Articles

RSS

By Cathy Swirbul

Dozens of companies worldwide—from Ford Motor Company to newly formed Avista Laboratories of Spokane, WA—are banking on the marketability of fuel cells, technology still in its infancy. A fuel cell is a device that chemically produces electricity that could power vehicles and portable devices, such as cellular phones and wearable computers, and provide electricity and heat for homes and other small buildings.

Fuel cells are an attractive power source because they have:

• high-energy conversion efficiency;
• modular design;
• very low chemical and accoustical pollution;
• fuel flexibility;
• cogeneration capability; and
• rapid load response.

Fuel cell developers promote the device as a power source for vehicles that will reduce urban air pollution and decrease oil imports. The U.S. Department of Energy projects that if 10% of automobiles nationwide were powered by fuel cells, regulated air pollutants would be cut by one million tons per year and 60 million tons of the greenhouse gas carbon dioxide would be eliminated. DOE estimates that the same number of fuel cell-powered cars would cut oil imports by 13%.

For the residential market, developers tout the fuel cell as an economical, emissions-free and reliable source of electricity.

Despite the market potential of fuel cells, developers face several obstacles to commercialization. Most of their current research and development efforts are focused on overcoming these hurdles and getting their products to the market within the next two or three years.

Fuel Cell Primer

A fuel cell consists of an electrolyte sandwiched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. A fuel cell system , which includes a fuel reformer, can use the hydrogen from any hydrocarbon fuel, from natural gas to methanol. Since the fuel cell relies on chemistry rather than combustion, emissions for this type of system are much smaller than emissions from the cleanest fuel combustion processes.

A fuel cell typically is comprised of three sections—a fuel processor, a power section (fuel cell stack) and a power conditioner. In the fuel processor, a fuel such as natural gas is reformed to boost the hydrogen concentration. The hydrogen-rich fuel and oxygen (air) then feeds into the power section to produce DC electricity and reusable heat. The power section includes a fuel cell stack, which is a series of electrode plates interconnected to produce a set quantity of electrical power. The output DC electricity is then converted to AC electricity in the power conditioning section where it also reduces voltage spikes and harmonic distortions.

There are four primary fuel cell types based on the electrolyte used:

• Phosphoric acid fuel cells are the most commercially developed. These cells were chosen for development more than 20 years ago because of their relative tolerance for reformed hydrocarbon fuels. These cells generate electricity at 40% efficiency and at 85% if the steam produced is used for cogeneration. In comparison, the most efficient internal combustion engine operates at 30% efficiency;

• Proton exchange membrane (or solid polymer) fuel cells have high power density and can vary their output quickly to meet shifts in power demand. The cell's hardware incorporates a plastic membrane separator that supports two laminated electrode layers. These cells' low operating temperature makes them suitable for applications where quick startup is required, such as in automobiles. Recent advances in performance and design offer the possibility of lower cost than other fuel cell types;

• Solid oxide fuel cells use a hard ceramic material instead of a liquid electrolyte, which reduces corrosion problems. To achieve adequate ionic conductivity in such a ceramic, the system must operate at about 1830°F (1000°C). This high temperature allows the cell to convert natural gas into hydrogen internally, preventing the need for a separate conversion unit and thus, reducing the cell's production cost and size;

• Alkaline fuel cells, which use alkaline potassium hydroxide as the electrolyte, can achieve operating efficiencies of 70%. The National Aeronautics and Space Administration (NASA) has used these cells on the GEMINI, Apollo and Shuttle space vehicles; and

• Molten carbonate fuel cells evolved from research in the 1960s aimed at producing a fuel cell that would operate directly on coal. While direct operation on coal seems less likely today, operation on coal-derived fuel gases or natural gas is viable. These alternatives are still in the testing stage.

For more information on fuel cell types, go to www.fuelcells.org or www.dodfuelcell.com.

Commercialization Obstacles and Solutions

The greatest barrier to commercialization of fuel cells is the high production cost. Fuel cell technology is young and not enough cells are produced to allow economies of scale. In addition, hydrogen is not readily available, and so more accessible fuels, such as natural gas, must be converted into hydrogen and carbon dioxide. This adds considerably to the fuel cell's cost. Currently, fuel cell developers are testing a variety of systems to reduce production costs.

For the residential power market, developers must reduce the fuel cell's operation/maintenance costs and the price per kilowatt in order to compete with combustion engines, according to Dan Rastler, area manager for distributed resources at EPRIsolutions. EPRIsolutions, a subsidiary of the Electric Power Research Institute (EPRI), published its 1999 assessment of the fuel cell industry in its report Technology Assessment of Residential Power Systems for Distributed Power Applications (TR-113897). Once these obstacles are overcome, fuel cells could be widely used in rural service areas and even residential mass markets for distributed generation, according to Rastler. Distributed generation refers to power that is produced on site where it is used.

Since 1993, the federal government has provided substantial funding for research and development because fuel cells provide efficient energy, while decreasing national dependence on oil imports and reducing urban air pollution. The U.S. Department of Defense coordinates the fuel cell funding provided by federal agencies, including the U.S. Department of Energy, the National Aeronautics and Space Administration and the Environmental Protection Agency (EPA). According to the 1998 DOD Report to Congressional Defense Committees, this funding has helped decrease the cost of phosphoric acid fuel cells, abated numerous air-emission contaminants and nurtured the future economic viability of fuel cell technology. Federal agencies continue to earmark substantial funds for fuel cell research. For fiscal year 2001, DOE alone has slated more than $100 million for fuel cell-related programs in its budget request.

Where the Fuel-Cell Industry Stands, Where it is Headed

Despite the challenges remaining to wide-spread commercialization of fuel cells, numerous developers are making great advances in research and development and a few have products already on the market. Other developers plan to introduce their products to the market within the next two to three years.

Phosphoric Acid Fuel Cell. This fuel cell already has achieved commercial success as a result of government grants for environmentally sensitive applications. ONSI Corporation, a subsidiary of International Fuel Cells Corporation, based in South Windsor, Conn., is the primary developer. Government grants have reduced the cost of the company's fuel cells, making the product competitive. Currently, this cell is used to provide power and heat at hospitals, nursing homes, hotels, schools and utility power plants. Many industry analysts predict molten carbonate and solid oxide fuel cells eventually will overshadow phosphoric acid fuel cells in the marketplace. The first two cells run at high temperatures and therefore are able to convert natural gas to hydrogen internally. The phosphoric acid fuel cell runs at a lower temperature and, therefore, an extra unit must be added to the cell for conversion. This adds considerable cost and size to the cell.

Proton Exchange Membrane Fuel Cell. The U.S. Department of Energy has deemed this cell the primary candidate to power light-duty vehicles, and provide power to buildings and small applications such as in video cameras. This cell operates at a low temperature. Therefore, the electrodes require a platinum catalyst to promote the chemical reactions. Research done by the UK's Johnson Matthey and other groups has led to the production of high-performance electrodes using very low platinum loadings. Currently, research is directed at lowering the cost of the electrolyte, also known as a "proton exchange membrane."

The Canadian company Ballard Power Systems and Plug Power, based in Latham, NY, are two of the leading developers of proton exchange membrane fuel cells.

Ballard's primary focus is developing fuel cells for transportation, stationary and portable uses. The company's fuel cells have powered three Vancouver transit buses in a field trial demonstration since 1998, and have matched the performance of the city's diesel-powered buses—but with no exhaust emissions and with far greater fuel efficiency. Ballard recently completed a similar two-year test program powering three Chicago city buses with equally strong results.

Currently, Ballard is developing its fuel cells for both heavy and light transportation applications, such as buses, cars and trucks. The company has formed an alliance with DaimlerChrysler and XCELLSIS, a division of Ford Motor Company, to develop an efficient, affordable engine powered by the Ballard fuel cell. Since 1993, DaimlerChrysler has produced four generations of passenger prototype cars, a prototype transit bus and a fuel-cell concept for the Jeep Commander, all powered by Ballard's fuel cells. Ford unveiled two fuel-cell prototype vehicles—the TH!NK P2000 and the TH!NK FC5, a methanol-fueled vehicle powered by Ballard's most recent generation fuel cell. Ballard also supplies fuel cells for General Motors, Honda, Hyundai, Nissan and Volkswagen for their fuel-cell vehicle development programs.

Ballard has significantly improved the power density (amount of power produced in a given size and weight) of its fuel cells. The commercialization focus is now on product development, cost reduction and developing volume manufacturing processes. Ballard expects its first commercial products—in portable applications—to be on store shelves in 2001, with the first Ballard fuel-cell-powered cars to be available in showrooms by 2003.

Plug Power has devoted its research efforts toward developing fuel cells as a power source for homes and small businesses. Its refrigerator-sized fuel cell system, which was tested on an upstate New York home from 1998-99, runs on propane or natural gas. Currently, the company is testing beta prototype systems in laboratories and the field. Plug Power is banking on the idea that the fuel cell will appeal to residential and small business customers as a compact, economical, reliable and environmentally friendly source of power. Fuel cell customers will avoid the cost of centralized power plants and their transmission and distribution systems. Also, fuel cells aren't susceptible to outages due to weather or system capacity overload. Excess heat generated by the fuel cell can be used for hot water and heating, bringing efficiency to 80%. Plug Power, in a joint venture with General Electric Corp., plans to produce thousands of residential fuel cell systems for consumers in 2001, according to Gary Mittleman, Plug Power CEO and president.

Other developers of the proton exchange membrane fuel cell include Allied Signal, United Technologies and Energy Partners in the U.S., and Fuji, Toshiba and Toyota in Japan.

Solid Oxide Fuel Cells. This is the least developed fuel cell but it may hold the most promise because of its ability to convert natural gas to hydrogen internally. The high operating These cells could be used in high-power applications, such as industrial and large-scale central electricity generating stations. Solid oxide and proton exchange membrane fuel cells hold the most potential for residential applications, according to a recent report by EPRIsolutions. Global Thermoelectric in Canada, SiemensWestinghouse in the U.S. and Sulzer in Germany lead the way in testing these fuel cells. Global Thermoelectric plans to have the first beta test remote power systems in the hands of industrial customers by early 2001, with residential products following thereafter. Other developers include the U.S.-based companies Ceramatec, Technology Management Incorporated and Allied Signal Aerospace.

Alkali Fuel Cells. This cell is the only type that has achieved commercial success in competition with other power sources without special funding from research organizations or for environmental reasons. The high power density of this cell and its ability to produce water as a by-product led to its success in the marketplace. However, this cell is used to power space vehicles—a very small niche market. The cell is costly to produce because the electrodes require very high platinum loadings to produce adequate power. A further problem is that the potassium hydroxide electrolyte reacts with carbon dioxide in the air to form potassium carbonate, which degrades the electrolyte and precipitates out and clogs the pores of the electrodes. A European company, Zevco (www.zevco.co.uk), claims to have overcome this and is developing alkali fuel cells for vehicles.

Molten Carbonate Fuel Cells. This high-temperature cell is being developed for stationary power applications. The primary problem with the production and operation of this cell relates to the design of the electrodes, which use a nickel catalyst. The electrodes must withstand working for long periods in the electrolyte (a mixture of lithium and potassium carbonate) which is hot and corrosive. Energy Research Corporation and M-C Power are the leading U.S. developers. Both companies have constructed fuel-cell powered manufacturing facilities with capacities of 2-17 MW per year as part of their research.

Homes in which electric power and heat are produced on-site. Vehicles that are nearly emissions-free. What was once science fiction should become reality in the next few years. Numerous fuel-cell developers worldwide are working hard to make it happen.

About the author:Swirbul specializes in writing for the hydro-electric industry, as well as for business-to business and business-to-consumer Websites. She can be reached at cswirbul@unicom.net.