Renewable Energy/Sustainable Energy One problem with powering our world with petrol fuels (coal, oil, natural gas) is that these sources of energy are running out. When we burn them, they also pollute the environment. Renewable or sustainable energy refers to energy sources that can last forever – for example, wind power, water power, solar power, or “bio-fuels” produced from plants. Renewable/sustainable energy sources are also generally clean and don’t harm the environment.