The energy we use on Earth comes from a small number of sources. The non-renewable sources are the fossil fuels (coal, oil and natural gas) and nuclear fuel such as uranium. They took millions of years to form or are mined in limited amounts, so they will run out and cannot be replaced within a human lifetime.
The renewable sources are biofuel, wind, hydroelectricity, the tides and the Sun. These are naturally replaced, so they do not run out. Biofuel is made from plants or waste, and the plants can be regrown.
The sources are used in different ways. In most power stations a fuel (fossil, nuclear or biofuel) heats water to make steam, and the steam turns a turbine connected to a generator. Wind turns a turbine directly with moving air, and falling water and tides turn turbines in the same way. Solar cells transfer light from the Sun straight into electricity. Petrol and diesel, made from oil, are fuels for transport, and natural gas is widely used for heating homes.