Apparently, this company (EOS) has overcome the recharge limitation that exists in conventional zinc-air batteries, and supposedly has several patents on the technology. If true, this technology would be a big boost for all sorts of battery powered technology, not just grid storage. The big question: what is the conversion efficiency? – Anthony

Guest post by Mathias Aarre Mæhlum

Illustration of Eos Aurora, the first zinc-air utility scale battery by Eos Energy Storage. It delivers in a 40 foot standard shipping container.

In the next few years, an increasing amount of wind turbines and solar panels is expected to be built all around the world, reducing the stress that coal, fossil fuels and other polluting methods of harnessing energy does on our environment.

There are several challenges related to the electrical grid we face when solar, wind and other renewable energy sources reaches 10, 15 and 20% of the total useful energy generated. This article focuses solely on energy storage. Why is energy storage important?

Wind and solar energy (other renewable energy sources as well) are highly fluctuating. We are having a hard time predicting the flow of the energy resulting in two main problems:

How can we assure that we have enough energy to satisfy the rate of consumption? Imagine days where the amount of energy harnessed does not reach the demand.  Or if we flip the coin, days where we generate too much electricity and want to store the surplus for times when energy is scarce.

A stable flow of energy is also important. If we are to exchange our current base load energy systems with renewable energy sources, we need some kind of device between the electricity generation and consumer, ensuring a stable and controllable flow.

Batteries have previously not been applicable for utility-scale energy storage. There are several reasons for this, but most important is the price tag. In the last ten years, technological advancements have been made in a battery that utilizes zinc and air as reactants. The key here is that the air comes from the outside rather than acting as a reactant within the battery.

This result in one very interesting thing: Since there is only one reactant in the battery itself, we can expect an increased energy density. In theory, this can be up to ten times the density of ion-lithium batteries. In addition to this, zinc-air batteries are expected to have a lifetime of 30 years. This things all help with lowering the costs, allowing us to use the technology on larger scale.

It looks like zinc-air batteries on utility-scale could be a valuable addition to our renewable energy systems and help us transition towards the smart grid. The first utility-scale zinc-air batteries are promised to be on the market within 2013: