Out of its offices in Brisbane, storage company Redflow developed the world’s smallest zinc-bromine flow battery. Now, the company has taken its core offering and redesigned it for the purposes of mass production, set on becoming a frontrunner in what the company’s CEO and Managing Director, Tim Harris, sees as major shift in the energy storage market.
“I think there’s increasing recognition that there are many different technologies around energy storage and perhaps lithium is not the answer to all the needs of the market, especially as the market is moving away from that sole focus on grid stabilisation and FCAS type markets to solar-shifting,” Harris tells pv magazine Australia.
“There’s a drive towards demonstration of renewable energy throughout the day, which is where medium-duration energy storage really comes into its own.”
Flow batteries – a brief explainer
Flow batteries are an intrinsically different beast to the predominant lithium-ion batteries, the domain of giants like Tesla. Lithium-ion batteries are what’s known as solid-state batteries, storing energy in metal. Flow batteries, on the other hand, store energy in electrolyte liquids. They are usually designed to have two tanks, one containing a positively-charged anode and the other with a negatively-charged cathode, separated by a membrane.
Using liquids allows flow batteries to produce electrical currents without degradation, giving the batteries a longer cycle life and allowing them to store charge for longer periods compared to lithium-ion batteries. Flow batteries can also be fully discharged without damage, and are easily scaleable – able to be fitted to one another to increase capacity.
Flow batteries also lend themselves to recycling, which is an aspect Harris thinks will become increasingly relevant for Redflow’s overall offering – especially given just 2% of Australia’s annual 3,300 tonnes of lithium-ion battery waste is currently recycled.
Their pitfall? Size. Tanks of fluid can, by nature, only be made so small. Which is part of the reason lithium-ion batteries have been far quicker out the gate – we’ve needed small, high-powered batteries a lot longer than we have utility-scale ones. Despite being arguably less well suited for larger scale applications, lithium-ion batteries have benefited massively from their ubiquity and visibility, having been used for decades in our phones, laptop chargers and now in our EVs.
Yet, as Harris notes, lithium-ion technology start to lose their commercial attractiveness when it comes to storing energy for more than four hours. “That leaves a gap for medium-duration storage companies like us to address.”
Filling the gap with a next generation of flow
And address it, they have. The first three months of 2021 have already been huge for Redflow – it began customer trials for its new Gen 3 model and it closed its biggest sale to date, selling 192 of its zinc-bromine flow batteries to waste conversion specialists Anaergia for $1.5 million.
“It’s been a pretty exciting couple of months for us,” Harris says.
The company’s growth spurt (Redflow has sold 1.2 GWh of energy to customers to date) comes after a period of pandemic-induced hibernation. “Gen 3 has been in the works for sometime but Covid has allowed us to spend time and resources on that,” Harris explains. “It’s a major milestone for us. It’s our key vehicle to get costs out of the battery.”
Redflow’s next generation model has seen a major design overhaul from its previous ZCell and ZBM2 models. Its new model includes a single rather than double stack design, tanks which sit side by side, a new electronics board and cooling system. The changes have all been made with the goal of mass production in mind, with the company aiming to get 30% out of the price through the reengineering and supply chain savings.
“Customers won’t see a difference, it will still be a 10 kWh battery but the supply chain savings we can make and the simplicity around production and manufacturing of our battery is a major advancement.”
The company expects the Gen 3 to be in full production by the second half of this year, with its eyes on further driving down costs through economies of scale. “As we start to produce that Gen 3 battery, in manufacturing them we clearly think there’s further savings that we can get to as we ramp up volumes.”
The batteries are currently manufactured in Chonburi in Thailand, an automotive manufacturing hub southeast of Bankok. Redflow relocated its production there at the start of 2018, drawn by the parallels between its own processes and the skills needed to manufacture cars. “It’s a very high quality labour force we’ve found there,” Harris says.
“[Our] facility now, we’ve designed that to do up to 60 MWh, so its flexible in terms of the next growth ambition that we have.”
Nonetheless, Harris isn’t ruling out shifting or partially shifting Redflow’s manufacturing base – especially as the company explores a new frontier: automation.
Automated manufacturing affords greater flexibility
Harris says Redflow is now looking at automating certain processes within its existing manufacturing approach.
“We think there’s a lot of opportunity for us to do that and we haven’t really touched the sides of the benefits from automation in terms of our manufacturing yet… and that’s a function of volume manufacturing approaches that we’re excited about.”
Redflow’s batteries are still fairly labour intensive to create, making labour costs an important factor. Yet through automation Harris is hopeful the company can develop its production potential into other markets. “Or even take some of that manufacturing facility, especially elements that can be automated, and relocate it to markets where it’s beneficial for us to do so,” he says.
“So if we saw some major demand here in Australia and there’s opportunities for automation, then clearly that adds to the potential attractiveness of Australia in the future.”
Harris still sees Thailand as good base for Redflow’s immediate growth, but as the company starts to see more demand, questions about moving production closer to its core market have arisen. Currently Australia, New Zealand, South Africa and parts of Asia are Redflow’s main customers.
Eyes on the big wigs
Redflow’s recent $1.5 million sale to Anaergia’s California waste facility has opened up a new horizon for the Brisbane company though. “We want to use the [Anaergia deal] as a launchpad to hopefully expand our presence here in California,” Harris says. “We’ve always had a strategic eye on the US market, it’s one of the biggest markets for storage in the world and its growing significantly.”
As part of the deal, Redflow designed what it refers to as ‘energy pods’ – essentially, an enclosure containing 16 of its flow batteries and the power electronics necessary to operate them. “We think that’s probably the start of the building blocks that we need to go and target larger megawatt hour systems,” Harris says.
“It allows us to step into that higher voltage space that’s going to be necessary for large-scale industrial and commercial and potential utility elements, so that’s a major development for us.”
Different chemistries of flow batteries
Flow batteries come in a range of different chemistries, the most common of which include vanadium, zinc-bromine and zinc-iron. Recently, vanadium redox flow batteries (VRFBs) have been the primary subject of flow battery adoration, finally experiencing market interest after spending decades largely ignored.
Redflow, however, has chosen a different path, opting instead to use a zinc-bromine solution. “Zinc-bromine has the natural advantages over other flow battery chemistries such as vanadium,” Harris says.
Firstly, vanadium, the metal at the batteries core, has seen significant pricing volatility recently, which is hardly ideal for manufacturers. “The second thing we have is higher energy density and efficiency than vanadium systems,” Harris says.
Anaergia apparently considered using vanadium flow batteries at its facility, before settling on Redflow’s zinc-bromine solution – with Harris saying Redflow’s solution was better able to meet the facility’s available footprint.
As just one of a handful of zinc-bromide flow battery producers in the world, too much competition is far from the company’s main issue. Given that, Harris relishes the success of any chemistry of flow battery, noting increased market acceptance ultimately benefits all flow battery producers.
The CEO is eager to see Australia to realise its potential as a clean energy powerhouse and an exporter of leading edge products. “There’s a fantastic opportunity for Australia as a nation to embrace that.”
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