Low-cost organic compounds including common fluorenone, a bright yellow powder found in candles, hold promise for storing grid energy, indicates research by scientists at the U.S. Department of Energy’s Pacific Northwest National Laboratory. In lab testing that mimicked real-world conditions, a PNNL battery operated continuously for 120 days. The battery went through 1,111 full cycles of charging and discharging – the equivalent of several years of operation under normal circumstances – and lost less than 3% of its energy capacity. Fluorenone is also used in solar panels, in pharmaceuticals such as drugs to treat malaria, and in candles, to give them a pleasant scent. It’s inexpensive and readily available as a waste product from coal tar and from the manufacture of benzoic acid, a common food additive.