All the prison buildings and services will consume a certain amount of energy and water units. You can see the power and water counter at the top of your playing screen. 
Pay attention to the new objects, services, and building dialog windows to find how many units of power or water they would need to work. If your game states that there is not enough energy or water, tap on the counters or explore the map to find the electricity room and the water pump station.

If you run out of energy or water and don't find these areas on the map, you can tap on the "+" symbol. The game will take you directly there!

If you have these items at max at STILL need more energy, it means you need to upgrade the objects you already have so they consume less energy and you can use the rest in new ones.