The Salamander of myth and legend: a creature which lives in water but renews its life in fire. It’s rubbish, Bunkum, steaming horse manure… a bit like an electric car with neither plug nor solar panels.
Except no one’s told those clever boffins over at Advanced Power and Energy Sources Transportation (APET) in Hong Kong. According to them, the Salamander and the cordless EV are about to step out of myth and into reality.
APET’s revolution centres upon how zinc air batteries can power EVs. The technology is proven on the small scale: hearing aid battery adverts dominate any Google search for “zinc air battery”.
Furthermore, as zinc air batteries need only zinc, air and water to produce electricity they are likely the most environmentally friendly ones around.
However, upscaling the technology from a hearing aid to a car has always been a problem.
There are four traditional problems with zinc air batteries. APET’s Zinc Oxygen Energy (ZOE) system appears to have cracked them all:
Weight – The usual materials needed to create a zinc-air battery have always been heavy. APET have totally rethought the battery’s design, resulting in a battery which has twice as much Wh/kg (watt hours/kilogram) than a lithium-polymer (Li-Po) solution and four times as much as a nickel-metal hydride (NiMH) one.
Cost – The traditional materials have also always been expensive, affordable only by the military. The same redesign has yielded a phenomenal reduction in price, with the production costs of a ZOE battery now estimated at one-tenth of a Li-Po solution and one-fifth of a NiMH one.
Reusable – Zinc air batteries have always had one problem: once the zinc inside has been exhausted, they’re dead and cannot be recharged. Most current zinc air solutions are made to be disposable (albeit biodegradable as well). The ZOE battery is designed to allow the casing to be taken apart and reused with a fresh batch of zinc.
Rechargable – Hang on, didn’t I just say that zinc air batteries cannot be recharged? Well they can’t, not in the traditional “plug it in” sense of the term. However, it’s an easy process to turn the waste zinc oxide back into zinc… all you need is heat (and lots of it). For this, APET have proposed building solar furnaces which will capture and concentrate enough of the sun’s heat to perform the chemical reaction.