Comments on: Radical New Flow Battery: Look Ma, No Membrane! http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/ Clean Tech News & Views: Solar Energy News. Wind Energy News. EV News. & More. Mon, 29 Dec 2014 04:36:00 +0000 hourly 1 http://wordpress.org/?v=4.0.1 By: Brian Setzler http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-178775 Tue, 27 Aug 2013 16:18:00 +0000 http://cleantechnica.com/?p=55130#comment-178775 While it’s not a simple unit conversion to go from watts/cm2 to $/kWh, the power density is a significant driver of cost. If you double the power density, the stack size is cut in half, so you need half of the electrode material, half of the gaskets, half of the current collectors — basically everything except the tanks and electrolyte. 0.8 W/cm2 is a very good power density. Now I am still a little bit skeptical of membraneless designs because I don’t see how to achieve very high Coulombic efficiencies, but hopefully I’ll be proven wrong. Also, I don’t like that their round trip voltage efficiency was calculated using two different electrolytes. I’d probably subtract a few percentage points from their number.

]]> By: John http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-177267 Mon, 19 Aug 2013 09:37:00 +0000 http://cleantechnica.com/?p=55130#comment-177267 Good question – my understanding is that H2 must be consumed during discharge (H2 + Br2 => 2HBr + energy). Therefore this system will struggle to achieve a competitive cost per kWh for long-term energy storage due to the current high cost of H2 storage tanks/methods (which also limits the competitiveness of traditional H2 fuel cells in the long-term application). However for short-term usage (e.g. a few hours) this is less of an issue (smaller tanks) and it appears that this technology could deliver a very competitive cost per kW (power) for grid balancing. There appear to be some advantages over H2-O2 fuel cells (such as better round-trip efficiency, higher current density and cell potential) which additionally help to deliver a more cost-effective system. However for off-grid applications a system which utilises only liquid reactants would be preferable as it would provide a cost-effective capability to store much larger amounts of energy on weekly or even seasonal timescales.

]]> By: mzso http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-177191 Sun, 18 Aug 2013 18:29:00 +0000 http://cleantechnica.com/?p=55130#comment-177191 “0.795 watts of stored energy per square centimeter. That puts the device on track for the golden $100 per kilowatt-hour mark”

Comparing apples and meat are we? 0.795 watts/ cm2 is the power density of the device. It has nothing to do with stored energy. Which you can’t measure in cm2 since the electrodes are fluids with volume.

]]> By: Wayne Williamson http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-177157 Sun, 18 Aug 2013 14:03:00 +0000 http://cleantechnica.com/?p=55130#comment-177157 Where does the hydrogen gas come from? Is it created when charged and consumed when discharged?

]]> By: Ross http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-177149 Sun, 18 Aug 2013 11:21:00 +0000 http://cleantechnica.com/?p=55130#comment-177149 Doesn’t sound like it was in a closed cycle.

]]> By: MorinMoss http://cleantechnica.com/2013/08/17/radical-new-flow-battery-uses-bromine-instead-of-membrane/#comment-177097 Sun, 18 Aug 2013 01:37:00 +0000 http://cleantechnica.com/?p=55130#comment-177097 Palm-sized prototype?? Very, very preliminary. Let us know when there’s a unit that can power a house reliably for a year.

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