Future resources

What else may be a source of natural gas?

Methane hydrates are crystalline solids consisting of methane molecules surrounded by a cage of water molecules. They are stable in Arctic areas and in ocean floor sediments at water depths greater than 1,000 feet. Methane hydrates are found throughout the world – including off all U.S. coasts. While good data on methane hydrates is limited, the U.S. Geological Survey conservatively estimates that energy contained in the world’s methane hydrates is twice the energy contained in all known fossil fuels on earth -- twice that in all the world’s estimated natural gas, petroleum and coal combined.

In 2008, the U.S. Geological Survey developed its first-ever resource estimate of technically recoverable natural gas hydrates. The federal agency estimated that there are 85.4 trillion cubic feet of undiscovered technically recoverable gas from natural gas hydrates on the Alaskan North Slope, thought to be the largest known resources of natural gas in the world. Technically recoverable means that these resources are recoverable using existing technology.

The research confirmed the potential for natural gas hydrates to contribute to future supply.

Click here to listen to a podcast interview with USGS scientists at Episode 74 of the USGS CoreCast

The National Research Council reached the same conclusion in its 2010 “Realizing the Energy Potential of Methane Hydrates for the United States,”

The report noted that “the existence of such a large and untapped energy resource has provided a strong global incentive to determine how methane might be produced from methane hydrate safely, economically, and in an environmentally sensible way.”

In announcing the results, the National Research Council noted that “although a number of challenges require attention before commercial production can be realized, no technical challenges have been identified as insurmountable.”

Coal Gasification

The U.S. is estimated to have coal reserves of about 500 billion tons (more than 10,000 Tcf-equivalent), more than one-half of which can be recovered under present technical and economic conditions. While technology has minimized most of the air pollution issues associated with coal, coal combustion still produces substantial amounts of carbon dioxide (CO2) – a major greenhouse gas. Currently, there is much publicly and privately funded research into CO2 sequestration, i.e., injection of gaseous CO2 into old gas wells and other underground storage where it is suppose to remain secure for tens of thousands of years. However, another method of CO2 sequestration is to gasify the coal through a pyrolysis process. The gas can then be converted into a natural gas substitute, and transported through the country’s 1.5 million mile gas line system. Importantly, the excess carbon is converted into a solid (charcoal) – not a gas. The solid can then be easily buried, without concern that, at a future time, it will escape into the atmosphere.