Picking a winner: How VRFBs match up against battery rivals
Special report: Last month a lithium-ion battery exploded in a wind power plant in South Korea causing an estimated $5.5 million of damage, followed days later by a battery fire at a solar power station in another part of the country.
Just a month before, an overheating lithium-ion battery caused a fire at a substation in Gyeongsan in the southern region of the country.
Some Lithium-ion batteries suffer from thermal runaway risk — ask anyone who couldn’t take their exploding Samsung Galaxy 7 phone on a plane — but there are alternatives that are more stable and better suited to certain outcomes.
The main alternative is a ‘flow’ battery which is safer than lithium-ion and more suited to large scale applications, such as network support for electricity grid operators and telcos looking to power off-grid communications towers and utility scale installations.
This is why vanadium focused companies like Protean Energy (ASX:POW) have developed their own vanadium flow battery units to capitalise on rising demand for safer industrial scale energy storage systems.
Protean owns 50 per cent of South Korean vanadium redox flow battery (VRFB) developer KORID Energy, which has patents over technology in the increasingly popular vanadium sector of the battery field.
The right battery for the right use
There are two kinds of flow batteries available in Australia now — vanadium and zinc-bromine.
VRFBs are the cheapest and have the longest life spans, lasting more than 20 years or up to 25,000 cycles. They require little maintenance and can be fully discharged without damage to their storage capacity.
They use two tanks of vanadium pentoxide (V₂O₅) solution that have been processed into a liquid electrolyte.
When the electrolyte is pumped through electro-chemical cells past a proton-exchange membrane, ions are swapped between the negatively and positively charged electrolyte, creating an electrical charge.
The VRFB is inherently more stable than lithium-ion because the electrolytes are just positively and negatively charged version of the same chemical and the process of charging and discharding does not generate excess heat.
They cost between $US580-820 kWh and are being installed around the world for industrial and large scale energy use.
A megawatt is a unit for measuring power that is equivalent to one million watts — or ten cars. A megawatt hour (Mwh) is equal to 1000 Kilowatt hours (Kwh). It is equal to 1000 kilowatts of electricity used continuously for one hour.
In China, Rongke Power in Dalian province is building the largest battery in the world, an 800MWh VRFB, while in Hebei province Pu Neng Energy is building a 500MWh version.
VRFBs have also been installed in Australia, Hawaii, Japan and other countries.
The other option is the zinc-bromine flow battery. It’s a bit more expensive upfront, costing between $US800-900 kWh but can only hold between 3-10 hours of charge, and has a 10 year lifespan or up to 10,000 cycles. It’s more suited to residential use.
Lithium-ion batteries hold about one to four hours of charge and degrade a little each time they’re discharged below 20 per cent of their capacity. They have a life span of about 7000 cycles or up to 10 years with careful use.
They’re great for quick bursts of energy such as going from 0-100km in a car.
In Australia, zinc-bromine batteries are yet to really take off but VRFBs are gaining a foothold in the mining sector, large scale renewable energy and among industrial users.
Protean Energy (ASX:POW) is one company which is beginning to test its VRFB in Australia, setting up a 25kW/100kWh V-KOR battery at industrial fittings supplier OzLinc Industries in Perth in May.
It was switched on in June, and is made up of two electrolyte tanks, two battery stacks of 12.5kW each, one 25kW inverter, electrolyte pumps and a power management system.
The whole unit is charged from a 21.1kW rooftop solar system.
Part of the reason why VRFBs attract large scale users is because they can be scaled up or down simply by adding or removing tanks, with the largest VRFB currently having a 200MW/800MWh capacity.
They are going up against VSUN Energy, the company that launched Western Australia’s first VRFB in 2016, but it’s still a very immature market with few other companies operating in that space.
This special report is brought to you by Protean Energy.
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