Isomers for energy storage
Isomer Energy Storage BTG developed nuclear isomers as energy-storage/energy-delivery systems for defense and civilian applications. Nuclear isomers are long-lived (> 1 ns) excited states of nuclei that release their excess energy by electromagnetic decay. The nuclear state energy densities stored in some isomers are 10^3 to 10^4 times higher per unit mass (~10^9 J/g) than for chemical systems. This leads directly to the possible application on isomers as batteries to provide useful energy in space or battlefield operations or as flash discharge devices to provide an intense pulse of penetrating electromagnetic radiation. The utility of isomers for energy storage depends on their half-life (T1/2 ~ 1 year or greater) and net energy gain, and on the ability both to produce them and to stimulate the release of their stored energy. BTG investigated novel methods that could provide > 10^16 nuclei of the isomer 178m^2-Hf in a highly concentrated form for future triggering studies, and the methods to produce and trigger other isomers that are candidates for high density energy storage. Innovative triggering concepts using both neutrons and fast-pulsed x-ray sources were studied both theoretically and experimentally.
Energy storage through isomer reactions