Renewable / non-renewable

Renewable Energy Resources are ones that won't run out.
Example: Winds will keep on blowing, whether we use the energy or not. So Wind power is a renewable energy resource.
Non-renewable sources will eventually run out. Example: When we've extracted all the Earth's oil, there isn't any more. So oil is NOT a renewable energy resource.
As we realise more and more that fossil fuels are going to run out, we're trying harder to develop other means of generating the electricity on which we depend. Renewable sources, such as solar, hydro-electric, tidal and wind power are particularly attractive, although they do have drawbacks.