I recently came across this fascinating comparison from the US Department of Energy’s FuelEconomy.gov, comparing the amount of energy a car takes from its input, and actually gets to the wheels between a gas powered car (16-25%), a hybrid (24-38%), and an electric car (60-65% + 17% for regenerative braking).
Being a huge nerd, I thought it would be interesting to actually see how this computes out on the fuel economy published for a gas powered car, vs an electric car.
| 1 |
| 3.6 MJ/h kW |
| 2 | ||
| 3 |
| 0.075 L/km |
| 4 |
| 0.25 h kW/mi |
| 5 | ||
| 6 |
| 47.5 MJ/kg |
| 7 |
| 0.76 kg/L |
| 8 |
| 35.8625 MJ/L |
| 9 | ||
| 10 |
| 2.69 MJ/km |
| 11 |
| 0.75 h kW/km |
| 12 | ||
| 13 |
| 160.9344 km |
| 14 |
| 0.16 h kW/km |
(Thanks Soulver for helping make a cool table, though for some reason it prefers the ‘h kW’ syntax of saying kWh ¯\_(ツ)_/¯)
So if we compare the two vehicles, on a kWh per/km basis (lines 11 and 14), the electric vehicle is 4.6 times as efficient as the gas powered vehicle, which is right in the ballpark of the estimates provided by FuelEconomy.gov.
I wonder if that means that electrification of the transport sector could bring something drastic like a 2-3x reduction in emissions from that sector? That’s pretty cool.
This also helps me clarify some computations I’ve seen done that argue that an electric car is still cleaner than a gas powered car, even if the electric car is powered by coal: Gas cars are just really darn inefficient; and I suspect that even though coal plants create a lot of carbon, they’re likely more efficient at extracting energy than a gas vehicle.