Nonrenewable resources such as minerals and fossil fuels cannot be replaced at the same rate at which they are consumed. They are finite resources formed over long geological periods. Renewable resources such as solar, wind, and hydropower can be replenished naturally in a short period of time through natural processes like the sun's heat and the wind. The key difference between nonrenewable and renewable resources is that nonrenewables are depleted once extracted while renewables can be replenished within our lifetimes through natural cycles.