What is an example of a non-renewable energy source?

Coal is an example of a non-renewable energy source because it is a fossil fuel formed from ancient plant materials over millions of years. Once extracted and consumed for energy, coal cannot be replenished on a human timescale, meaning that its reserves will eventually deplete. This characteristic distinguishes non-renewable resources from renewable ones, such as solar, wind, and hydroelectric power, which are naturally replenished in a relatively short period and can be used sustainably. As fossil fuels like coal are burned for energy, they also emit greenhouse gases, contributing to environmental concerns such as climate change.