Energy is the source of power for mines. Energy is provided by the Solar Array, Nuclear Power Plant, Genesis Solar Satellite and Helios Solar Satellite. Unlike ore, crystal or hydrogen, energy is persistent and cannot be stored and spent at a later time. Energy becomes "insufficient" if the mines or synthesizer on a planet are upgraded beyond the energy production capabilities of that planet. Because mines require energy to run, insufficient energy causes resource production to be less than capacity. When mines show the large "Insufficient Energy" notice in place of the building picture, they are running at less than capacity. To select which mines receive energy preference, use the CAPACITY dropdown menus on the Buildings page, reducing the percent of the mines whose output you need less.