The current conventional wisdom is that plug-in electric vehicles will be the clean, sleek cars of tomorrow. Think of Tesla's Model S or Chevrolet's Volt. These cars get most of the media attention, and policymakers tend to toss tax breaks their way.
Not all automakers, however, are persuaded that plug-ins are the only way to go. This month, Honda, Toyota and Hyundai all announced plans to produce hydrogen fuel-cell passenger vehicles in the next few years. These cars will run on compressed hydrogen — and emit only water vapor as exhaust.
For a long time, hydrogen fuel-cell vehicles were seen as a tantalizing technology to help reduce society's dependency on oil. In theory, fuel-cell vehicles could charge in minutes and go for hundreds of miles before refueling — overcoming the disadvantages of plug-in electric cars with their bulky batteries and limited ranges.
But the vehicles themselves were seen as forbiddingly expensive, and the challenges in setting up a hydrogen fueling infrastructure looked insurmountable. That explains why hydrogen lost its allure in the 2000s, particularly as batteries improved and electric vehicles became a reality. In 2009, the U.S. Department of Energy shifted its research and funding away from hydrogen and toward battery-driven electric cars.
Now the pendulum may be swinging back. Plug-in electric cars aren't selling quite as well as their advocates once hoped. And the cost of hydrogen fuel-cell vehicles seems to be dropping. Could hydrogen be in for a comeback? Or are the obstacles still too steep?
Toyota's fuel-cell plans
Toyota's emphasis on hydrogen is especially noteworthy. Sixteen years ago, the Japanese automaker was the first company to produce a commercially successful hybrid-electric car — the Prius, which features both a gasoline engine and an electric motor whose battery is charged by braking energy. That success led to a rising interest in electric cars.
Yet unlike many companies, Toyota isn't focused on all-electric vehicle as the logical next step. "The reason why Toyota doesn’t introduce any major [all-electric vehicles] is because we do not believe there is a market to accept it,” said Toyota Chairman Takeshi Uchiyamada during a speech in Washington D.C. back in September.
Uchiyamada argued that battery technology still needs a few major breakthroughs before all-electric vehicles can compete with hybrids or traditional gasoline-powered cars — the batteries are expensive, have limited range, and take hours to recharge fully. So, for now, Toyota will focus on improving its line of hybrids to meet rising fuel-economy standards in the United States.
But the company is also betting on hydrogen. Toyota is promising a mass-produced fuel-cell vehicle in Japan by 2015 and one in the United States by 2016. The price? Between $50,000 and $100,000. That lower end is comparable to the cost of Toyota's Lexus sedans, and it's cheap enough that hydrogen vehicles could possibly have mass appeal — particularly if gasoline prices ever start rising again.
Other automakers agree that fuel-cell vehicle costs are falling dramatically. "These things are now ready for prime time,” John Krafcik, Hyundai's North American CEO, recently told the Associated Press. But is that enough to edge out plug-ins?
Fuel cells vs. plug-in vehicles
Let's start with a rough breakdown of the two technologies: Plug-in electric vehicles are powered by batteries that are charged through outlets. Hydrogen fuel cells, by contrast, use a chemical process to separate out the electrons in molecules of hydrogen gas that, in turn, power the car's electric motor.
The main advantages of hydrogen fuel-cell vehicles: They can charge within minutes and have a longer range than plug-ins. Toyota estimates that its fuel-cell cars will travel 375 miles before refueling. That's a huge deal. Right now, some analysts think plug-in vehicles are being held back by the fact that they take awhile to charge and have limited range.
What's more, the hydrogen fuel-cell vehicles themselves can be pollution-free. Oxygen is pumped into the system, and water and heat come out.
So, what's the catch? For starters, there are very few hydrogen fueling stations around the country. And building out a network could prove difficult. One 2008 study by the National Academy of Sciences estimated that it could require $55 billion of public investment just to get two million hydrogen cars on U.S. roads by 2023.
To be sure, plug-in charging stations aren't ubiquitous, either. But that's changing fast. As of 2012, there were 13,392 electric-charging stations around the country, compared with just 58 hydrogen stations. Plus, drivers can charge their plug-in vehicles in their garages.
That's why Nissan chief executive Carlos Ghosn has questioned whether hydrogen cars will ever catch on. “Where is the infrastructure?" he asked at the Tokyo Motor Show on Nov. 20. "Who’s going to build it?”
There are also potential environmental drawbacks to fuel cells, as the hydrogen fueling infrastructure requires a large amount of energy: The hydrogen gas first has to be split off from water, then transported to fueling stations, then condensed at high pressures, and then converted back into electricity inside the car. That's a relatively inefficient process
In the near term, natural gas could be used to produce the hydrogen. If so, the National Renewable Energy Laboratory has estimated that fuel-cell cars could produce more greenhouse-gas emissions than hybrid vehicles when you consider the entire life-cycle. (Though other studies disagree.) By contrast, plug-in electric vehicles tend to be more climate-friendly than conventional vehicles in most parts of the United States.
Fuel cells might not be a truly 'green' technology until the world has a surplus of carbon-free energy to produce hydrogen — a prospect that's still some ways off.
Could the technologies co-exist?
Both vehicle technologies have their advocates and detractors. Elon Musk, the CEO of Tesla, has argued that there's "no way" fuel cell technology will ever prevail, citing cost and environmental concerns. Toyota's officials, however, argue that Tesla's success with electric vehicles is "a rare case" — and that the future lies elsewhere.
But it's also possible that a variety of technologies could find their own particular niches in the decades ahead. More efficient gas-powered cars and hybrids could dominate as a "bridge" to the future, as Toyota's Uchiyamada has predicted. Meanwhile, battery costs could tumble, making plug-in electric cars more viable for short commutes. And hydrogen vehicles could catch on for long-haul trips. Right now, however, it's still unclear how this battle will shake out.
-- Der Spiegel has longer interviews with Toyota's fuel-cell team.
-- This 2008 National Academies of Science report offers a great overview of the challenges facing hydrogen fuel-cell vehicles. Joe Romm, a longtime critic of hydrogen technology, offers up more considerations here.
-- As battery prices drop, will plug-in vehicles finally catch on?