Sidebar: Testing Fuel Cells at China Lake, June 2003

sidebar:
testing fuel cells at China Lake

The U.S. Navy, which generates electricity from sunshine in the California desert, is trying a new way to store energy for use when the photovoltaic panels shut down for the night. Instead of batteries, there is a system built around a fuel cell. Electricity generated during the day powers an electrolyzer, to make hydrogen fuel from water. When the sun is no longer generating electricity in the panels, the fuel cell kicks in.

The test unit is at Naval Air Weapons Station China Lake, a large tract of arid federal real estate in California. The station needs electricity in various parts of its 1.1 million acres to power things ranging from communication receivers to warning devices that keep wanderers from straying into the line of test fire. These are remote places, out of reach of the grid and difficult to reach at all. According to Doris Lance, a spokesperson for the station at China Lake, travel between sites inside the Naval reservation is measured in hours—say, a two-hour drive and another hour of hiking.

Not only is it hard to truck fuel out to those sites, but they are environmentally sensitive, so a spill could prove disastrous. Given the desert sunshine, solar has been a good way to go.

Fuels cell combined with electrolyzers may replace battery rooms at the Navy's solar energy sites at China Lake in California.

The only catch has been the batteries, which store energy to use when the sun goes down. According to Sam Edwards, systems engineer for the renewable energy office at China Lake, a battery room can be 40 feet square. Maintaining the batteries can tie up two people in a battery room for three days a month, he said.

The system is linked to a solar array capable of generating 7,000 to 8,000 watts of electricity during the day. Excess electricity, power not needed to run external electrical devices, is used for electrolysis of water.

The electrolyzer, from Proton Energy Systems Inc. of Wallingford, Conn., uses a proton exchange membrane and electricity to break down water into its constituent parts. David Wolff, Proton's vice president of marketing, called the process "a fuel cell run backwards."

Earlier this year, Proton landed a $375,000 contract to package the system. Proton was hired through the Ridgecrest, Calif., office of Jacobs Sverdrup Technology Inc., a contractor to the Navy.

The hydrogen is stored at 200 psig (almost 1,400 kilopascals above ambient) in a 2,500-gallon exterior tank for use in a 1 kW fuel cell made by Ballard Power Systems Inc. of Burnaby, British Columbia.

The fuel cell system isn't exactly portable. Not counting the tank, which can hold just a little under 10,000 liters, the system is housed in a cube 8 feet on a side at 5,000 pounds—about 2.4 meters in each dimension at almost 2,300 kilograms. It is transportable, however. According to Edwards, the unit is designed to be taken to a site where it will stay. The overall system design, including control electronics, was handled by Northern Power Systems Inc., based in Waitsfield, Vt.

The area of the desert is called China Lake, but the lake itself is dry. There is very little ground water, and water is at a premium. The water that is the source of the hydrogen will run in a closed system. Hydrogen passing through a fuel cell combines with oxygen to form an exhaust of water, which can be recycled for electrolysis.

As Edwards explained, "If I didn't want to be trucking fuel out there, I certainly wouldn't want to truck water."

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