Is zinc the answer to all our problems?

A small, but growing number of companies say that the 30th element on the Periodic Table could go a long way toward solving one of the most vexing problems in the renewable world: energy storage (see Green Light post).

Switzerland's ReVolt Technology, which received 10 million Euros ($14 million) in a second round of funding today, is the latest to promote zinc as a storage medium. The company makes zinc air batteries. In these devices, zinc powder or pellets are placed in an electrolyte solution. When the solution is exposed to air, chemical reactions take place that cause electrons to be released. In all, ReVolt has raised 24 million Euros.

Zinc air batteries could store four times the amount of power that lithium-ion batteries, claims the company, but would be far more stable, resistant to short circuits, and wouldn't lose much of their charge over time. In some ways, the batteries function more like fuel cells than classic batteries because they get "recharged" by the addition of chemicals rather than getting plugged into a wall.

Another big benefit: Zinc oxide, the stuff found in sunscreen, is one of the byproducts of the zinc air battery reaction. It can then be reformed into zinc for fuel, according to PowerAir, a U.S. company that spun out of Lawrence Berkeley National Labs and is trying to do the same thing.

"Imagine a fuel that, rather than burning up and polluting the atmosphere, can be recycled to use over and over again. Zinc is that fuel and has the potential to replace traditional fuels to power the world," says PowerAir's Website.

Zinc is also abundant and cheap. Pennies are 97.5 percent zinc.

Both Revolt and PowerAir will first try to gain traction into consumer markets and later tackle industrial ones. Zinc batteries, for instance, could replace diesel generators as a backup power source for cell towers.

Others are thinking of bigger applications. Researchers at the Paul Scherrer Institut are looked at ways to use zinc as a way to store heat atsolarthermal power plants. In the proposed SolZinc process, heat from the sun (along with a dash of carbon) would create zinc oxide and carbon monoxide. Zinc could then be used in air batteries or to make hydrogen.

Energy storage, along with clean coal, is often referred to as the "Google" of greentech. That is, an opportunity so huge that the company that cracks the formula will reap billions. Solar and wind farms need local storage so that they can provide power on a more consistent basis to the grid. Much of the wind power produced at night could be more effectively and economically consumed if it could be stored until daytime.

Other solutions for megawatt scale being discussed include sodium sulfur batteries, "flow batteries" from companies such as Deeya Energy, methanol fuel cells various lithium batteries, and caves filled with compressed air. In the consumer world, a whole host of companies like Boston-Power and A123 Systems are tinkering with new types of lithium batteries

Going mainstream with zinc, however, will take time. PowerAir only began to sell its first devices at the end of last year with fairly limited distribution in the consumer market. You can buy them in the SkyMall magazine next time you fly.

Meanwhile, two U.S. companies concocted zinc rechargeable batteries. These devices function more like standard batteries. PowerGenix makes a nickel-zinc battery. (You've read the story-Now see the film.) Ritz Camera began marketing these batteries under its own brand (Quantaray Super Z) at the end of last year.

Soon, a major notebook vendor is expected to announce it will adopt ZPower's zinc silver rechargeable batteries for a laptop.