Think Zinc
John C. Dvorak, Forbes Magazine, 06.11.01, 12:00 AM ET
forbes.com
Zinc-air's beauty is in its density. The technology, invented during World War I by
Parisian Charles Fery, relies on immersing zinc in a solution of potassium hydroxide,
which then oxidizes upon contact with air. The electrons released can be
harnessed as electricity. You can get about 110 watt-hours out of a pound of zinc.
Lithium-ion rechargeables hold up to 60 watt-hours per pound. A lead-acid car
battery holds only 20. Zinc-air's earliest use was for powering telephone lines where a
slow drain was acceptable. The most common use today is for running
hearing aids. A Teflon casing permits a modest amount of air to pass through,
allowing the battery to last a week.
Use by bus fleets, which can replenish fuel cells in a central location, makes more
sense than use by the general public. The idea of setting up a national network of
"zinc stations" sounds impractical. That problem may be solved by developing a
totally enclosed rechargeable fuel cell. At least two privately held California
companies, the Carlsbad-based Metallic Power and Livermore-based Power-Air
Technology, hope to achieve this soon.
Not knowing what this stuff will cost doesn't stop the talk of grandiose schemes.
Power-Air, for example, dreams about fueling scooters in China, creating backup
systems for homes and amusement parks, powering fork lifts and buses in Mexico
and China. Meanwhile it hasn't sold a thing. Zinc-air technology has a bright future,
but we need to see more real products. |
