Sustainable energy is energy that is produced by renewable, natural sources that are not considered harmful to future generations. Examples of sustainable energy sources include wind, ocean waves and the sun.
Sustainable, or renewable, energy sources do not run out and self-replenish over time. Wind, for example, provides an energy source when harvested and is always available. Sustainable energy sources are considered more cost effective and more compatible with the environment, as they cause less pollution to produce. In contrast, nonsustainable sources are sources that have a finite supply, pollute and eventually run out. Coal and oil are examples of nonsustainable energy sources.