When it comes to zero-emission vehicles, Toyota has placed its flag firmly on the side of hydrogen fuel cells.

The company is now reviewing requests from potential buyers and lessees of its 2016 Mirai fuel cell car, which is expected to hit California roads before the end of the year.

Meanwhile, in attack ads and multiple public comments by officials, the Japanese carmaker has consistently criticized battery-electric cars.

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Now, one executive explains why Toyota is so negative: He claims it's Toyota's long experience with high-voltage automotive batteries that makes it so skeptical of battery-powered vehicles.

Two decades of development and production experience with batteries for hybrid-electric vehicles has convinced Toyota that they pose a fundamental "physics problem," said Craig Scott--the carmaker's national alternative-fuel vehicle manager--in a recent interview with Forbes.

"Nobody makes more batteries than Toyota," Scott said. "We've been doing batteries longer than anyone in the automotive business."

2003 Toyota Prius

2003 Toyota Prius

Toyota wasn't the first manufacturer to use some form of electric propulsion in production cars, but it's likely built more cars with high-voltage batteries than any other single maker.

The company has sold more than 7 million hybrids since the first-generation Prius went on sale in Japan in 1997.

Note that the vast majority of electrified Toyota vehicles use nickel-metal hydride battery packs, not the lithium-ion chemistry found in production electric cars.

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Toyota alternative-fuel chief Scott said working with batteries for so long has convinced the carmaker that issues of energy density most likely won't be overcome.

He said that--for now--there are unassailable limits on how much electricity can be stored in a given volume, and how quickly a battery can charge.

"We don't see anything for the next 10 years," he said, noting that anything in the laboratory right now would take at least that long to transition to production.

2016 Lexus RX 450h

2016 Lexus RX 450h

That apparently isn't the case with fuel cells.

Scott reiterated that the 2016 Mirai already matches the range of many gasoline cars; it has been rated by the EPA at 312 miles of range, which is more than any electric car on sale today.

The only real challenge is finding ways to achieve lower costs for the fuel-cell stack and tanks, he suggested. No "physics problems" there.

MORE: Despite Quick Charging, Toyota Exec Says Electric Cars Won't Work For Long Ranges

While it reportedly believes batteries are adequate for short-range urban driving, Toyota does not think simply building larger battery packs--a la Tesla Motors--is a viable solution for mainstream models.

Scott did not directly address the challenges of planning, building, and paying for a pervasive hydrogen fueling infrastructure in the Forbes interview.

The Mirai will have a base price of $57,500; Toyota hopes to deliver 3,000 copies in the U.S. by the end of 2017.


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