First and foremost that 7% is a BS number I was being a bit facetious about, that only applies to…

True, it looks like coal fired plants are very old and inefficient, as you have stated, and it would be incorrect to omit that inefficiency from the calculation. That was an oversight on my part. Thank you for prompting me to look up the actual numbers.

Old coal plants appear to run at about 33% efficiency based on a fast search, which does not include transmission losses. I would guess, combined with those transmission losses, that a “tank” of coal-generated electricity would then approach or be in parity (or even exceed?) the inefficiencies I’ve previously cited for supplying a tank of petrol.

Based on these numbers, I’m very glad that coal plants appear to be only 39% of US energy production (as of 2013). Thankfully, other sources of energy generation can also be significantly more efficient. (Such as Combined Cycle Gas Turbines, which run at over 60% at full load. Source:

Many evaluations of EV efficiency appear to assume renewable energy generation rather than coal or even natural gas. This is only possible, though, in some geographical locations (or by personal investment into small scale solar, of course). So actual efficiency depends heavily on what area of the county the car is being driven in.

However, by your claim (yes, it was intentional hyperbole for rhetorical effect — I know), I’m sure a large number of Californians driving Teslas would be surprised to hear that they are driving “COAL FIRED VEHICLE[S] for all intents and purposes!”— “California’s total megawatt hours attributed to coal has dropped from 1 percent in 2007 to just two-tenths of one percent in 2015.” (Source:

I bring up this specific use-case to point out that ~40% US electricity generation by coal does not equal ~100% of energy powering US EVs being coal — which I take your comment about “[coal fired] for all intents and purposes” to imply — a bit of an rhetorical overreach, in my mind, even as a “not-intended-to-be-taken-literally” point-scoring attempt.

As the cost of new renewable energy sources continues to be driven down by innovation, as it has for the last decade, your justifiable concerns about the financial and environmental cost of new (as opposed to legacy) electricity generation will hopefully be allayed.

I grant you that for the EV industry to scale in a sustainable way, both supply side (mining) and disposal side (recycling) of batteries will need improvement and/or ethical sourcing to avoid just censure. Govt. regulation will possibly need to step in here if the industry doesn’t step up on its own.

Thank you for engaging with me on this fascinating topic.