Non-renewable energy refers to energy sources that cannot be replenished in a short time frame. These sources, such as coal, oil, and natural gas, are formed over millions of years from the remains of ancient plants and animals. Once extracted and used, they are depleted and cannot be replaced quickly, leading to concerns about sustainability. The use of non-renewable energy contributes to environmental issues, including air pollution and climate change. As these resources are burned for energy, they release greenhouse gases, which trap heat in the atmosphere. This has prompted a shift towards more sustainable energy sources, like solar and wind energy.