A Polyoxometalate Flow Battery

Abstract: A redox flow battery utilizing two, three-electron polyoxometalate redox couples was investigated for use in stationary storage in either aqueous or non-aqueous conditions. The aqueous battery had coulombic efficiencies greater than 95% with relatively low capacity fading over 100 cycles. Infrared studies showed there was no decomposition of the compound under these conditions. The non-aqueous analog had a higher operating voltage but at the expense of coulombic efficiency. The spontaneous formation of these clusters by self-assembly facilitates recovery of the battery after being subjected to reversed polarity. Polyoxometalates offer a new approach to stationary storage materials because they are capable of undergoing multielectron reactions and are stable over a wide range of pH values and temperatures.

Damping of Inter-area Oscillations using Energy Storage

Abstract: Low frequency inter-area oscillations have been identified as a significant problem in utility systems due to the potential for system damage and the resulting restrictions on power transmission over select lines. Previous research has identified real power injection by energy storage based damping control nodes as a promising approach to mitigate inter-area oscillations. In this paper, a candidate energy storage system based on UltraCapacitor technology is evaluated for damping control applications in theWestern Electric Coordinating Council (WECC), and an analytical method for ensuring proper stability margins is also presented for inclusion in a future supervisory control algorithm. Dynamic simulations of the WECC were performed to validate the expected system performance. Finally, the Nyquist stability criteria was employed to derive safe operating regions in the gain, time delay space for a simple two-area system to provide guaranteed margins of stability.

Experimental Deformation of Salt in Cyclic Loading, Insights from Acoustic Emission Measurements

Abstract: Compressed air energy storage (CAES) in geologic media has been proposed to help ensure reliability of renewable energy sources, for example wind and solar, by providing a means to store energy when excess energy was available, and to provide an energy source during non productive renewable energy time periods. Such a storage media may experience hourly (perhaps small) pressure swings within a geologic storage media. This implies that the storage "container," for example, a salt cavern, may experience small irregular pressure cycling.