Zinc-bromine flow battery technology addresses safety issues Tuesday, 06 December 2016

The Clean Energy Council says energy storage technologies are a game changer in the energy market in Australia.

But to date, storage solutions haven’t been cost effective and doubts around safety have arisen.

Now a new battery storage system by Redflow that uses zinc-bromine flow battery technology is providing a solution to both of those problems.

Redflow was created when chief engineer Alex Winter saw a common mistake being made when it came to battery research in Australia – attempts to scale-up zinc-bromine flow battery technology to produce large batteries that delivered few opportunities for mass production benefits.

Winter and his brother went on to purchase equipment and intellectual property in Germany and brought it back to Australia to form the basis of the Redflow business.

But rather than try and build large batteries, Redflow focused its attention on smaller form factors with its core commercial products, ZBM (zinc-bromide module) batteries.

“Individual ZBMs could be harnessed together to create large-scale energy storage systems as required,” said Simon Hackett, Redflow CEO and executive chairman.

The 16-year-old company, which listed on the Australia Securities Exchange in 2010, has now designed the world’s smallest zinc-bromine flow battery.

The most recent iteration is the ZCell, which was designed for stationary energy storage in residential, commercial and grid-scale applications.

It includes two storage tanks filled with different zinc bromide-based electrolytes and weighs about 240 kg.

“The zinc bromide electrolyte is pumped past two electrode surfaces that are separated by a microporous barrier. During the charging phase, the anode converts zinc ions in the solution to zinc metal, which forms a coating on the electrode, while the cation converts bromide ions to bromine,” Hackett said.

The reverse occurs during discharge.

“Redflow’s ZCell battery has a 10 kWh capacity and can discharge 100 per cent of its charge without degrading its performance or battery life,” Hackett said.

Other benefits include reduced fire hazards as ZCell’s electrolyte is fire retardant and mechanical damage that does not pose explosion risks, and even in hot, remote locations, there is no need for external cooling in outside temperature of up to 45 degrees Celcius.

The battery is also recyclable or reusable, with components made from plastic, aluminium and steel.

Challenges

During the development process, Redflow had to grapple with challenges such as commercialising the technology, funding for the long-term development program and scaling the product up to meet global demands.

“We solved the technology problems by building and maintaining a team of world-class experts in zinc-bromine flow battery technology,” Hackett said.

Meanwhile, listing on the ASX helped to solve financial challenges, and Redflow addressed the manufacturing challenges by outsourcing manufacturing to supply chain solution company Flex, which produces the core ZBM batteries at a factory in North America.

The first ZCell system at an off-grid property was recently installed at a property near Willunga, Adelaide in South Australia, owned by the family of Alan Noble, engineering director for Google Australia and New Zealand.

Mains power was available in only one corner of the hilly 100-hectare Willunga property.

Extending mains power further would have been expensive, so Noble installed two ZCell batteries, which can store 20 kWh of energy, powered by solar panels on the roof of a large shed.

“If there is a bushfire here, we can power our pumps properly, whereas electricity distributor SA Power Networks has a policy of actually shedding power during high bushfire risk days, so precisely when you need the power, they shut it down,” Noble said.

“Without the ZCells, we’d be running around trying to fire up generators during hot days, which is not practical.”

The batteries were integrated with 24 Tindo Solar panels and two Victron battery inverters by ZCell installer Off-Grid Energy Australia and continued working uninterrupted during a recent power failure that blacked out the rest of South Australia, according to Hackett.

Renewable energy challenges

Modelling by the Clean Energy Council in its ‘Energy Storage in Australia’ report in 2012 indicated the potential for a 3000 MW market for energy storage devices by 2030.

“The battery market has started to expand massively, so there’s enough space in that market for a wide range of energy storage solutions to meet diverse customer needs around the world,” Hackett said.

But Hackett said one key challenge is how to deploy energy storage technology so that intermittent energy sources, such as solar and wind power, can be used 24/7, which could spell a boon for Australia.

“This will effectively replace the need for fossil fuel-based energy generators that currently supply baseload power. It is a huge, long-term project that has the potential to deliver enormous benefits for Australia in terms of meeting its carbon reduction goals, both today and in the future,” Hackett said.

“As consumer demand and production volumes grow, manufacturing and distribution efficiencies will drive down costs to make these new batteries more affordable, further driving consumer uptake.”

[Image: Redflow CEO Simon Hackett with the ZCell battery enclosure.]