The power distribution screen shows how much power is being used by which systems. The yellow lines indicate required power levels to operate. Systems with multiple yellow lines (such as engines) have varying levels of power requirements depending on speed levels. Faster speeds will require more power. Systems grayed out are not currently receiving enough power to function. The idea is to balance which systems are needed, powering down systems that aren't currently being used and giving more power to those that need it. Power levels can be altered by dragging the mouse over the end of the green bar to pull it one direction or another. Total power used, the power draw, and the available power are all listed here. Batteries or a power reactor provide power to the ship.