Toyota: Mirai Hydrogen Fuel Cell Sedan Has Smaller Carbon Footprint Than an EV. Math Disagrees

Japanese automaker Toyota hasn’t had all that much luck lately when it comes to informational films and advertising, getting itself in hot water more times than we care to remember for portraying plug-in vehicles as slow, boring and unsuitable for everyday life.

Out of the frying pan: Toyota claims its FCVs have a lower carbon-footprint than EVs.

Out of the frying pan: Toyota claims its FCVs have a lower carbon-footprint than EVs.

There was the anti-EV ad from its luxury arm Lexus, then the not-so-well received Choices ad for its Prius plug-in hybrid. And who can forget the Lexus Dadchelor short which we called the REX-Swap Scandal: an ad so controversial and badly-executed that Lexus has pulled it from YouTube.

But now Toyota has gone one step further, claiming in an infomercial for its Toyota Mirai fuel cell sedan that the carbon footprint of hydrogen fuel cell vehicles smaller than that of a purely electric car.

As our friends over at Autobloggreen detail, that’s a pretty big claim, and one which the majority of the automotive industry is struggling to believe.

In the video above, a Toyota narrator details the company’s quest for a perfect environmentally-friendly vehicle, starting with the Toyota Prius hybrid and moving through the Plug-in Prius hybrid and all-electric cars like the Scion EV and RAV4 EV to the birth of the Toyota Mirai.

Just before the Mirai is introduced, the narrator utters the controversial line, referencing Toyota’s work with electric and plug-in vehicles and the simultaneous work it was carrying out on hydrogen fuel cell technology.

“Never satisfied though, Toyota engineers were simultaneously working on a brand new technology that met all the driver’s needs with an even smaller carbon footprint, one that took its lead from nature itself.”

It’s a claim which sounds great in an inspirational film designed to engage the audience and excite them about Toyota’s chosen fuel of the future. But it has one fatal flaw.

Toyota says it wasn't comparing FCV carbon footprints to electrics, but that's not what it sounded like.

Toyota says it wasn’t comparing FCV carbon footprints to electrics, but that’s not what it sounded like.

The math just doesn’t work out.

Transport Evolved regulars Paul Scott and Chelsea Sexton — who are both known for their tenacity and advocacy of electric vehicles — are both unconvinced.

“Toyota claims the FCV has a smaller carbon footprint than their EV, but every paper I’ve read indicates the FCV uses 3-4 times as much energy to travel a given distance as an EV,” says Scott. “If they are making this claim, let’s call them out to prove it. Show us the math!”

Sexton gave a similar response, telling Autobloggreen that “assuming appropriate comparisons in energy feedstock, basic science doesn’t support the notion that the footprint of an FCV is smaller than that of an EV.”

And we’d have to agree. From our own research, it takes nine litres of water and 56 kilowatt-hours of electricity to make one kilogram of hydrogen. From that, you can travel about 60 miles on average in any of the hydrogen fuel cell cars being made today.  As ThinkProgress details, only about 25 percent of the original energy used to create hydrogen through electrolysis ends up being used to power the vehicle: the rest is lost in the process of hydrolysis, the pumping and storage of the gas, and the vehicle’s fuel cell itself.

Whichever way you cut it, hydrogen fuel cells use more energy than battery electrics.

Whichever way you cut it, hydrogen fuel cells use more energy than battery electrics.

Of course, just like electric cars, the true carbon footprint of a hydrogen fuel cell vehicle depends on the type of energy used to create it. And as Sexton points out, it’s not unusual for fans of hydrogen fuel cell vehicles to compare solar-powered electrolysis hydrogen generation with dirty coal-fired power plants.

The result? The figures get skewed and the headlines twisted, prompting us to remind readers that it sometimes takes a bit of scientific paper study to find the real results.

For its part in this latest battle, Toyota says it does not directly compare electric cars to fuel cell vehicles. Instead, it claims, the informational video above merely highlights its progress over the last twenty years in terms of fuel-efficient technologies — meaning that fuel cell vehicles have a lower carbon footprint than traditional gasoline-powered vehicles or hybrids.

“BEVs and FCs have a very similar carbon footprint, dependent on the fuel source,” said Toyota spokeswoman Jana Hartline. We note however, that she didn’t specify which fuel sources she was referring to.

It all depends on the energy...

It all depends on the energy source…

Taken at face value, Toyota’s claim is a little vague. And to give it a little credit, if we only consider the energy used to run the vehicle rather than the energy used to make them, a hydrogen fuel cell car powered and refuelled from a solar-powered hydrolysis station (where any power transfer was powered by solar energy) and an electric car powered by power form a photovoltaic array nearby would have equally low emissions.

But in most situations, hydrogen has to be stored, pumped and transported, a process which uses energy and — if we assume the conventional fossil-fuelled tanker method — adds its own carbon footprint to the mix.

Even then however, there’s one inescapable fact of physics that’s hard to explain away: every time energy is moved or converted, there are losses. And that means kilowatt-hour for kilowatt-hour, hydrogen fuel cell vehicles are less energy efficient than their plug-in counterparts.

That’s a tough thing to try and explain away.

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