BUSINESS
H2 WHOA The
FUEL-CELL CARS START TO ARRIVE After decades of development, sales of HYDROGEN-POWERED consumer vehicles will begin next year MELODY M. BOMGARDNER, C&EN WASHINGTON
CALIFORNIA AND JAPAN are places
where the future arrives a bit early. And so it goes with the hydrogen economy. They are where hydrogen fuel stations are being built and where consumers will soon have the opportunity to purchase fuel-cell cars to use for personal transportation. For a cool 7 million yen, or approximately $70,000, early adopters will be able to drive more than 400 miles on one fill-up of hydrogen and emit only water vapor. Toyota Motor will be first out of the gate with its FCV model, which is expected to go on sale in April 2015 in Japan and in the summer of 2015 in California. Hyundai, General Motors, Honda, and Daimler all plan to offer fuel-cell vehicles for consumers in the near future. Putting a fuel cell and hydrogen tank in a consumer sedan is the culmination of decades of research and development by automakers. GM powered its first hydrogen vehicle, called the Electrovan, in 1966 using fuel-cell technology borrowed from the space program. Toyota’s effort began
in 1992, the same year it started developing the Prius gas-electric hybrid. Serious consumer road testing began in 2007, when a small number of sports utility vehicles powered by fuel cells were introduced for lease. Back then, which is not so long ago, the SUVs cost about $1 million apiece. A lot has happened since. The cost of fuel cells has come down, vehicle range has gone up, and performance goals, such as the ability to start up in frigid weather, have been met. Future hydrogen-powered drivers can thank innovations in chemistry and materials science for some of the most critical improvements, particularly inside the fuel cell itself. Reaching the mass market still requires
TOYOTA MOTO R
Toyota FCV runs on hydrogen and emits only water vapor.
additional cost reductions of around 50%. And before fuel-cell cars can make a real impact on consumer transportation, infrastructure for hydrogen fuel stations must be built, and car buyers must switch to the technology in large numbers. “I can’t say that the technology will become popular until at least 2025,” predicts Toru Hatano, an analyst at the consulting firm IHS Automotive. “As long as we can use other fuels—whether it’s gasoline, diesel, ethanol, or natural gas—consumers will not choose fuel-cell vehicles.” Toyota and GM are taking different approaches to the adoption problem, while both firms actively work to make fuel cells less expensive. Toyota’s plan is focused on gaining consumer acceptance; it is even helping to finance the installment of hydrogen fuel stations. GM, for its part, has teamed up with Honda to make fuel-cell cars more cost-competitive. THE EARLY generation of fuel-cell ve-
hicles will compete with hybrid- and all-electric vehicles for the hearts and minds of low- or zero-emission car buyers. Although Toyota has had success with the Prius and other hybrid vehicles, it is now betting on a fuel-cell future, rather than an all-electric one. “Battery-electric vehicles are limited
“Over the last decade, improvements in fuel-cell technology have lapped battery technology three or four times.” CEN. ACS.ORG
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HOW HYDROGEN FUEL CELLS WORK 1 Pressurized H2 gas from the car’s hydrogen storage tank enters the anode. Oxygen from ambient air enters the cathode side of the fuel cell. The hydrogen travels in channels etched in the anode’s surface, which distribute the hydrogen over a platinum catalyst. 2 At the anode, the catalyst splits hydrogen into protons and electrons. At the cathode, the oxygen gas is forced through a catalyst, which forms two negatively charged oxygen ions.
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The negatively charged cathode causes protons to split off and move away from the anode through the proton exchange membrane (PEM). Electrons, now split from the hydrogen, form an electric circuit that powers the car and charges its battery.
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SHUTTERSTOCK/C&EN
When the protons meet the negatively charged oxygen atoms, the fuel cell produces water as a waste product.
in a lot of ways,” says Jana Hartline, environmental communications manager for Toyota Motor Sales U.S.A. The lithium-ion battery packs are too large and heavy to power efficient, convenient, and reliable vehicles. Future battery chemistries will make only an “incremental” difference, she argues. “Over the last decade, improvements in fuel-cell technology have lapped battery technology three or four times.” Toyota points out that the convenience factor tilts heavily in favor of fuel-cell vehicles. The driving range is greater than what’s provided by all-electric and even many gas-powered vehicles. And a fill-up of hydrogen takes only three minutes, compared with overnight for a full battery charge in an all-electric car. Since 2008, Toyota scientists and engineers have more than doubled the power density of the firm’s fuel cells. The smaller footprint means the automaker can fit a fuel cell under the seats of a regular-sized
car, rather than under the hood of a hulking SUV. More strikingly, the cost of the fuelcell system has been reduced by 95%. THE MAIN REASON for the cost breakthrough is a better catalyst that uses significantly less platinum. The catalyst enables a fuel cell to transform the energy in chemical bonds into electrical power. When hydrogen from a fuel tank flows to the anode side of the cell, it meets a platinum catalyst that splits it into two protons, leaving electrons that can be harnessed to both charge a vehicle battery and run an electric motor. Like Toyota, GM has been busily removing platinum from its catalysts. In 2007, GM’s test model, called Project Driveway, used 80 g of platinum in its stack of fuel cells. “My workhorse system now is using below 30 g,” says Charles E. Freese, executive director of GM’s global fuel-cell activities. In development, Freese adds, is CEN. ACS.ORG
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a stack that uses less than 10 g of the precious metal. The secret has been to use much more surface and much less platinum to get the same catalytic power, Freese explains. It requires depositing a thin layer of catalyst on a carbon support structure. To further increase the surface area, GM is working on techniques including hollow-shelled metal particles and special layering of the atomicscale shells. Alloys of platinum and cobalt are also being tested. Not all of the combinations of surface modification and catalyst work in reallife conditions, Freese acknowledges. The carbon support may oxidize, and the platinum can migrate and form clumps, which changes its catalytic properties. “These things don’t go right by accident,” Freese says. The goal: a catalyst that maintains its activity over at least a 10-year, 150,000-mile vehicle life span. Durability is also key to the performance
of another important part of the fuel cell, the proton exchange membrane. The PEM conducts protons—the result of splitting hydrogen—from the anode side of the fuel cell to the cathode side. DuPont has been making PEMs for fuel cells for more than 40 years. Its leading contender, called Nafion, is a sulfonated tetrafluoroethylene-based copolymer. THE MEMBRANE can shuttle protons only
when it has absorbed water, explains Randy Perry, a principal investigator at DuPont. The addition of water makes Nafion ionic—it contains both positive and negative ions. The negative ions are attached to the membrane, whereas the positive ions are mobile. “They come in one side, and other protons go out the other side,” Perry says. In contrast, electrons don’t move well through water, so they stay behind. One good way to make a fuel cell more powerful is to increase the number of protons that can move through the polymer membrane. And proton conductivity has improved dramatically since the late 1990s, thanks to experiment and design work
“In 20 to 40 years’ time, we might see the extinction of the combustion engine.” It may seem strange that automakers are doing so much of their own development work rather than outsourcing to suppliers such as Ballard Power Systems, a large fuelcell maker. Indeed, each major automaker will likely spend around $5 billion on fuelcell vehicle programs, estimates Cosmin Laslau, an analyst at Lux Research. Cars are much different from the stationary generators for which many commercial fuel cells were designed. “The fuelcell-making companies did not develop their products for automotive use but rather tried to adapt them for that use,” GM’s Freese explains. “But the requirements are very demanding; you can’t just take an offthe-shelf product and have it work without compromising the functionality of the vehicle.” Even purchasing raw materials is tricky, he adds. “You can get the very best of everything and get a very poor fuel cell.” Currently, Ballard does not manufacture
conducted under actual driving conditions, according to Perry. Matthias Gebert, product manager for fuel-cell membranes at chemical maker Solvay, says his firm likewise has made strides in maximizing the ion-exchange capability of its Aquivion fluoropolymer. Thinner structures have reduced raw material costs, he says, and composite blends with dedicated additives impart robustness. Further improvements are coming, Gebert adds, “but you will be surprised how the 2020 car will already be very much like what we are used to today.” Back at Toyota, another material win was to store onboard hydrogen in a smaller space. The company is weaving its own carbon fiber tanks that compress the gas to 70 megapascals. The resulting 20% increase in density means the FCV model coming out next year will have only two tanks versus its predecessor’s four.
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(1) a) Hartwig, J. et al. Angew. Chem. Int. Ed. 2011, 50, 3793; b) Hartwig, J. et al. Org. Lett. 2014, 16, 1744. (2) Zhang, X. et al. Angew. Chem. Int. Ed. 2014, 53, 1669. (3) Umemoto, T. et al. J. Am. Chem. Soc. 2010, 132, 18199. (4) Weng, Z. et al. Angew. Chem. Int. Ed. 2013, 52, 1548. (5) Shen, Q. et al. Angew. Chem. Int. Ed. 2014, 53, 9316.
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How To Fill Up, On Hydrogen Range anxiety. For many drivers of allthey will spend $26 million to install electric vehicles, this psychological con20 stations in Germany. California dition impinges upon the satisfaction currently has nine open stations, with that comes from spending big bucks to 49 in development, according to the decrease one’s carbon footprint. But California Fuel Cell Partnership. In May, eco-minded drivers who choose fuel-cell the California Energy Commission anvehicles don’t have to worry about being nounced $50 million in grants that are stranded with a dead battery. funding 28 stations. A major awardee, A hydrogen fuel-cell vehicle is a type FirstElement Fuel, also received loan of electric vehicle. Thanks to the ability backing from Toyota Motor. to carry around hydrogen, fuel-cell cars There’s no problem with supplies of can generate enough electricity to travel hydrogen to stock the stations. Indus400 miles or more without stopping for a fill-up. That’s a comforting margin compared with 66 to 84 miles for the electric Nissan Leaf. Another bonus: Filling up a tank of hydrogen takes about three minutes, rather than the hours required to recharge an electric-car battery. But finding a station that delivers hydrogen is much more NO WAITING Fuel-cell difficult than locating an trial gas firms such as Linde, vehicle drivers will be electrical outlet, at least Air Products & Chemicals, able to fill up at Linde’s for now. and Air Liquide stand ready hydrogen station in Hydrogen fuel stations to meet demand. But most Unterschleissheim, are beginning to pop up in of those fill-ups of hydrogen Germany. certain areas of California, will be made from fossil Japan, Germany, and the fuel—specifically natural gas U.K., totaling around three dozen today. via the steam reforming of methane. They are pricey to install, costing be“This is the number one concern that tween $1 million and $2 million apiece. we hear from many people: ‘It’s only And at the moment, they get little use; emission-free if hydrogen comes from fuel-cell cars on the road today number renewable sources,’ they say, and it’s a in the hundreds. But proponents of fuelfully valid point,” says Matthias Gebert, cell transportation acknowledge that product manager for fuel-cell memthe stations must come first. branes at chemical maker Solvay. Thanks to government grants, as well Experts envision a few routes to as partnerships of automakers, indusrenewable hydrogen production. For intrial gas firms, and hydrogen station stance, methane captured from organic development companies, many more waste can take the place of gas from unstations will be operational in 2015 and derground, Linde’s Beckman points out. beyond. “Governments have been very Another option is to electrolyze water supportive. There is a big driving force into hydrogen—with devices closely to convert to this technology and get related to fuel cells—using renewable infrastructure out there to support the but intermittent energy sources such as rollout of fuel-cell vehicles,” says solar or wind. Gebert sees this happenMichael Beckman, head of hydrogen ing within a decade or two. “The clean fueling at Linde North America. well-to-wheel energy chain will thus Last month, Daimler and Linde said become complete,” he says.
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LINDE
fuel cells for use in consumer automobiles. Instead, it lends its expertise to automakers via partnerships; Ballard has such an arrangement with Volkswagen, Laslau says. It’s not clear when or if carmakers will see a return on their fuel-cell investments. “In the long term, the question is: ‘Are we really going to go away from combustion engines for serious environmental reasons?’ ” Laslau says. “In 20 to 40 years’ time, we might see the extinction of the combustion engine. But that’s fuzzy.” In the near term, the new technology will do a great deal to help manufacturers meet fleetwide emissions reduction targets, particularly in California, which gives extra credit for long-range, zero-emission vehicles. Crafting fuel-cell vehicles that suit the average consumer may take a decade or more, and Toyota, at least, is okay with that. “We’ve always been a muchlonger-term-planning manufacturer,” Hartline says. “With the Prius, people told us we were insane, but 6 million units later, hybrids are now in every manufacturer’s lineup.” ◾
