I think the greatest invention is the type of machine that creates electricity from renewable resources. For example: water turbines, wind turbines, and S.P.P panels (solar powered photovoltaic panels.)
Hydroelectric power (or more commonly known as hydropower) - On a lake or a river there is usually a dam. Have you ever wondered what is inside? Inside a dam there are water turbines. The water exiting the dam turns the turbines, the turbines then create electricity.
Wind turbines operate on a single principle. The wind turns the huge propellers, which then start the turbine. The wind turbine is connected to the base, and starts to create energy.
S.P.P panels, also known as solar powered photovoltaic panels, convert the sun’s rays into electricity. These panels create electricity by exciting the electrons in silicone cells using the protons of light from the sun. The panels can supply energy to your house or job.
In conclusion, the renewable power creators are a way to sustain our Earth - water turbines, wind turbines, and S.P.P panels. Burning oil or coal cause global warming, which is bad for our environment.