For making small amounts of electricity without building a dam, the small-scale hydroelectric generator is often the best solution, especially where fast-flowing streams on steep slopes are close by. A small-scale hydro system usually consists of an enclosed water wheel or turbine, which is made to spin by jets of high-velocity water. The water is taken from the stream and moved down slope to the turbine through a long pipe called a penstock. Water flowing through the penstock picks up speed, and is directed at the blades of the turbine by nozzles. The turbine spins continuously, as long as there is water to drive it. The turbine is connected to an electrical generator, and the electricity is then available for running appliances or charging batteries. The spent water is returned to the stream. This kind of system is called a "micro-hydro" system, "run-of-stream hydro" or "low-impact hydro."