Power to the Protons
The dream of a hydrogen economy is a long-standing one. Fuel cells have been around since 1839, when British physicist William Robert Grove built a device that could reverse electrolysis, which most of us remember from junior high chemistry as the process of splitting water molecules into their constituent hydrogen and oxygen atoms simply by sending a mild electric current through water.
In a fuel cell, hydrogen and oxygen are combined to produce water and electricity. The core component of most fuel cells today is a catalyst-coated electrolyte sandwiched between two conducting plates. Hydrogen enters one of the plates, and oxygen from the air enters the other; the hydrogen then pushes through the electrolyte to get at the oxygen. Along the way, the catalyst induces the hydrogen atoms to give up their lone electrons, which are blocked by the electrolyte, leaving a pool of abandoned electrons in the first plate while the hydrogen ions migrate through to the other plate. Hooking up a wire between the two plates results in an electric current, as the electrons stream through the wire to link back up with the hydrogen ions, at which point the reconstituted hydrogen atoms combine with oxygen atoms to create water. The current will continue as long as fresh hydrogen is ushered into the first plate. To achieve high power outputs, sets of plates can be stacked together.
Cheap oil and the economies of the mass-produced internal-combustion engine conspired for well over a century to keep fuel cells out of sight and mind. But in the 1970s, concerns about air pollution and the reliability of the oil supply inspired renewed interest in the technology. Because fuel cell processes scale up and down without loss in efficiency, product development today ranges all over the map. Motorola, for example, wants to put fuel cells on chips that could power cell phones that take fountain-pen-cartridge-like hydrogen refills (see “A Fuel Cell in Your Phone,” TR November 2001). Others seek to use them to run electric-power generating stations big enough to meet the needs of a small city. The federal government has been spending about $90 million a year on fuel cell research (though funding for all alternative-energy projects is expected to shrink under President Bush).
But the real attention in fuel cell research has been focused on cars. Faced with the ever present pressure to lower polluting emissions and the natural limitations of the internal-combustion engine, auto manufacturers have collectively poured over $2 billion into fuel cell research and development-both internally and in support of joint ventures such as DaimlerChrysler’s collaboration with fuel cell manufacturer Ballard Power Systems, of Burnaby, British Columbia (see “Fill ‘er Up with Hydrogen,” TR November/December 2000). But today’s very best fuel cells, though cleaner burning, still don’t come within honking distance of Detroit’s worst-performing engines when it comes to getting good power out of a lightweight, cheap, supportable package. And besides, the internal-combustion engine may be the most entrenched technology in existence-tooled and retooled over a century and a half to reach the limits of performance and reliability, manufactured in enormous quantities, and supported by a ubiquitous refueling and repair infrastructure. Since no one’s going to produce lots of fuel cells without first establishing a large market, and since the automobile industry lacks the immediate incentive to perfect the technology, the quest for automotive fuel cells is faced with a catch-22. “People get all excited about the hydrogen economy,” says Joel Swisher, a consultant with the Rocky Mountain Institute in Snowmass, CO. “But when it comes to figuring out how to get from here to there, the thinking grinds to a halt.”
Over the past two years, fuel cell manufacturers have become convinced they’ve seen a route around this dilemma. Their basic thinking now is that the best way to crack the automotive market is to first build the needed fuel cell production infrastructure and economies of scale by selling the devices in a smaller but less challenger-resistant market. That market, says a growing consensus of experts and businesses, is electrical-power generation: although fuel cells cost about 10 times as much to manufacture as a typical car engine, they are now only about twice as expensive as comparable fossil-fuel power generators. “The R&D and large-scale investment has been on the automobile side,” says Los Alamos’s Stroh. “But it’s probably true that the first products will be on the power generation side.”
Many players in the fuel cell manufacturing business have at least partly shifted their attention from the automobile arena to the power generation market. Among them: Ballard, now working to bring out units for residential and portable applications; H Power in Clifton, NJ, which is preparing a 4.5-kilowatt unit; and Plug Power in Latham, NY, a General Electric-backed company which will begin shipping the GE HomeGen 7000 this year. Even General Motors has announced plans to bring out a fuel-cell power-generation product.
One company that inarguably has a head start in this suddenly glamorous subindustry is International Fuel Cells of South Windsor, CT. Not only has the company long been developing fuel cells aimed at power generation applications, it has actually been selling them for nearly 40 years. Back in the 1960s, the company delivered the three fuel cells used in Apollo spacecraft to generate electricity, and later did the same for the space shuttles. While those fuel cells have never had any commercial application-they rely on costly gold-plated components, for one thing-International Fuel Cells leveraged its experience with them to design a unit called the PC25, a device that generates 200 kilowatts of power, enough to meet the needs of a medium-sized office building. Over the past six years the company has sold more than 220 PC25s in 17 countries to a variety of businesses, schools and government agencies that wanted to replace, supplement or back up electricity from local utilities.
The core component of the PC25 has the sandwichlike design found in most fuel cells. The outside of the sandwich is composed of two conducting plates riddled with channels for ushering gases in and out. In between the plates is an electrolyte efficient at conducting protons; the electrolyte is surrounded by a platinum-based catalyst.
The electricity production process in the PC25 begins when natural gas is piped through a standard gas utility connection into the unit’s fuel reformer, which is essentially a mini chemical plant that enlists a small series of heat-based processes to convert natural gas, methane or even gasoline into hydrogen, with carbon dioxide left over. After conversion, hydrogen gas is pulled through the channels of one of the plates and into contact with the catalyst-coated electrolyte, where the catalyst strips the electrons from the hydrogen atoms.
After the electrons reach the second plate and link back up with the protons, the reconstituted hydrogen atoms combine with oxygen atoms in the air to create water, helped along by the catalyst. Some of the water is absorbed by the electrolyte, which won’t work if it dries out; the rest of the water is channeled to a tank, where it can be drained off. Each sandwich, or cell, in the PC25 puts out less than a kilowatt of power; to achieve its full 200-kilowatt output, a PC25 uses a stack of 272 of these cells.
When employed as a utility-power backup, the PC25 typically remains in constant operation, churning out electrical power that’s directed into the utility’s power grid (for which the PC25’s owner normally receives credit); if the utility power fades or cuts out, an electrical switch redirects the PC25’s output from the grid to the local facility in a fraction of a second, keeping the facility flush with power.
Why would anyone want to switch from conventional electric-power sources to a fuel cell like the PC25? One might assume the greatest virtue of a fuel cell is that it eliminates the need for fossil fuel, currently the source of about two-thirds of U.S. electrical energy. Considering that hydrogen accounts for about two-thirds of all the atoms that constitute our planet, being able to harness it as a source of energy almost sounds too good to be true.
It is. The hitch is simple: hydrogen may be all around us, but it’s chemically locked up in water and other molecules. As it turns out, the only practical source of hydrogen available now is the same one that we’ve long relied on: hydrogen-rich hydrocarbons, which, practically speaking, means fossil fuels. To extract hydrogen, the fuel reformers themselves need to be powered.