From Ancient Batteries to Today's Fuel Cells

August 17, 2003 – Vol.8 No.21

FROM ANCIENT BATTERIES TO TODAYS FUEL CELLS.

According to unconfirmed reports, the mysterious Baghdad Batteries are among the missing in the looting of Baghdad’s National Museum of Iraq.

The name Baghdad Battery might be a bit of a misnomer. Scientists agree that the more-than-2000-year-old artifacts are a kind of electrochemical cell. They’ve proved it by replicating and testing the 5-inch tall clay pots containing an iron rod suspended in a copper cylinder. But scientists don’t mention if these so-called batteries were for a one-time use and thrown away, or possibly refueled. (Recharging would have been out of the question, one presumes.)

If they had been used once then discarded, a significant amount of labor in building each cell would have been wasted. But if users at the time simply replaced the iron rod (its sacrificial anode) with a fresh, non-corroded one, along with fresh electrolyte (thought to be wine or grape juice), the cells would have continued to generate small amounts electric current.

Had this method been employed - each cell refueled with a new iron rod - the Baghdad Batteries would have to be renamed Baghdad Fuel Cells.

The long-distant relatives of the Baghdad devices today are metal-air fuel cells - electrochemical cells refueled by the replacement/recycling of zinc, aluminum, magnesium sacrificial anodes. These devices, while not receiving anywhere near the attention of hydrogen fuel cells, are showing considerable promise as green power for vehicular, portable and stand-by power applications.

Arotech (also known as Electric Fuel Corporation) has announced that its zinc-air fuel cell powered, full-sized city bus has achieved a new record of 145 miles before refueling. The bus was tested through a program with the U.S. Federal Transit Administration in a stop-and-go driving cycle equal to that used in bus transit service. The record was a 14% increase over the last testing in 2002 and a 43 percent increase over the the same test in 2001. The increase in range was attributed to improved ultracapacitors used for regenerative braking, along with the installation of a new energy management system.

PowerZinc Electric has announced that its zinc-air fuel cells have proven superior in a number of aspects compared with lithium polymer and lithium ion batteries when tested by a major Japanese automaker. (PowerZinc, wisely so, won’t divulge which.)

In testing PowerZinc cells were the most energy dense in terms of weight at 220 watt hours per kilogram (Wh/kg) compared with 97.3 Wh/kg for Lithium Ion (Li-Ion) and 77.8 Wh/kg for Lithium Polymer.

In cost comparison, the zinc-air technology now stood at $100 per kilowatt hour (kwh), which could drop to $50 /kwh, whereas Li-Ion stood at $1140 /kwh, expected to fall to $360/kwh. Cost comparison with Lithium Polymer was not released by PowerZinc. The zinc-air technology also outperformed the others in low-temperature performance - critical to commercialization of the technologies in cold climates.

For Baghdad Batteries visit World-Mysteries at http://www.world-mysteries.com/sar_11.htm , Arotech at http://www.arotech.com/ , and PowerZinc at http://www.powerzinc.com/ .