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

Revision as of 07:42, 31 December 2022

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.

Long answer:

For coal power plants:

electric_car.efficiency

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 heat energy becomes electricity

Transformative Power Systems | Department of Energy
https://www.energy.gov/fecm/transformative-power-systems

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

car.fuel_economy (calculation loading)

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%). Others (the more advanced "combined-cycle" type) are more efficient: up to 60%:

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

car.fuel_economy (calculation loading)

In this case (electric car + advanced natural gas power), we do in fact cut our emissions in half.

A note on precision: (...)( 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). But 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 above. )

But 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.^{[QUANTIFICATION needed]}

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. You can confirm or deny this hypothesis by adding more data to this page.

@@ Line 1: / Line 1: @@
-If [[electric vehicles]] are powered with electricity that was generated by [[fossil fuels]], is it worse for the environment than just 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.'''
+Long answer:
+''For coal power plants:''
 {{dp
 |<nowiki>electric_car.efficiency</nowiki>
@@ Line 44: / Line 50: @@
 |car.fuel_economy
 }}
+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%). Others (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
+}}
+In this case (electric car + advanced natural gas power), we do in fact cut our emissions in half.
+<small>A note on precision: {{x|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). But 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 above.}}</small>
+But 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}}
+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.
+You can confirm or deny this hypothesis by adding more data to this page.
+==See also==
+* [[Public transit]]
+* [[Walkability]]