Fossil fuels are large deposits underground or under the ocean that are derived from living matter from a long time ago (another geologic time). Fossil fuels produce a significant amount of energy when they are burned. Petroleum, coal and natural gas are examples of fossil fuels. Fossil fuels are the nation’s principal source of energy to create electricity at power plants. The popularity of these fuels is largely due to their low costs. Because fossil fuels are a finite resource and cannot be replenished once they are extracted and burned, they are not considered renewable. When they are burned, fossil fuels release carbon dioxide and other gases that impact our environment. Carbon emissions are considered a contributor to climate change