russ_watters said:
Cool map; too much hype and bad analysis with it though:
...
They're telling the story they want heard, not the story the data tells.
Yes. And all these studies, including the one from "The Union of Concerned Scientists" use the wrong number for electrical generation - they keep touting the "greening of the grid" in terms of average generation, but that is almost 100% irrelevant. When you use an EV versus a gasoline car, you are creating added
marginal demand on the electrical grid. That added
marginal demand demand is met with fossil fuel on most grids. So
an EV is running almost 100% on fossil fuel.
(More discussion here): energyathaas.wordpress.com/2012/04/17/marginal-vs-average-generation-the-case-of-the-electric-car/
In their earlier report, the Union of Concerned Scientists even acknowledge this, but then ignore it, and use averages instead (!) (see page 6):
https://www.ucsusa.org/sites/default/files/legacy/assets/documents/clean_vehicles/electric-car-global-warming-emissions-report.pdf
"the marginal generation mix for electric vehicles is needed for evaluating the implications of a large-scale EV market"
and then go on to say:
average generation mix is adequate for providing information to consumers regarding vehicle purchase and use
I fail to see the difference between large scale use and an individual EV. Either one will require added marginal generation. And regarding an individual EV, recall the above that every little bit only helps a little bit. So who cares?
This info from the NAS is enlightening:
http://www.pnas.org/content/111/52/18490
They provide the externalities cost of gasoline, hybrid, diesel and EV on various grids. Note that an EV on NG is better than a hybrid at the time of publication, but look at an EV on a coal grid. So it only takes a small % of coal generation to power EVs for the average externality damages to exceed those of a hybrid.
So the only time an EV is really going to be charged by renewables, is on those occasional nights were there is an actual excess of wind, and occasionally if we have an excess of solar on a grid. But we won't be able to regularly match intermittent excess supply to regular demand, therefore much of the energy to charge EVs will still be coming from fossil. And from what I've learned about grid operations, if EVs were regularly and predictably requiring NG turbines to kick in, the grid operators would keep the coal plants running at a bit higher level to reduce costs, especially on low wind nights.
For all their benefits, I just don't see where EVs are any "slam dunk" in terms of an improved environment, and may actually be worse overall than a modern hybrid. And hybrids keep improving, whereas EVs are near theoretical efficiencies - it's all about the power source .