What are nonrenewable energy sources?

Nonrenewable energy sources are defined as energy sources that cannot be replenished within a human lifespan. This includes fossil fuels like coal, oil, and natural gas, which take millions of years to form and are therefore finite in supply. Once these resources are extracted and used, they cannot be replaced quickly, leading to depletion over time. This is in contrast to renewable energy sources, which can be replaced naturally in a relatively short period, such as through natural processes that occur on a human timescale.

In short, nonrenewable energy sources are characterized by their limited availability and the long timeframes required for their formation, making them a key concern in discussions about sustainable energy use and environmental impact.