3. Oil shales
These 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, but 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. Shell, Exxon and other oil companies are investing billions of dollars in this expensive oil production method.
RSS