Spacecraft --- Space Shuttle --- Power

Electrical power is needed for all of the on-board systems of the orbiter. And electricity inside the space shuttle is made from three fuel cells. These fuel cells combine oxygen and hydrogen from pressurized tanks in the mid fuselage to make electricity and water.
Like a power grid on Earth, the orbiter has a distribution system to supply electrical power to various instrument bays and areas of the ship. The water is used by the crew and for cooling.

Basic Structure and Launching Position and Orbit Communication Navigation Power Computer Returning to Earth