Flow Battery Stores Wind And Solar Energy
April 24, 2013

New Battery Could Be Key To Wind Energy

Lee Rannals for redOrbit.com — Your Universe Online

Researchers reported in the journal Energy & Environmental Science they have designed a low-cost, long-life battery that could be used in solar and wind energy.

Electrical grids are unable to tolerate large and sudden power fluctuations caused by intermittent sunlight and wind. The team saw the need for energy storage systems to help smooth out the peaks and valleys of this intermittent power.

Researchers from the US Department of Energy´s (DOE) SLAC National Accelerator Laboratory and Stanford University developed a new "flow" battery that is less expensive and a better solution than what is currently available.

Flow batteries available today pump two different liquids through an interaction chamber where dissolved molecules undergo chemical reactions that store or give up energy. The chambers contain a membrane that only allows ions not involved in reactions to pass between the liquids while keeping the active ions physically separated. The major drawbacks from this design include the high cost of liquids containing rare materials and the membrane.

The new battery design uses only one stream of molecules and does not need a membrane at all. Its molecules consist of the relatively inexpensive elements lithium and sulfur, and the entire molecular stream is dissolved in an organic solvent. The team created a miniature system using simple glassware to demonstrate their concept.

[ Watch the Video: Lithium-Polysulfide Flow Battery Demonstration ]

"In initial lab tests, the new battery also retained excellent energy-storage performance through more than 2,000 charges and discharges, equivalent to more than 5.5 years of daily cycles," said Yi Cui, a Stanford associate professor of materials science and engineering and a member of the Stanford Institute for Materials and Energy Sciences, a SLAC/Stanford joint institute. "We believe our new battery may be the best yet designed to regulate the natural fluctuations of these alternative energies."

The team plans to make a laboratory-scale system to optimize the battery's energy storage process and identify potential engineering issues.

"For solar and wind power to be used in a significant way, we need a battery made of economical materials that are easy to scale and still efficient," Cui said.

Another Stanford team said back in March it had begun to figure out what grid-scale battery technologies would do to the carbon footprint. The researchers said grid storage is energetically expensive, and some technologies will require more energy to build and maintain than others.

“Wind and solar power show great potential as low-carbon sources of electricity, but they depend on the weather,” said co-author Sally Benson, a research professor of energy resource engineering at Stanford and the director of GCEP. “As the percentage of electricity from these sources increases, grid operators will need energy storage to help balance supply with demand. To our knowledge, this study is the first to actually quantify the energetic costs of grid-scale storage over time.”