Energy sources that cannot be replenished are called?

Energy sources that cannot be replenished are termed nonrenewable energy sources. This classification includes fossil fuels such as coal, oil, and natural gas, which take millions of years to form and are depleted much faster than they can be replaced. Once these resources are extracted and used, they cannot be restored within a human timeframe, leading to concerns about energy security and environmental impact.

In contrast, renewable energy sources are those that can be replenished naturally in a relatively short period of time, such as solar, wind, and hydroelectric energy. Passive energy sources typically refer to systems that make use of natural energy flows without active mechanical systems, often seen in building designs that maximize energy efficiency. Sustainable energy sources prioritize long-term usability without significant environmental harm but can include both renewable and nonrenewable sources depending on their impact on the ecosystem and the ability to regenerate.