Petroleum, natural gas, coal and other materials used to produce energy

Reference

Energy industry - Wikipedia, the free encyclopedia
"The energy industry is the totality of all of the industries involved in the production and sale of energy, including fuel extraction, manufacturing, refining and distribution. Modern society consumes large amounts of fuel, and the energy industry is a crucial part of the infrastructure and maintenance of society in almost all countries. ..."
Fuel - Wikipedia, the free encyclopedia
"Fuels are any materials that store potential energy in forms that can be practicably released and used as heat energy. The concept originally applied solely to those materials storing energy in the form of chemical energy that could be released through combustion, but the concept has since been also applied to other sources of heat energy such as nuclear energy (via nuclear fission or nuclear fusion), as well as releases of chemical energy released through non-combustion oxidation (such as in cellular biology or in fuel cells). ..."

Articles

Reports of Peak Oil's Death Are Somewhat Premature, by Kevin Carson, 22 Jul 2013
Examines shale oil and tar sand oil vis-à-vis the state policies that allow extraction to be profitable
"These new sources of oil all have very low energy returns on energy investment. It takes a lot of energy to get just a little more net usable energy at the end of the process. That means it's only profitable when it's heavily subsidized by taxpayers, extracted from stolen land at government expense. And even then, the total increase in net energy output doesn't equal the oil produced by all those legacy fields in places like Saudi Arabia and Texas that are near exhaustion."