What type of energy sources are considered renewable?

Renewable energy sources are those that are naturally replenished over short time scales and can be used without depleting the Earth's resources. Solar and wind energy are prime examples of renewable sources. Solar energy harnesses sunlight through solar panels, while wind energy captures the kinetic energy from wind through turbines. Both of these sources are sustainable and have minimal environmental impact compared to fossil fuels, as they do not produce greenhouse gas emissions during operation.

In contrast, coal and natural gas are fossil fuels that contribute to pollution and are non-renewable because they are formed over millions of years and can be exhausted. Nuclear energy, while low in emissions, relies on uranium, which is a mined resource and poses long-term waste disposal challenges, thus not fitting the renewable category. Lastly, while biomass can be renewable if sourced sustainably, it still involves combustion which releases CO2. Hence, solar and wind stand out as the clear renewable sources among the choices.