The world’s supply of fossil fuels is technically limited because the natural processes to create them take millions of years, much more slowly than the rate at which we are drawing those fuels out of the ground. Hence why they are not considered “renewable” fuels. However, since the dawn of the fossil fuel age in the 1800s, we have found again and again that we have more and more recoverable resources than we ever dreamed of. 20 years ago, a time when “peak oil” theories were coming into vogue due to declining domestic production, the Energy Information Administration (EIA) reported 21 billion barrels of proved oil reserves and 164 trillion cubic feet of proved natural gas reserves. As of 2017, these numbers increased to 39 billion barrels of oil and 438 trillion cubic feet of natural gas, a complete reversal of the gloomy picture of declining reserves from prior decades .
Looking at the changes in reserves in regions of the U.S. where the shale revolution has taken hold tells an even more compelling story. The EIA set the amount of proved reserves in the Permian Basin at 13 billion barrels as of 2016, compared to 4.5 billion barrels in 1998 , and the U.S. Geological Survey estimates that the Wolfcamp shale alone contains 20 billion barrels of undiscovered, recoverable oil . The increase in natural gas reserves in the region of the Marcellus shale, which lies across Ohio, Pennsylvania, and West Virginia, has been even more dramatic, from 5.5 trillion cubic feet in 1998 to 148 trillion cubic feet in 2017 . Thanks to the shale revolution, the amount of proved reserves of oil and gas has been growing rapidly in recent years and will likely continue to grow for a long time.
As technological advances replenish and increase our proved reserves, i.e. what is recoverable under existing economic and operating conditions, our total estimated reserves also continue to grow as new fossil fuel resources are discovered. The latest estimates show that the U.S. has at least 310 billion barrels of recoverable oil, enough for almost 80 years of production at current rates . 50 billion barrels were added to this total in just the past year. North America has over 2 quadrillion cubic feet of recoverable natural gas, the most of any region in the world and enough for more than 60 years at current production rates . In addition, the U.S. has long been known to have the largest coal reserves in the world. Current estimates show that the lower 48 states have enough recoverable coal to meet current domestic demand for 350 years . Finally, the U.S. can do even more by opening up more federal lands to energy development. For example, the largest known deposits of oil shale in the world, with roughly 4.2 trillion barrels of oil in place, primarily lie on federal lands in Colorado, Wyoming, and Utah , but the federal government has been reluctant to lease this land even for research purposes, much less actual development.
Energy demand and production will always have their booms and busts due to economic cycles and price fluctuations, but the fact that more than 80% of the energy we consume comes from petroleum, natural gas, and coal  will not change in the foreseeable future. And thanks to the shale revolution, domestic production is rising to satisfy that continued demand. The EIA projects that the U.S. will produce oil and natural gas at record levels in 2018 and again in 2019 and will become a net energy exporter within the next 5 years . History has proven that human ingenuity working within a free market system has an incredible ability to solve technical challenges and find more energy resources. As long as we maintain policies and support market systems that allow human innovation to flourish, our ability to find and access more energy is truly unlimited.
 EIA (Energy Information Administration). 28 November 2018. “Proved Oil Reserves as of 12/31.” Accessed 5 June 2019.
 EIA (Energy Information Administration). 28 November 2018. “Natural Gas Dry, Proved Reserves as of Dec. 31.” Accessed 5 June 2019.
 U.S. Geological Survey. November 2016. “Assessment of Undiscovered Continuous Oil Resources in the Wolfcamp Shale of the Midland Basin, Permian Basin Province, Texas, 2016.”
 Rystad Energy. 15 June 2018. “The U.S. Again Holds More Recoverable Oil Than Saudi Arabia.” Accessed 12 September 2018.
 Rystad Energy. August 2018. “North America to Drive Global Gas Production Growth.” Accessed 12 September 2018.
 EIA (Energy Information Administration). 15 November 2017. “Annual Coal Report 2016.”
 U.S. Geological Survey. 16 December 2016. “Overview: Oil Shale.” Accessed 14 September 2018.
 EIA (Energy Information Administration). 6 February 2018. “Annual Energy Outlook 2018.”