of full electric vehicles</nowiki><br /><nowiki>
https://ev-database.org/cheatsheet/useable-battery-capacity-electric-car</nowiki><br /><nowiki>
</nowiki>
}}
{{dp
|<nowiki>li_ion.ghg_by_energy</nowiki>
|<nowiki>73 kg / kWh</nowiki>
|<nowiki>Greenhouse gas emissions (CO2eq) of producing a lithium-ion battery</nowiki>
|<nowiki>"by energy" here means "by the size of the battery, defined by how much energy can be stored".</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
What is the environmental impact of lithium batteries? - Changeit ...</nowiki><br /><nowiki>
changeit.app › blog › 2021-03-26-environmental-impact-of-lithium-batteries </nowiki>
}}
{{dp
|<nowiki>gasoline.ghg_by_energy</nowiki>
|<nowiki>71.30 kg / million btu</nowiki>
|<nowiki>CO2 emissions of burning gasoline</nowiki>
|<nowiki>https://www.eia.gov/environment/emissions/co2_vol_mass.php</nowiki>
}}
{{dp
|<nowiki>ev.lifespan</nowiki>
|<nowiki>8 years</nowiki>
|<nowiki>Expected lifespan of an electric vehicle</nowiki>
|<nowiki>Batteries usually are the component that wears out first.</nowiki>
}}
{{dp
|<nowiki>average_us_vehicle.mileage_by_time</nowiki>
|<nowiki>32 miles/day</nowiki>
|<nowiki>Distance driven by the average American vehicle</nowiki>
|<nowiki>Top Numbers Driving America's Gasoline Demand</nowiki><br /><nowiki>
https://www.api.org/news-policy-and-issues/blog/2022/05/26/top-numbers-driving-americas-gasoline-demand</nowiki>
}}
{{dp
|<nowiki>car.fuel_economy</nowiki>
|<nowiki>25.4 miles per gallon gasoline</nowiki>
|<nowiki>Gas mileage of an average American new car</nowiki>
|<nowiki>This datapoint is conformable with [electric_car.efficiency], because the calculator understands 'gallon gasoline' as an energy unit.</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Citation:</nowiki><br /><nowiki>
"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)."</nowiki><br /><nowiki>
- Fuel economy in automobiles - Wikipedia</nowiki>
}}
'''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, we're just going to count the emissions of making the batteries, and assume that making the rest of the car would take roughly the same emissions as making a gasoline-powered vehicle: {{x|Technically, the assumption is that the emissions ''divided by lifespan'' are about the same. Gasoline vehicles are more complex than batteryless EVs, but also have a longer lifespan.}}:
''Estimate for [[lithium-ion]] electric cars:''
{{calc
|ev.battery * li_ion.ghg_by_energy / ev.lifespan
|tonnes / year
|battery_ghg
}}
''Now compare for the gasoline a non-electric car would burn, on average:''
{{calc
|average_us_vehicle.mileage_by_time * gasoline.ghg_by_energy / car.fuel_economy
|tonnes / year
|gasoline_ghg
}}
''Now, for coal power plants charging EVs, same amount of driving:''
{{calc
|average_us_vehicle.mileage_by_time * gasoline.ghg_by_energy / fuel_economy_if_coal
|tonnes / year
|coal_ghg
|
|Imprecision note: {{x|This currently uses <tt>gasoline.ghg_by_energy</tt> when it should use <tt>coal.ghg_by_energy</tt>. The differences are minor though.}}
}}
''Now, for advanced natural gas power plants charging EVs, same amount of driving:''
{{calc
|average_us_vehicle.mileage_by_time * gasoline.ghg_by_energy / fuel_economy_if_advanced_natural_gas
|tonnes / year
|advanced_natural_gas_ghg
|
|Imprecision note: {{x|This currently uses <tt>gasoline.ghg_by_energy</tt> when it should use <tt>(natural_gas.ghg_by_energy + natural_gas.fugitive_ghg_by_energy)</tt>. The differences are minor though.}}
}}
''Add the battery emissions:''
{{calc
|battery_ghg + coal_ghg
|tonnes / year
|total_ghg_if_coal
}}
{{calc
|battery_ghg + advanced_natural_gas_ghg
|tonnes / year
|total_ghg_if_advanced_natural_gas
}}
'''''Now, for the final comparison:'''''
{{calc
|total_ghg_if_coal
|% gasoline_ghg
}}
{{calc
|total_ghg_if_advanced_natural_gas
|% gasoline_ghg
}}
}}


In this case (electric car + advanced natural gas power), we do in fact cut our emissions in half. But this doesn't apply to older, simpler natural gas power plants.
Thus, emissions are about the same for coal as gasoline-powered cars. Emissions are only a bit better for ''advanced'' natural gas power plants. Also this doesn't count the other environmental impacts {{light|(non-CO<sub>2</sub>)}} of mining lithium & cobalt.


<!-- TODO: redo this with more precision: coal.ghg_by_energy and natural_gas.ghg_by_energy? but then what about fugitive emissions? maybe make a datapoint "natural_gas.fugitive_ghg_by_energy" that factors it in -->


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.{{qn}}
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.
* Note: This varies by the ''type'' of batteries used.<!-- TODO: bring in data from other pages?: energy to manufacture batteries; minerals involved -->


When that's factored in, there's probably no benefit to having an electric car in the coal-power scenario, and only ''moderate'' benefit in the advanced-natural-gas-power scenario.
<!-- SCRAP: When that's factored in, there's probably no benefit to having an electric car in the coal-power scenario, and only ''moderate'' benefit in the advanced-natural-gas-power scenario. -->
<!--
<!--
  TALK: add scenario where fuel-cell vehicles are powered by hydrogen gas made from fossil fuels?
  TALK: add scenario where fuel-cell vehicles are powered by hydrogen gas made from fossil fuels?
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