The vanadium flow battery is a promising technology for energy storage at the grid and microgrid levels, but like any other storage device, it has flaws. Low power density, expensive materials, and instability at high temperatures have kept flow batteries on the fringe of the energy storage market. Over the past two years, Imergy Power Systems has made breakthroughs that could bring this technology into the mainstream. I spoke with engineers from Imergy Power Systems, who gave me the lowdown on