Oil shale is a very significant unconventional form of hydrocarbon that exists in many places around the world. The hydrocarbon content in oil shale is kerogen, a partially decomposed algal material that has not been exposed to high enough pressures and temperatures to convert it into oil.

The U.S. Department of Energy publication “Strategic Significance of Oil Shale Resource,” published in March 2004, states that the worldwide oil shale resource base is estimated to be 2.6 trillion barrels. The vast majority, or about 2 trillion barrels, is located within the United States. The most economically attractive deposits, containing an estimated 1.5 trillion barrels, are found in the Piceance Creek Basin of Colorado, the Uinta Basin of Utah and the Green River and Washakie Basins of Wyoming.

Advantages
The extensive deposits located in the United States offer key advantages. The political risk and uncertainty associated with oil shale development in the United States will be less than many of the alternatives for conventional oil found outside the country. The extent of the resource inside the United States is significant and well defined, which almost eliminates exploration and discovery risk for the resource. Production is already close to the finished product market, and these markets are substantial enough to support development of the industry. Successful development of oil shale can greatly enhance the energy security and economy of the United States for centuries.

Issues
The technology for producing oil shale is in different stages of development. Mining and surface retorting, or heating of mined shale, is currently being accomplished in several locations around the world. However, it has not been economically successful for large scale operations in the U.S. Also, only a limited portion of the resource can be produced by mining. Access and recovery of the majority of oil shale will require development of good in-situ techniques. This technology is in its infancy and will require significant future development.

Development of large scale operations in Colorado, Wyoming or Utah will necessitate addressing a number of social issues. Large scale development will impact the population density of the area, and community infrastructures will have to be developed to accommodate the expected growth. There are also concerns about the ownership and use of water in these areas that will have to be managed.

An oil shale industry will have to address a number of health, safety and environmental concerns, many of which were studied in the 1980s when earlier efforts were made to develop this resource. Most of the health and safety issues are fairly well understood, but a greater emphasis is now being placed on environmental impacts, including oil shale's impact on climate change. Oil shale production may generate substantial amounts of carbon dioxide, the impact of which will have to be mitigated.