Underutilization of oil shale as an energy source

The industrial process needed to extract the oil demands hot water, making it much more expensive and less energy-efficient than conventional oil. The mining operation is extremely damaging to the environment. As of 1997 no oil from oil shale is being produced anywhere in the world. A variety of processes have been tried. All have failed to be economically viable.
Oil shales are seen as the US government's energy stopgap. They exist in large quantities in ecologically sensitive parts of Colorado, Wyoming and Utah at varying depths. A number of oil companies and the US Bureau of Mines have made substantial efforts but with no commercial results.
Until the conventional oil of the world is largely depleted, oil shale and oil sand deposits are likely to represent only a very small fraction of world production. The production will always be insignificant relative to potential demand.
(F) Fuzzy exceptional problems