Re: A hypothetical question

First, to be clear, the conversion to oil isn't being motivated by "reducing pollution" and so it's a bit of a false flag argument on the part of us railfans. The conversion is being made because 1) liabilities around starting forest fires are bad for business and 2) the efficiencies, economies, and reliability of burning oil, which are good for business.

Now on to the question at hand. The Telsa Model 3 EV claims a power consumption of about 26kWh/100 miles, or 0.26kWh/mile. To charge your car requires electricity, possibly generated in a number of ways, transmitted and distributed to a charging station. I worked in substation and transmission design for a number of years, so I'm going to recall some rough numbers for estimation. Let's say:

- 97% efficiency in transmission (total line losses)
- 95% efficiency in transformation (x4: generation step-up, transmission-distribution, distribution-household, household-car)

So for the 0.26 kWh per mile driven, 0.26 / [0.97 * (4*0.95)] = 0.33 kWh must be generated. In the US 2019, 38% of electricity was generated using natural gas, 23% coal, and the remaining 39% was a mix of nuclear and renewables. Because of the way the grid works in the US, you can't trace your electrons back to one particular generator or source type. So for this exercise I'm going to assume that your car's electrons came from a gas generator. (This is a reasonable assumption, and perhaps smears out the differences in emissions between coal, nuclear, gas, and renewable).

Depending on the plant configuration, gas plants can achieve anywhere from 40%-60% thermal efficiency. Let's be conservative and choose 40%. Which, now making the conversion to heat rate (3412 Btu/kWh * 0.33kWh), gives us 1126 Btu required heat input....or about 1.1 cubic feet of gas per mile driven.

Natural gas produces around 117 lbs CO2 per 1000 cubic feet burned. So, per mile, the Tesla produces about (1.1/1000 * 117) = 0.13 lbs of CO2.

A train load of people is, what, 300 persons? At 2.5 persons per EV, that is 120 vehicles. Making the 600 mile round trip from Denver:

600 miles/car * 120 cars * 0.13 lbs CO2/mile = 9360 lbs CO2 = 4.7 tons CO2....less than the train ride.

Using Todd's numbers @ 240 cars gives 9.4 tons CO2....equal to the train ride.

Although this is just a SWAG with ballpark numbers, the efficiencies of electric vehicles charged through a grid network cannot be ignored.

All data from eia.gov.



Edited 1 time(s). Last edit at 11/30/2020 11:41AM by rainbowroute.