By Paul Sharke, Associate Editor

Until a year ago, when police and office workers at the Central Park precinct station in New York ran the copiers, they sometimes had to shut off the air conditioners. Computers struggled night and day against the vagaries of unreliable power. Plans to install an electronic booking system were going to remain merely plans until the station's electrical woes could be resolved.

At the Onsi plant, one employee checks the deionization system; the reformer sits to his right. In back, another inspects a second unit before the doors go on.

The New York Power Authority, which supplies electricity to public places in New York's five boroughs and nearby Westchester County, faced a number of obstacles on its way to revamping the power supply at the 128-year-old station. Location was the biggest concern. Formerly a stable, the station is smack in the middle of the park, about as far away from the street and the services below as one can get in New York.

The obvious solution—running a new line in from Fifth Avenue or Central Park West—would cost $1.2 million, likely undergo a lengthy permit process, and possibly spoil during construction one of the last refuges of open space in a land built overbearingly plumb. A gas turbine generator could meet station needs, but not without disturbing the peace. Photovoltaics could meet demand also, but only by first transforming the building's facade, a no-no for historic landmarks.

It is this kind of niche that International Fuel Cells and its sister company, Onsi Corp., of South Windsor, Conn., fill with their 200-kW phosphoric acid fuel cell power plants. At $800,000 for a system (which comes to $4,000 per kilowatt), the Onsi units are not exactly competitive with the capital cost of grid power. For supplying power where infrastructure is old, though, or lacking altogether, where system reliability is especially important, or where a high-quality electrical source is needed, the fuel cell is a contender, said Onsi marketing manager John Trocciola. The Central Park station, it just so happens, met all three conditions.

"Onsi units are available commercially," said Trocciola, "meaning they come off an assembly line at a rate of three or four a month and are backed by a team of service personnel." The standard Onsi PC25 power plant is offered in one flavor: a 235-kVA, 480-volt, three-phase, 60-hertz model (or 400 V, 50 Hz) that delivers, as a bonus, more than 700,000 Btu of heat per hour. Of this, approximately 325,000 Btu per hour is available at 250¡F, enough for 20 tons of absorption air conditioning. The balance of 375,000 Btu per hour at 140¡F can be used for space heating or boiler preheating, or for making domestic hot water. If the heat is not used, auxiliary dry cooling towers can transfer it to the atmosphere. With an electrical efficiency of 40 percent, fuel cells equipped for heat recovery reach efficiencies of 85 percent, Trocciola said.

The fuel cell was invented by William Groves in 1839, but it has been only in the past few decades that the technology has received much attention. Onsi is something of the old man in this industry, having provided fuel cells for the Apollo moon missions of the 1960s.

Onsi's phosphoric acid units, while different from alkaline fuel cells used aboard spacecraft, remain the most mature of the fuel cell technologies in use today for stationary power. Indeed, for 15 years Onsi has been developing and manufacturing phosphoric acid fuel cells, thanks to programs started by the Department of Energy with the help of the Gas Research Institute, along with utilities, gas suppliers, and various user groups. Today, as the commercialization of phosphoric acid fuel cells proceeds, other companies explore high-temperature solid oxide or molten carbonate technologies.

For the Central Park project, the federal government contributed about a third of the equipment costs through a grant program administered by the Department of Energy. The police station project is one of a hundred similar fuel cell projects whose expenses the DOE has partly borne. "The goal is to encourage mass production that will bring down the cost of the units to a range more competitive with other, more traditional electric power generators," said a DOE spokesperson.

Unlike polymer electrolyte membrane fuel cells under investigation for automotive power plants, the amount of platinum in the Onsi phosphoric acid cells represents a mere sliver of their cost—$30 to $40 per kilowatt, according to Trocciola. "There are no exotic materials used in our equipment," he said. "It's mostly graphite."

Asked to project eventual costs for these fuel cells, Trocciola said that through a combination of increased production volumes (the Onsi plant uses about a fifth of its capacity), strides toward "a commonality of parts" among its suppliers, and lowered costs for balance-of-plant equipment, like pumps and pressure vessels, he thought that $1,500 per kilowatt was within reach.

Onsi has nearly 200 units installed, using as their energy carriers natural gas, butane, or gas produced in wastewater treatment. In every instance, the gas is processed through an external reformer, which converts it to hydrogen and carbon dioxide. "Unlike microturbines, our fuel cells operate on low-pressure gas," he added.

Natural gas reforming requires water. The fuel cell itself takes care of this, producing water during the electrochemical reaction. A makeup system can draw water from other sources for hot days, when the reformer needs more than the cell stack generates.

The New York Power Authority commissioned the system in April 1999. According to Yan Kishinevsky, a senior research and technology development engineer there, the fuel cell has since exceeded projected availability. "Onsi rated the fuel cell for 95 percent availability," Kishinevsky said, "and we're at 96 percent."

In a fuel cell plant under construction, the dc to ac converter is in front, the cell stack to its left, and the low-temperature shift converter one frame over.

Both NYPA and Onsi monitor the plant remotely, Kishinevsky said. No operators are required on-site to oversee plant operation. "Maintenance has been at an absolute minimum," he added. So far, NYPA has had only to replace beds and filters in the water treatment system and filters in the air intake, which it did without taking the unit offline. Future scheduled maintenance includes annual two-day shutdowns to inspect pressure vessels, relief valves, and motor bearings. Complete cell stack and processor overhauls are required every five to 10 years.

The plant is operating at about 20 percent of its nameplate capacity, but the police department plans to add electric vehicles onto a charging circuit, which should double loading. "That leaves the department plenty of power to add the equipment it has been considering over the next three to four years," Kishinevsky said. Station upgrades will likely include bringing in a heat exchanger to make use of the heat that the unit now dumps, he said.

Despite its success at the police station, NYPA remains committed to central generation and the grid. "We don't see fuel cells as competition for grid power," Kishinevsky said.

Steve Shoenholz, NYPA deputy vice president of public affairs, said that the utility regards fuel cells as a "direct response to a definite problem." That certainly was the case for the Central Park station. In another instance, the authority brought in an Onsi fuel cell to produce power from anaerobic digester gas generated by the Westchester County Wastewater Treatment Plant in Yonkers. Gas that otherwise would be flared off now cuts the use of grid-supplied electricity. Still another Onsi fuel cell at the North Central Bronx Hospital operates in tandem with the grid and as an emergency backup, Shoenholz said.

Bill Miller, International Fuel Cell's president, said he believes decentralized power generation will eventually whittle down the electricity market share now held by large steam stations. He did not think that central generators would ever be eliminated.

Economics will play a definite role in the future of fuel cells. "We substantially reduced the cost of fuel cell power over the last 10 years," Miller said. He thought it would be another three years until per-kilowatt costs reached the $1,500 level.

There is a market where fuel cell electricity competes now, Miller said. In a microelectronics age that has ushered in the need for uninterrupted power supplies, the fuel cell can deliver a premium product with up to 99.99999 percent reliability. For First National Bank of Omaha, knowing that the computers at its new technology center could process credit card data without disruption was enough to convince the bank to buy four Onsi fuel cells as sources of primary power.

Yet, one benefit of fuel cell energy is so obvious that it almost sneaked by here unacknowledged. Fuel cell power is clean energy. According to Onsi product literature, the plant emits 1 ppm NO_x and 5 ppm CO, a mere blip on the California emissions scale for combustion engines, which allows 36 ppm for NO_x and 2,000 ppm for CO.

"The PC25 fuel cell essentially eliminates all oxides of nitrogen, which contribute to smog, and the oxides of sulfur, which create acid rain," Miller said. "As long as we use hydrocarbons for the fuel cells, they will produce greenhouse gases, though only a fraction of those produced through combustion processes."

Put another way, an Onsi fuel cell operating at 200 kW over 8,400 hours will make 1,100 fewer tons of carbon dioxide than an average generator relying on combustion. It will save 40,000 pounds of other pollutants, too. Those kinds of numbers ought to be a big help to New York's Finest in their ongoing battle to keep the park clean.


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