Hydro-electricity is a renewable resource. This is because it is generated from the energy of moving water, which is constantly replenished by rainfall and the water cycle. The water flows through a turbine to generate electricity, and the process can be repeated indefinitely as long as there is water flowing through the system.
On the other hand, petroleum, coal, natural gas, and peat are all non-renewable resources. They are formed over millions of years from the remains of dead plants and animals, and once they are extracted and burned, they cannot be replaced. As a result, they will eventually run out and are not sustainable in the long term.