The Fuel-Cell Solution: Promise or Prophecy?
Fuel-cell technology, an energy source invented over 150 years ago, may hold the key to low-polluting or nonpolluting energy independence for the United States, and it incidentally offers the real possibility of quiet, clean power on cruising boats.
Every manned U.S. spacecraft, from the Gemini program of the 1960s to the present-day shuttle program, has used fuel cells to provide electricity and, in some cases, fresh water. More recently, the automotive industry is showing growing interest in fuel-cell development and production. Research has moved beyond the theoretical, and fuel-cell-powered prototype vehicles and electric generators exist and are now being field-tested.
In 1998, Iceland announced a 10-year energy plan that called for all transportation vehicles, including its fishing fleet, to switch to hydrogen-powered fuel cells. And in the fall of 2001, DCH Technology, of Valencia, California, launched and tested an 18-foot water taxi that uses a fuel-cell generator and batteries to power its electric motor. This year, a fuel-cell-powered moderate-displacement sailboat is scheduled to make its debut.
|The ST-74 installed in HaveBlue X/V-1 weighs 128 pounds and delivers 74 pound-feet of torque. Solomon Technologies considers it a suitable replacement for engines in the 35- to 55-horsepower range.
According to the California company thats developing the boat, the 42-foot Catalina Mark II HaveBlue X/V-1 will be able to make, store, and use its own hydrogen fuel. The boats electric drive system, an ST-74 electric wheel made by Solomon Technologies (301-274-4479, www.solomontechnologies.com), currently runs on a bank of batteries so that testers can determine its exact power usage in a range of conditions. Employing two disc-shaped variable-speed DC motors, the drive is regenerative: The motor not only provides electric-powered propulsion; when the boat is sailing, it becomes a DC generator, using the freewheeling propeller as a turbine.
Once testing is complete, HaveBlue LLC, a developer of patent-pending marine power and propulsion technology, intends to tie the electric drive unit to a fuel-cell power plant that uses hydrogen for fuel. In effect, the fuel will come from the ocean. A custom Newport 400 watermaker made by Spectra (415-526-2780, www.spectrawatermakers.com) will provide fresh water, and the hydrogen will be extracted from this by means of electrolysis and stored on board.
By the summer of this year, HaveBlue intends to have the demonstrator boat fitted with a fully self-contained ultra-low- or zero-emission system that can produce and store its own fuel and can provide all the power needed for propulsion and onboard electricity. The company anticipates that the first production units of the system will be available to boat manufacturers in late 2004 or 2005.
The principle behind a fuel cell has remained unchanged since Welshman William Robert Grove invented what he called a "gaseous voltaic battery" in 1839. Combining hydrogen and oxygen to produce electricity and water, Groves "battery" required fuel, in the form of hydrogen, rather than recharging. A fuel cell, like a conventional battery, produces electricity as the result of an electrochemical reaction. Although it uses hydrogen fuel, no combustion occurs, and the electricity- producing component has no moving parts. Unlike a battery, instead of recharging, you simply add fuel to sustain the reaction.
Today, there are several different types of fuel cells: the molten-carbonate, the alkaline, the phosphoric, the solid-oxide, and the proton-exchange-membrane (PEM). Each of these uses a different electrolyte; different ones operate best at different temperatures. Some, such as the solid-oxide fuel cell, require an operating chamber as hot as 1,800 F to work efficiently. The proton-exchange membrane holds the most promise for providing electrical power and propulsion aboard cruising boats, thanks to its power density (the amount of current produced for the units size) and relatively low operating temperature, which is less than 210 F. HaveBlue intends to use this kind of fuel cell on its test boat.
Much like a conventional battery, the maximum output of an individual fuel cell is about 0.6 volts. To produce the required voltage and amperage, several cells are combined (similar to a conventional battery) to form what is called a stack. For instance, Ballard Power Systems Mark 900 fuel-cell stack is made up of 400 cells, producing somewhere in the region of 240 volts and 75 kilowatts.
When pure hydrogen is the fuel, fuel cells are virtually emission free, contain few moving parts, and release only heat and water while operating. Fuel cells are robust and can be quite compact; there are even fuel-cell-powered flashlights. Unlike a battery, the discharge from a fuel cell is flat and predictable until the fuel is completely used up. Once that happens, simply refuel and the unit is ready to deliver full power again. But therein lies the problem: There arent many hydrogen stations along the highways or waterways of the world.
One solution is to use hydrocarbon fuels. Fuel cells can operate on virtually any fuel that contains hydrogen, such as gasoline, propane, natural gas, methanol, and diesel. But these fuels must first be processed to extract the hydrogen. Most mobile fuel-cell prototypes rely on hydrogen from hydrocarbon fuel and incorporate a component that processes these fuels. Unfortunately, the orphan molecules of this process include carbon monoxide, carbon dioxide, and nitrous oxide—all undesirable "greenhouse" gases (although emitted in levels still lower than that of an internal-combustion engine). And fuel cells running on ordinary hydrocarbon fuels arent nearly as efficient as those running on pure hydrogen, which isnt a very energy-dense fuel to begin with. Compressed to 5,000 pounds per square inch, hydrogen has only 10 percent of the energy density of gasoline.
In the near term, the most likely fuels for mobile fuel cells (which are primarily of the PEM type) are reformed gasoline, propane, and methanol, all of which contain significant amounts of hydrogen. Sadly for cruising sailors, diesels complex molecular structure makes it especially difficult to extract the hydrogen, so future research efforts will likely focus on other readily available fuels. But these fuels present their own special problems.
Ordinary gasoline is comparatively high in sulfur, which chokes the PEMs catalyst, so it cant be used in fuel cells. It must first be scrubbed of sulfur and other additives that are beneficial to internal combustion engines but toxic to fuel cells. This renders existing fuel refining, storage, and distribution systems incompatible for use with fuel-cell-powered vehicles.
But hydrocarbon fuels arent the only option. One solution to the fuel issue involves storing hydrogen in the form of metal hydride in fuel cylinders. Another involves storing hydrogen in the form of sodium borohydride liquid, which is nonflammable and nontoxic. After being catalyzed, hydrogen is produced, along with sodium metaborate, which is essentially borax. Chrysler has fitted one of these borax-powered fuel cells into a minivan, which began testing last April.
Fuel Cells Afloat
The potential for fuel-cell use at sea is significant. Initially, fuel cells will probably find application within generators. Coleman Powermate, in cooperation with Ballard, recently introduced a 1-kilowatt fuel-cell generator, called the Coleman AirGen, for the commercial market. Its the size of a piece of carry-on luggage, weighs 40 pounds, and is fueled by metal-hydride fuel cylinders. On a cruising boat, such a generator would be somewhat less convenient than a diesel genset because youd need another source of fuel other than that used by your propulsion engine and because its simply less powerful than a conventional diesel generator. The smallest 4-kilowatt diesel genset is roughly twice the size of the 1-kilowatt Coleman AirGen, albeit heavier. However, I suspect that fuel cells will become smaller, more efficient, and less expensive.
Unless a safe, efficient, and inexpensive method of storing hydrogen is found (the borax or metal-hydride methods hold the most promise), then fuel cells for boats are dead in the water. Its unlikely that special fuels (methanol or reformable gasoline) will make their way to the waterfront anytime soon, and even if they did, many skippers of diesel-powered vessels would be reluctant to give up relatively safe diesel for more volatile methanol or gasoline.
Provided that the fuel-supply problem is solved, the development of a vessel powered entirely by a fuel cell seems promising. A centralized fueling station for fleets of cars or trucks would substantially mitigate the fuel-distribution problem, thus lowering the operating cost. (United Parcel Service is one firm exploring this option.) For boats, fuel stations are already comparatively centralized, so its possible that metal hydride, fuel-cell borax, or pure hydrogen could be made available at some of these locations, in addition to gas and diesel.
HaveBlues ambitious approach makes obsolete the need for new infrastructure, since the hydrogen fuel is produced on board the boat and stored, possibly in the form of metal hydride, in storage tanks. But if, or how soon, the system will become a practical option for cruising sailors will depend on a number of factors, not the least of which is economics.
One part of the energy equation thats sometimes glossed over by fuel-cell advocates is the power thats required to extract hydrogen. Just as electricity must be generated to recharge the batteries of an emission-free vehicle, so the fuel—hydrogen—must be manufactured for the cell. Fuel processing requires power, and the byproducts of this process arent always as benign as the emissions of a fuel-cell powered car or boat. To fill this power deficit, HaveBlue says its system will rely heavily on "clean " energy sources, including solar panels and wind generators.
When perfected, fuel-cell technology may someday enable cruisers to ply the waters of the world with energy to spare while producing no harmful emissions. And if the technology truly succeeds, it might well change the world. But for now, at least, fuel-cell technology isnt the magic bullet that will eliminate our dependency on fossil fuels and halt global warming. It can, however, contribute to both of these goals if its developed in conjunction with other technologies.
Steve DAntonio is the service manager at Zimmerman Marine in Cardinal, Virginia.