Iron-Air Cell, the Metal-Air Battery Variant for Renewable Energy System Storage

Metal-air batteries, as I have previously discussed, are batteries that rotate around its energy charge and discharge cycles using oxygen in the air as the cathode. They are essentially “breathing batteries”, capable of significantly extending the capacity and lifetime of a battery, since oxygen can simply be extracted anywhere as the battery operates (and not just stored in a limited amount inside the electrochemical cell).

There are many variants of metal-air batteries, each using a different metal for the electrolyte. Iron-air electrochemical cells might be considered as one of the oldest types, but a new variant design of the technology now has researchers proposing its application for solar and wind system energy storage.

The basis for the design of this new iron-air battery variant counts the fact that most of the materials used to create it are cheap and quite easy to find. This in turn makes mass production for it quite easy, and it could be made with economic feasibility perfectly within reach. Its basic working principle makes use of the chemical energy generated when iron plates experience oxidation when exposed in the air (a chemical process that is quite similar to rusting).

The team of developers that created this iron-air battery variant is led by Sri Narayan, a professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences. Actual numbers and figures of its specifications are not yet specified, but according to this official press release, their iron-air batteries have the capacity to work between 8 to 24 hours straight (that’s just one unit). It also claims that the new batteries are at least 10 times more efficient than older iron-air battery variants. This efficiency is attributed to the addition of bismuth sulfide, a compound that is used to prevent the battery from producing hydrogen wastefully during its electrochemical process.

The new iron-air battery variant has been observed as a potential replacement for traditional deep cycle batteries for battery banks due to the following promising advantages:

• Larger Energy Capacity – as mentioned earlier, metal-air batteries last longer significantly with the use of oxygen. Further development of the new iron-air battery variant might even extend its capacity a few times longer than what it can already do (negating the intermittency problem of renewable energy systems).
• Easier To Produce – cheap and easy to find materials make it equally cheap and easy to make. In addition, iron is also relatively easy to extract and recycle from trash. Manufacturing costs might lessen the impact of this advantage, but this still does not change the fact that iron and oxygen are in great abundance on this planet.
• Higher energy density, thus more power per unit weight – this is the default “feature” of all potential metal-air batteries. You need to use only a few iron-air batteries to build your solar/wind system battery bank, unlike regular deep cycle batteries which not only require more units, but are also considerably heavier by default.
• More Environment-friendly (raw material-wise) – Deep cycle batteries use lead-acid as its electrolyte, so it is not actually that environment-friendly. Although Sri Narayan’s team previously considered the use of mercury to improve their battery’s efficiency, they immediately dismissed the idea, as it would defeat the eco-friendly purpose of battery’s design.

The primary disadvantage of most energy dense batteries today is their price. While lithium-ion batteries can be practical for gadgets and EV’s, they are not particularly economical for use in a considerably large renewable energy system. With the help of advanced iron-air batteries in the future, we can merge the best points of lithium-ion and lead-acid batteries, possibly changing our view about off-grid renewable energy systems once again.

Photo credit: Some rights reserved by Voxphoto via Flickr

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Christian Crisostomo (251 Posts)

Christian Crisostomo is just your average tech geek that loves to see man's newest and most recent technological exploits. He holds great interest in the potentials of green technology, and is enthusiastic about the continuous development of environment-friendly alternative energy.

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