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Redflow says will compete with lithium, lead batteries on cost

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ASX-listed battery storage company Redflow says its advanced flow batteries are already becoming cost-competitive with some of the market’s top lithium-ion and lead acid offerings, after the company cut the cost per kWh of its zinc bromine technology by over 50 per cent in 2015.

According to a product development update released by Redflow this week (and see the table below), the levelised, or lifetime cost of energy (LCOE) of its ZBM2 batteries is somewhere between 20-30c/kWh, putting it in the ballpark with current top of the range lithium-ion and lead acid battery technologies, including the Tesla Powerwall.

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But the company notes that while lead acid and lithium have got to this place after decades of improvements, manufacturing optimisation and cost reductions, the Redflow battery is relatively new and thus has “substantial scope for further optimisation.”

On top of cutting technology costs, the company has also cut its manufacturing costs by 15 per cent over the course of 2015, and improved product performance, extending the batteries’ life cycle/longevity through a new electrode formulation.

The zinc bromine technology is also said to have other advantages over its more mainstream rivals, including a much reduced risk of thermal runaway and fire; the ability to operate over a wide temperature range with only ambient air cooling, and longer shelf life due to “deep cycling”.

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Redflow’s ZBM product range, from residential to large-scale commercial and utility applications

Redflow – which last week announced plans to launch its residential battery offering in March – says global interest in home energy storage has “been ignited”, with Australia serving as “the key proving-ground for the battery industry.”

The company, which is initially targeting the commercial and grid-scale market, says there are already immediate commercial benefits for early adopters of its technology, particularly for use by Telcos or in off-grid and renewables integration applications.



It plans to begin targeting the residential market in Australia starting in March, and thereafter look to expand its residential offering globally.

Company chairman – and its largest stakeholder – Simon Hackett is overseeing this strategy in his executive role focusing on commercialisation and technology enhancement.

It is developing a “plug and play” model that will allow for simple use. Hackett this week suggested that homes with battery storage will be better placed to stay with the grid, although testing from a Redflow battery in November showed 74 per cent of household energy provided from solar, 24 per cent from Redflow batteries and 5 per cent from the grid.

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  • Farmer Dave

    I’m excited by the potential of flow batteries, and I can see some really helpful niche applications which use their ability to be “recharged” by exchanging fluids in the discharged state with fluids in the charged state from an external source. For example, an electric railway locomotive could be powered by flow batteries. Because volume and weight are not such an issue for railways (particularly for freight transport), the locomotive could house the battery stack and control systems, and a coupled tanker car (or cars) hold the charged and discharged solutions. Depots, stations, etc could be covered with PV and/or use the grid to recharge the fluids. When the locomotive stops, the discharged fluid would be pumped to the treatment plant, and the locomotive replenished with charged fluid, thus very quickly giving it back its maximum range.

    A similar fluids change-over system could work for sea ferries on standard routes; they could simultaneously discharge “spent” fluid and take on charged fluid while their passengers are moving on and off the vessel.

    • Chris Fraser

      Thoroughly agreed there. The ZBM appears to score in terms of stability and safety. It appears that I might be able to use home PV to charge liquids during the day and then ‘refuel’ the EV at home. It could even go some way to placating range-anxious and refuel-quick motor enthusiasts. Perhaps even the local servo could be trusted to retail liquids.

      • Richie

        Please see my reply to Farmer Dave

        • Chris Fraser

          I only wish i understood your chemistry-minded explanation better – though i make that my problem only not anyone elses.Just perhaps … if the electrode could travel around with the electrolyte ? … maybe the portability of the system would improve ? I guess we are some distance from this level of utility.

    • Richie

      Ummm! The source of electrons in the zinc bromine system appears to be (solid) metallic zinc deposited on an inert electrode. Discharge of the battery involves dissolving the zinc into the electrolyte, releasing two electrons per zinc atom. Recharge involves sending a current in the reverse direction to remove all the zinc ions out of solution onto the electrode again. I cannot see how a fluid can be replenished outside the battery and swapped over, much as I like the idea. A recharged electrolyte has no zinc ions in it. So attempting to swap depleted electrolyte (containing all your zinc) with replenished electrolyte (with no zinc in it) would kill your battery. Sorry. BTW Redflow does not make such a claim as you ascribe to their battery.

      • Farmer Dave

        Hi Richie, you may well be right. I confess that in my enthusiasm I had assumed that the chemistry of the zinc bromine system was similar to the chemistry of the vanadium redox flow battery. In the vanadium redox battery, I understand, the only difference between the charged and discharged solutions is the valency state of the vanadium, and only electrons flow into and out of the electrodes. I understand that the zinc bromine system has a higher energy density than the vanadium redox system; it seems that the higher energy density comes at the cost of not making a fluid exchange “recharge” possible.

      • Deco Teague

        In that case, why not swap out the tanker cars for fully charged tankers at the stations? Probably faster than draining/filling such large quantities of fluid.

  • MaxG

    The comparison is flimsy at best. They should have taken — say 10kWh — for each technology, including LiFePO4, and the winner would be the LiFePO4 battery.

    • JeffJL

      Max. There are many variables that could have been put in.

      Say you use the 10kWh comparison. Should you use 13.3kWh for the LiFePO4? (only 75% discharge). Or should you use higher as in 10 years the 10kWh available would be less due to degradation of the battery.

      I think the LCOE is the best gauge. The figures quoted in the chart/table need to be proved though by both the LiON and Flow batteries as they have not been in production as long as lead acid. I would think the LCOE for both LiON and flow batteries will drop over the next few years as technology continues its’ onward progress.

    • Mike Dill

      10 kWh at a 5kW rate would be a easy comparison probably favoring LiFePO4, but then 100kWh at a 5kW rate would blow the comparisons as the flow storage medium is less expensive than more batteries.

    • Ruben

      The comparison was done by Redflow. Would you really expect anyone except Redflow to win it?

  • Mike Dill

    RedFlow and other flow battery systems can be very useful for getting off-grid. The 5% of the power coming from the grid in the example above can be substituted by more solar and a small fast reacting power source, such as a Li-ion battery.
    With enough storage potential, flow batteries can solve the ‘corner’ case where you have no sun for two or three days. Storage capacity for flow batteries is relatively inexpensive, and keeping a few days of charge sitting around should not be unreasonably expensive.
    Personally, I am looking at a RedFlow system for baseload and seasonal storage. Take the ZBM unit and add another 400 liters of storage medium, or whatever you need for three or four days of electric power. Adding some fast reacting ‘peaking’ power (Li-ion or capacitors) to the mix then gets you off the grid. The only issue right now for me is the upfront cost. Fortunately it will be coming down.

  • Radbug

    This Zn/Br flow cell looks like a game changer. Over 10 years, on the figures above, the amortisation cost is $AU182 per quarter & it looks like falling with further development. You’ll get 11 years at 10kWh per daily cycle with a 100% Depth of Discharge. You just can’t get those numbers out of Li-ion, at least, at present. This will break the cartel’s grip on the urban grid & force a write-down in its value, almost overnight.

  • Richie

    Can the moderator please expel this troll?

  • Radbug

    Let’s do some arithmetic: Powerwall 7.4kWh unit. Costs $AU3,000. At a DoD of 33%, you’re looking at 2.4667kWh of storage (with a 5 year life span). This adds up to $AU150 per quarter. A 20kWh/day family will need 10kWh of storage. Thus, this family will need 10/2.4667, or 4.05, 7.4KWh Powerwall units. This results, over 5 years, in a cost of $AU150 x 4.05 = $AU608.00 per quarter. Contrast this number with Zn/Br’s quarterly cost of $AU182. Game, set & match!

    • Vincent Lopez

      I think the Tesla Powerwall 7kWh is going to cost alot more than $3k, more like AUD $10,000 – $12,000 …