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14 July 2022

e-Zinc unhurriedly chasing long duration with 3+ days storage

We bumped briefly into e-Zinc of Canada a few weeks back and went back for a chat with its CEO James Larsen, which Rethink Energy customers can view in our “forecast and data” segment as a video interview.

e-Zinc is an innovative alternative battery start up, hailing back to 2012, but only getting its first real funding 2 years ago and followed that up with $25 million of funding for pilot manufacture this year.

It is a hybrid battery with the charging cycle decoupled from its discharging cycle. Larsen talks about de-coupling power from energy. In effect the charging process is based on the well understood electro winning cycle used in mining circles to purify metals, and the discharging cycle is a zinc air battery. So these are on different circuits and are different reactions.

What connects them is basic gravity. A set of wiper blades wipe any dendrite growth zinc off the charging electrode, and it falls into a separate pile of zinc at the bottom of the battery. Air is released into the lower segment when the zinc air reaction needs to be started for discharge. Pumps cycle the electrolyte to ensure even concentration, and these require some parasitic power load.

Larsen described the wiper blades as similar to parabolic skis which wipe either side of the electrode at a rate of 1 minute for every hour of charging, so it is a very low load.

The company boasts that it is a long duration storage system, and offered the graph below to demonstrate, from a wind application where it is ideal to use it.

The data is from a live implementation of the e-zinc technology supporting a wind farm. The dark blue is the load, the lighter blue peaks are the amount of wind energy from nearby wind farms , and the shortfall covered by the e-Zinc battery shows constant usage for up to 3 days at a time, when wind output does not reach the load. The dotted line is the battery’s state of charge at any point.

As such Larsen refused to draw a comparison between e-Zinc batteries and lithium ion, saying that the number of discharges are not the issue, but the number of discharge hours is the best way to compare apples with apples, and he says at present that his batteries can offer 5,000 hours of discharge, and this is only limited by the air cathode, so presumably he could change that and the battery could go on working. Larsen says this is enough for three years of operation, and that the company should reach 5 years later this year, and has the eventual aim of getting to 20 years.

Most zinc batteries fail because of short circuits introduced as they try to reverse the initial reaction, which forms dendrites. Without the wiper system, this would happen to the e-zinc battery. It seems a pretty obvious engineering solution to what most chemists find a tricky problem, but that’s often the way.

Larsen feels that the company has until 2030 before the long duration energy storage market gets under way at full speed, although we encouraged him to think more short term, and come to market with a fully automated factory quite soon.

Larsen thinks in phases or chapters, phase 1 was build a prototype using hand tools and hand assembly which validated the process, and the $25 million is to build pilot scale manufacturing, using soft tools that may not last, but which allow you to put fresh learnings into the manufacturing process which is how e-Zinc will operate for the next two years, until the 3rd phase, hard tools and heavy levels of automation to cut manufacturing costs dramatically.

He anticipates going for a funding round for fully automated manufacture in two years, and believes e-Zinc will be ready to compete economically at the grid scale at that point, with another funding round of $100 million to $150 million.

Until then his target customer are communities that rely on diesel for power, where his process is already economic due to the high price of diesel and its distribution costs.

Larsen is convinced that long duration is a separate technology from short duration, and as grids become 60% to 70% powered by renewables they will need multiple day duration longer scale batteries, which he sees emerging in the US in the late 2020s. So he’s not in a rush.

But the learning curve will need to be well advanced long before then, because lithium ion will continue to fall in price over that time, and if he lets it get away from him, Larsen will find the price difference will be too large to make up and that most investors will back solid station lithium ion technology when it arrives, out of habit, unless there are clear advantages in price from something new.

Watch the full 39 minute interview here.