Archive:000/Electric vehicles/Fossil fuel powered: Difference between revisions

From the change wiki
VisualWikitext
(Accounted for the different GHG of different fuels. I still plan to refactor the calculations so the steps are less awkward.)
(Simplified the calculations)
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==Long answer==
==Long answer==


''For coal power plants:''
The following calculations compare the average gasoline-powered vehicle with the average [[lithium-ion battery]]-based electric vehicle. Greenhouse gas emissions are in tonnes CO<sub>2</sub> equivalent (CO2eq):
 
<!-- TODO: add a popup box for assumptions:
* no jevons paradox
* battery is the main difference in production emissions (EV as compared to gas car) (amortized over lifespan)
-->
 
'''Usage emissions''' <!-- not technically a heading. we don't want mediawiki to generate a table of contents. -->
 
{{dp
{{dp
|<nowiki>electric_car.efficiency</nowiki>
|<nowiki>electric_car.fuel_economy_equivalent</nowiki>
|<nowiki>100 miles per 34.6 kWh</nowiki>
|<nowiki>100 miles per 34.6 kWh</nowiki>
|<nowiki>The "gas mileage" equivalent for an average electric car.</nowiki>
|<nowiki>The "gas mileage" equivalent for an average electric car.</nowiki>
Line 39: Line 47:
|<nowiki>coal_power_plant.efficiency</nowiki>
|<nowiki>coal_power_plant.efficiency</nowiki>
|<nowiki>33%</nowiki>
|<nowiki>33%</nowiki>
|<nowiki>How much of the coal's heat energy becomes electricity</nowiki>
|<nowiki>How much of the coal's combustion heat energy becomes electricity</nowiki>
|<nowiki>Transformative Power Systems | Department of Energy</nowiki><br /><nowiki>
|<nowiki>Transformative Power Systems | Department of Energy</nowiki><br /><nowiki>
https://www.energy.gov/fecm/transformative-power-systems</nowiki>
https://www.energy.gov/fecm/transformative-power-systems</nowiki>
}}
{{dp
|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.
}}
}}
{{dp
{{dp
Line 47: Line 61:
|<nowiki>25.4 miles per gallon gasoline</nowiki>
|<nowiki>25.4 miles per gallon gasoline</nowiki>
|<nowiki>Gas mileage of an average American new car</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>This datapoint is conformable with [electric_car.fuel_economy_equivalent], because the calculator understands 'gallon gasoline' as an energy unit.</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Citation:</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>
"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>
- Fuel economy in automobiles - Wikipedia</nowiki>
}}
{{calc
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * coal_power_plant.efficiency
|car.fuel_economy
|fuel_economy_if_coal
}}
<!--SCRAP: In other words, there's a ''very slight'' increase in overall fuel efficiency, but it's not much.-->
''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{{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 {{light|(the more advanced "combined-cycle" type)}} are more efficient: up to 60%:
{{dp
|<nowiki>natural_gas_combined_cycle_power_plant.efficiency</nowiki>
|<nowiki>60%</nowiki>
|<nowiki>How much of the natural gas's heat energy becomes electricity, in an advanced "combined cycle" power plant</nowiki>
|<nowiki>This is considered a "maximum" value - the best natural gas power plants achieve this.</nowiki><br /><nowiki>
Simpler/older natural gas plants (no combined cycle) have only an efficiency of 33%, same as [coal_power_plant.efficiency].</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Read more: https://energyeducation.ca/encyclopedia/Natural_gas_power_plant</nowiki>
}}
{{calc
|electric_car.efficiency * li_ion.charge_discharge_efficiency * (100% - power_grid.losses) * natural_gas_combined_cycle_power_plant.efficiency
|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
{{dp
Line 171: Line 135:
"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>
"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>
- Fuel economy in automobiles - Wikipedia</nowiki>
}}
{{dp
|<nowiki>natural_gas_combined_cycle_power_plant.efficiency</nowiki>
|<nowiki>60%</nowiki>
|<nowiki>How much of the natural gas's heat energy becomes electricity, in an advanced "combined cycle" power plant</nowiki>
|<nowiki>This is considered a "maximum" value - the best natural gas power plants achieve this.</nowiki><br /><nowiki>
Simpler/older natural gas plants (no combined cycle) have only an efficiency of 33%, same as [coal_power_plant.efficiency].</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Read more: https://energyeducation.ca/encyclopedia/Natural_gas_power_plant</nowiki>
}}
}}


''For a gasoline car {{light|(typical amount{{x|using US-based statistic for lack of other data}} of driving)}}:''
{{calc
|average_us_vehicle.mileage_by_time / car.fuel_economy * gasoline.ghg_by_energy
|tonnes/year
|usage_emissions_if_gasoline
}}


'''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 an EV charged by coal power plants {{light|(same amount of driving as above)}}:''
{{calc
|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
}}


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:''
''For an EV charged by natural gas power plants {{light|(same amount of driving)}}:''
{{calc
{{calc
|ev.battery * li_ion.ghg_by_energy / ev.lifespan
|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
|tonnes/year
|battery_ghg
|usage_emissions_if_ev_natural_gas
}}
}}


''Now compare for the gasoline a non-electric car would burn, on average:''
 
''For an EV charged by ''advanced'' {{light|(combined-cycle type)}} natural gas power plants {{light|(same amount of driving)}}:
{{calc
{{calc
|gasoline.ghg_by_energy * average_us_vehicle.mileage_by_time / car.fuel_economy
|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
|tonnes/year
|gasoline_ghg
|usage_emissions_if_ev_advanced_natural_gas
}}
}}


''Now, for coal power plants charging EVs, same amount of driving:''
{{calc
|coal.ghg_by_energy * average_us_vehicle.mileage_by_time / fuel_economy_if_coal
|tonnes / year
|coal_ghg
}}


''Now, for advanced natural gas power plants charging EVs, same amount of driving:''
'''Battery emissions''' <!-- not technically a heading. we don't want mediawiki to generate a table of contents. -->
{{calc
 
|(natural_gas.ghg_by_energy + natural_gas.fugitive_ghg_by_energy) * average_us_vehicle.mileage_by_time / fuel_economy_if_advanced_natural_gas
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.
|tonnes / year
 
|advanced_natural_gas_ghg
For simplicity sake, let's 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.}}:
 
{{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
''Add the battery emissions:''
|<nowiki>li_ion.ghg_by_energy</nowiki>
{{calc
|<nowiki>73 kg / kWh</nowiki>
|battery_ghg + coal_ghg
|<nowiki>Greenhouse gas emissions (CO2eq) of producing a lithium-ion battery</nowiki>
|tonnes / year
|<nowiki>"by energy" here means "by the size of the battery, defined by how much energy can be stored".</nowiki><br /><nowiki>
|total_ghg_if_coal
</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>
}}
}}
 
''For battery production:''
{{calc
{{calc
|battery_ghg + advanced_natural_gas_ghg
|ev.battery * li_ion.ghg_by_energy / ev.lifespan
|tonnes / year
|tonnes/year
|total_ghg_if_advanced_natural_gas
|battery_emissions
}}
}}


Line 223: Line 211:


'''''Now, for the final comparison:'''''
'''''Now, for the final comparison:'''''
{{calc
{{calc
|total_ghg_if_coal
|usage_emissions_if_ev_coal + battery_emissions
|% gasoline_ghg
|% usage_emissions_if_gasoline
}}
}}


{{calc
{{calc
|total_ghg_if_advanced_natural_gas
|usage_emissions_if_ev_natural_gas + battery_emissions
|% gasoline_ghg
|% usage_emissions_if_gasoline
}}
 
{{calc
|usage_emissions_if_ev_advanced_natural_gas + battery_emissions
|% usage_emissions_if_gasoline
}}
}}


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 {{light|(non-CO<sub>2</sub>)}} of mining lithium & cobalt.
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 {{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 -->


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.
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.


<!-- 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?

Revision as of 00:58, 4 April 2023

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 are about the same as gas cars, if the electricity is 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 about half of what they'd be from driving a gas car.

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
car.fuel_economy
25.4 miles per gallon gasoline
Gas mileage of an average American new car
This datapoint is conformable with [electric_car.efficiency], 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
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 amount(...)( using US-based statistic for lack of other data ) of driving): average_us_vehicle.mileage_by_time / car.fuel_economy * gasoline.ghg_by_energy tonnes/year usage_emissions_if_gasoline (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 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 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: (...)( 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. ):

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 (calculation loading)

usage_emissions_if_ev_natural_gas + battery_emissions % usage_emissions_if_gasoline (calculation loading)

usage_emissions_if_ev_advanced_natural_gas + battery_emissions % usage_emissions_if_gasoline (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

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