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Home Fuel Cells
There is a lot of potential power behind the concept of home fuel cells -- enough, say proponents, to some day substantially reduce U.S. dependency on imported oil, reduce fossil-fuel pollutants and diminish dependency on centralized power stations.
Fuel cells use the chemical energy of hydrogen (the fuel) and oxygen from the air to generate power. This is accomplished without combustion and, under ideal conditions, without pollution. Pure water and useable heat are the only by-products of the chemical reaction.
This portable commercial generator is suitable for indoor use. Companies are using them to keep their computer systems opperating in the event of a power failure.
Some knowledgeable advocates predict that within the decade, fuel-cell technology could be competitive with the cost of power from the traditional electrical grid. These advocates usually make this claim for somewhat remote locations, where fuel costs are very high and it is difficult to hook up to the grid. Beyond that, the technology could usher in a dramatic shift from the large, centralized power generating platform that has been predominant in this country for over a century, to a situation of decentralized power generated at the homeowner level. Others involved in the industry are more cautious with their timetables, but they see fuel-cell technology looming large on the farther horizon.
Awareness of fuel-cell technology dates back to 1839, when Sir William Grove, considered the father of the fuel cell, developed a new kind of battery by reversing the already known process of electrolysis. He did not use the term "fuel cell.
That was first used 50 years later by chemists Ludwig Mond and Charles Langer, who were trying to use air and coal gas to generate electricity. Rather, Groves invention was called the gas voltaic battery and was the start of the evolving technology.
Nothing much happened to further the fuel-cell story until scientists working on NASAs Gemini space program in the 1950s recognized a fundamental problem with extant battery technology. They looked around for a product that had higher reliability and lower weight than the lead-acid batteries then in use. In 1959, Dr. Francis Thomas Bacon, an engineer working at Cambridge University in England, created a workable fuel cell based on his modifications of Mond and Langers 27-year-old version. He created the Bacon Cell, which was considered the first alkaline fuel cell.
From that research came the first commercial use of phosphoric-acid fuel cells. That fuel-cell technology has not been attractive for residential applications because it operates at 200Ã° C (392Ã° F), and the electrolyte -- phosphoric acid -- is highly corrosive.
However, a new technology has emerged within the last 10 years that uses proton exchange membrane fuel cells (PEM fuel cells or PEMFC). "Researchers and developers are very enthusiastic about PEM fuel cells because they operate at a fairly low temperature -- about 80 degrees Celsius (about 180Ã° F),
says Kent Whitfield, P.E., senior staff engineer, Underwriters Laboratories Inc. "That relatively low temperature is important because it allows the fuel cell to come up to operational efficiency very quickly, with the ability to vary output based on demand. PEM fuel cells are highly responsive to variations in the energy consumed by blenders, toasters, and other household energy-consuming devices,
he explains. "This capability has revitalized fuel-cell technology at the drawing board.
"A fuel cell takes in fuel -- which for residential use will likely be hydrogen that probably will come from natural gas or propane because there is such a large distribution network already in place -- which is pumped through the reformer,
says Whitfield, who notes that most likely there will be a device that permanently connects the fuel cell to a homes natural-gas line. (Hydrogen is the most abundant element on earth and could potentially provide an unlimited fuel supply. But it does not normally exist in a free state, available as fuel. Therefore, it has to be derived from where it resides, either in water or locked in hydrocarbons such as natural gas, gasoline, propane, methanol and ethanol.)
The reformer removes the hydrogen atoms from the gas with the by-product of carbon-dioxide gas. The hydrogen atoms are used to create electricity. The by-product of this reaction is usually water vapor and heat.
The catalyst is the key to separating the hydrogen atom into protons and electrons, and also to recombining those with oxygen to create water. Hydrogen atoms enter into one side of the fuel cell and hit the platinum plate. That action strips off the electron, leaving the hydrogen proton. Only the proton passes through the membrane. The electrons left behind build up an excess negative charge on the anode. The anode is wired to the cathode on the other side of the cell, completing a circuit.
"The electrons want to achieve charge neutrality, so they flow to the positive cathode side of the cell, creating a current,
Whitfield explains. "The protons that passed through the membrane to the cathode side recombine with oxygen and the arriving electrons to form water.
The fuel cell produces direct-current electricity, which by itself has limited utility. "What you really want in your house is 120-volt, 60-hertz, sine wave power,
he notes. To achieve that, there is typically another component, called the static inverter, that turns the direct current into utility-quality alternating current. A single fuel cell produces only limited voltage, so individual cells are stacked together and referred to as the "stack.
The possibilities of PEM fuel-cell technology have sparked a recent resurgence of interest. Several dozen companies around the world are actively involved in the development of complete residential fuel-cell systems. Within the industry, residential systems are called small stationary systems (in the range of 0.5 to 10 kw), as opposed to large stationary systems (which can produce electrical output of 10 kw and up) and also distinct from portable fuel-cell systems. Many of these companies hope to introduce products to the public within a few years. In the meantime, there are numerous pilot and demonstration products in the United States, Europe and Asia set up to work out kinks and help refine the technology.
When available commercially, the small, stationary systems will be suitable both as backup or supplemental power for homes connected to the grid or as primary power for homes that are off the grid by necessity or choice.
"I think early on, the fuel-cell industry had intended to go from R/D (research and development) and in the lab to the mass markets in one step,
says Scott Wilshire, director of marketing engagement at Plug Power Inc., a Latham, N.Y.-based fuel-cell manufacturer. "But it is not a one-step proposition. It is really a nested set of learning curves that we are going through.
Wilshire sees four stages in the development of stationary fuel-cell system technology: early adopters, niche markets, off-grid applications and mass residential markets.
At this time, the industry is selling primarily to early adopters, though, Wilshire notes, the niche market is starting to take off. "Early adopters do not buy the fuel cells because they make sense economically -- because, as yet, they dont. The units currently do not provide financial payback over time.
Early adopters of fuel-cell systems include government organizations, utilities, research labs and universities.
Niche buyers for small, stationary fuel-cell systems typically have a need for uninterrupted power and may not want the maintenance cost and attention associated with a backup generator or battery power. Interested parties include the telecom industry, wireless broadband companies and cable companies.
"Because a fuel-cell system has virtually no maintenance and is sure to work when needed, companies looking at life-cycle cost rather than first cost are investing in the units,
says Whitfield, of UL.
And while the system is still very costly, it has some measurable payback beyond the lack of maintenance requirements, Wilshire notes. "Unlike batteries, there are no disposal problems, and unlike many other power generating choices, fuel cells do not pollute the environment.
Off-grid applications are primarily centered on businesses and homeowners remote from a utility and unconnected to any grid. Fuel-cell systems can be alternatives to diesel generators or other (air or noise) polluting power sources that require maintenance. This market is in the early stages of development, with potential for growth among off-grid businesses (including remote telecom sites) and up to 2 million off-grid households that currently derive their electricity from other sources. A percentage of those homeowners could possibly justify the higher price point of fuel-cell electrical delivery because it is quiet and maintenance free. Products for the off-grid market are expected to appear in about two years.
Because of current pricing and lack of data on reliability, substantial growth in the residential off-grid market is still perhaps three or four years off, Wilshire suggests. To be competitive with other options, a home fuel-cell system that is parallel to the grid has to provide electricity at or below the cost from the utility. "The impetus for mass-market adoption of fuel-cell systems in grid-connected applications would have to be strictly economics,
A few commercial products are already available or are being actively developed, aimed at niche markets, including Plug Powers GenSys and GenCore, Ballard Power Systems AirGen, and IdaTechs FCS 1200.
Plug Power is already selling 5-kw systems to utilities for future residential use. "On New Yorks Long Island, where it is virtually impossible to site a new power plant, the Long Island Power Authority (a local utility) has 62 individual systems connected into the grid at multiple locations, including direct-grid, commercial and governmental applications. Residential systems will follow later this year. They are using the units as virtual small-scale power plants,
Wilshire says. "This learning from single-customer settings complements more than 50 additional systems installed by over 25 customers, all generating the experience needed to continue the progress necessary to systematically approach the marketplace.
Additionally, Plug Power is introducing its GenCore product, a 5-kw hydrogen-fueled system priced at $15,000 targeting backup applications, including support of critical electric grid infrastructure, telecommunication and broadband applications.
The Ballard AirGen was devised to act as a portable generator for indoor operation, to deliver backup electricity for industrial, commercial and home installations. Currently, it is being marketed to information technology shops and companies IT departments as replacement for battery uninterrupted power supplies in the event of a power outage. Users plug appliances or electronics directly into it. The system, which costs about $5,995, includes a built-in surge-suppression system to insulate expensive electronics from high-voltage jolts and brownouts. Systems to be installed for home use will be fueled by three easily replaceable hydrogen canisters (sold separately) that snap into place even while the system is operating, the company notes. One or two systems could easily fit under a workstation or desk.
IdaTech, a subsidiary of the energy and technology company IdaCorp Inc., recently installed a 3.6-kw propane-fueled fuel-cell system in the Cascade mountain range near Bend, Ore. The project, part of IdaTechs field-test plan for propane and natural-gas fuel-cell systems, will enable testing of various operational scenarios common to an off-grid telecom site. The relatively high placement, at a location 6,200 feet above sea level, will also facilitate diverse environmental testing. Data collected from the project will help prove the technology in real-world applications, which the company says will accelerate adoption by commercial customers. IdaTech is also preparing for the commercial introduction of a natural-gas/propane combined heat and power platform for residential and small commercial applications.
The most immediate impetus for developing small, stationary fuel-cell systems is for backup, uninterruptible and remote power for commercial applications, such as telecom companies and banks. Here the expense of purchasing the fuel-cell power units and the expense of buying fuel to operate the system is set off by the amount of money that can be saved by avoiding the costs associated with power breakdowns. At this time, hydrogen fuel cells last only about 10,000 hours. To be competitive as a primary source of power, they need to last about 40,000 hours.
If the fuel-cell system is expected to operate only during outages from the utilities, then the relatively short lifetime of a hydrogen fuel cell is less of a problem than it would be if a home needed continuous power every day.
"If anything is going to slow progress in the adoptions of fuel cells it is their current cost,
agrees Whitfield. "Probably the main thing we are going to see a lot of manufacturers working on is technology that, one way or another, will reduce that cost.
All Is Not (Yet) Perfect
Alas, when a reformer is necessary to extract hydrogen either from natural gas or from other fuel, carbon dioxide -- a prime greenhouse gas -- is produced as a by-product (even if to a lesser degree than is produced by traditional power generation). Therefore, reformers are considered a stopgap solution until there is a better way to extract hydrogen from a fuel locally or until there is a hydrogen infrastructure to provide the fuel directly.
Right now, forward thinkers are hoping that the United States will be able to form a dedicated hydrogen infrastructure to produce hydrogen in centralized locations from nuclear power, wind generators, or even from photobiological methods (e.g., hydrogen-producing algae), thus doing away with reformers and consequent carbon-dioxide pollution.
The main problem with hydrogen generation right now is the cost-effectiveness of implementation. There are also concerns about transporting and storing hydrogen, issues already being addressed by several groups in the midst of working out codes and standards that will help ensure safety all along the way.
When the technology is commercially available, whether or not to choose this green technology over solar panels or wind generation will likely depend upon cost, which technology provides less pollution, and whether any added value associated with fuel-cell power is worth any (reasonable) additional cost. n
William and Patti Feldman are a husband-and-wife freelance team based in New York.