If life reaches galactic proportions, technology should be able to access all of the materials resources, and sustainable life will be defined by the available energy.[1] The maximum amount of biomass about any star is then determined by the energy requirements of the biomass and by the luminosity of the star.[2][2] For example, if 1 kg biomass needs 100 Watts, we can calculate the steady-state amounts of biomass that can be sustained by stars with various energy outputs.