Cars that plug in to recharge, whether all-electric or plug-in hybrid, are a very small proportion of total U.S. vehicle sales today.

And the same applies to their global sales, which are less than 1 percent of a total worldwide volume now headed toward 90 million vehicles a year.

So today, the idea that electric-car sales might one day equal those of vehicles with combustion engines that emit exhaust into our shared air might seem absurd.

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But their sales seem all but guaranteed to rise, given the growing urgency of reducing carbon emissions to address climate change.

Virtually every global automaker now has at least one plug-in car in development, if not several, and activity is even more frenetic in China.

So when, we wondered, can we start to envision parity between sales of battery-electric vehicles and those fitted with gasoline engines?

We put the question to our Twitter followers, though we restricted it to the U.S. market, since that's where a majority of our readers are.

And unlike many of our previous poll results, this one covered a wide range of responses—no one alternative clearly beat the others.

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Four out of 10 respondents said that gasoline and electric cars would reach a 50-50 balance in 2030, a more optimistic scenario than you'll find from most industry analysts.

But almost equal numbers of participants said it would happen in 2025 and 2050 (25 percent and 27 percent respectively), neatly bracketing the 40 percent who chose 2030.

2016 Chevrolet Volt

2016 Chevrolet Volt

And a mere 8 percent chose the most pessimistic option: "Never."

Which probably isn't surprising, given this site's topic and its regular coverage of all varieties of electric vehicles.

For global plug-in car production to rise from its current hundreds of thousands a year to levels of 40 million or 50 million, a lithium-ion cell fabrication and manufacturing infrastructure has to be built from scratch.

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The capacity of the necessary lithium-ion cells (or newer energy-storage technologies) required to produce even several million electric cars a year will be immense, dwarfing the current production of small-format consumer cells.

The battery gigafactory outside Reno, Nevada, that's now being outfitted by electric-car maker Tesla Motors and its battery partner Panasonic is intended for half a million cars a year.

So to get to 50 million, the equivalent of 100 gigafactories will be needed globally. Think about that.


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