Posted: Jan 20, 08 2:42pm

For your consideration, from:
http://www.nasa.gov/mission_pages/exploration/mmb/lunar_fuel_cell.html

NASA's Glenn Research Center in Cleveland is leading an effort to develop systems that could store energy for use during the long, frigid lunar nights. The solution may be a fuel cell system that originally was designed for a high-altitude solar-electric airplane.

In 2005, Electrical Engineer David Bents and his team at Glenn demonstrated the first and only fully closed-loop, regenerative fuel cell ever operated. Though the technology never was implemented on the airplane, Glenn engineers are gleaning valuable information from the project as they design a next-generation regenerative fuel cell for the moon.

How It Works:
A typical hydrogen fuel cell combines hydrogen from a tank and oxygen from the air to produce electricity, leaving water and heat as its only byproducts. A regenerative fuel cell also works in reverse, using electricity to divide the water into hydrogen and oxygen, which are fed back into the fuel cell to produce more electricity.
"What makes our regenerative fuel cell unique is that it's closed loop and completely sealed," Bents said. "Nothing goes in and nothing comes out, other than electrical power and waste heat. The hydrogen, oxygen and product water inside are simply recycled over and over again."

In other words, instead of using oxygen from the air like other regenerative fuel cells, the closed-loop system re-uses the oxygen extracted from the water. That makes it ideal for use on the moon, where there is no oxygen.

"On the moon, you would start with a tank of water. You'd use the solar arrays to make hydrogen and oxygen during the day, then use the hydrogen and oxygen to make electricity during the night when there's no sun," said Bents. "Ideally, if nothing broke and nothing wore out, it could run forever without being refueled."

The system is very similar to a rechargeable battery, but it can store four to six times more energy than a battery of the same weight.

An Energy Storage Milestone
In the summer of 2005, Glenn demonstrated the first fully closed-loop regenerative fuel cell ever operated. It completed five continuous day and night cycles. That's nowhere near forever, but at the end of the demonstration, it had not leaked and was capable of running at least one more cycle.

PIMBY
Please, In My Back Yard!