A generalized diagram of an in-situ retorting plant for extracting oil from oil shale. In-situ retorting entails heating oil shale in place, extracting the liquid from the ground, and transporting it to an upgrading or refining facility. Because in-situ retorting does not involve mining or above ground spent shale disposal, it offers an alternative that does not permanently modify land surface topography and that may be significantly less damaging to the environment. Billions were spent in the