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High-Performance Flow Batteries Could Enable Grid-Level Green Energy Storage

High-Performance Flow Batteries Could Enable Grid-Level Green Energy Storage

By E&T editorial staff, Published Friday, July 26, 2019

A low-cost, high-performance battery chemistry developed by University of Colorado Boulder researchers could one day lead to scalable grid-level storage for wind and solar energy, which in turn could help electrical utilities reduce their dependency on fossil fuels.

The innovation, described in the journal Joule, outlines two aqueous flow batteries, also known as redox flow batteries, which use chromium and organic binding agents to achieve exceptional voltage and high efficiencies. The components are abundant in nature, offering future promise for cost-effective manufacturing.

“We’re excited to report some of highest-performing battery chemistries ever, beyond previous limits,” said Michael Marshak, senior author of the study and an assistant professor in CU Boulder’s Department of Chemistry. “The materials are low-cost, non-toxic and readily available.”

Renewable energy sources provide a growing share of electrical production in the US, but currently lack a large-scale solution for storing harvested energy and re-deploying it to meet demand during periods when the Sun isn’t shining and the wind isn’t blowing.

“There are mismatches between supply and demand on the energy grid during the day,” said Marshak, who is also a fellow in the Renewable and Sustainable Energy Institute (RASEI). “The Sun might meet the grid’s needs in the morning, but demand tends to peak in the late afternoon and continue into the evening after the Sun has set.

“Right now, utility companies have to fill that gap by quickly revving up their coal and natural gas production, just like you’d take a car from zero to sixty.”

Although lithium-ion can provide power for smaller-scale applications, you would need millions of batteries to back up even a small fossil fuel power plant for an hour, Marshak said. While the lithium-ion chemistry is effective, it’s ill-suited to meet the capacity of an entire wind turbine field or solar panel array.

“The basic problem with lithium-ion batteries is that they don’t scale very well,” Marshak said. “The more solid material you add, the more resistance you add and then all of the other components need to increase in tandem. In essence, if you want twice the energy, you need to build twice the batteries and that’s just not cost-effective when you’re talking about this many megawatt hours.”

Flow batteries have been identified as a more promising avenue. Aqueous batteries keep their active ingredients separated in liquid form in large tanks, allowing the system to distribute energy in a managed fashion, similar to the way a petrol tank provides steady fuel combustion to a car’s engine when the accelerator pedal is pushed.

While there are some examples of flow batteries operating consistently for decades, such as in Japan, they have struggled to gain a broad foothold in commercial and municipal operations due in part to their unwieldy size, high operating costs and comparably low voltage.


  1. Storage batteries for power generation electrical energy do not exist despite the related media hype.  Grid quality batteries are widly used.
  2. This is an example, evidence - if you will, note the use of "could" - not available, dreaming stage or R&D as one may put it...  Basically, asking for research funding...
  3. Politicians push for those storage batteries because they are clueless about the technology and the application; regulated utilities do not mind, they just pass the buck - charge the ratepayers for capital investments... 
  4. Reading that since solar and wind are weather dependent, the suppliers will store that electrical energy in storage batteries - (i) those batteries do not exist, and (ii) if ordered 'as is' the cost will be prohibitive. 
  5. Of course, storing renewable energy (like solar for evening use) after it was used during the day is a big fat lie - we cannot eat our cake and have it too...  Any stored energy to back up renewables must come of fossil-fueled generation...


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