Unocal Oil Shale Plant, Colorado

Unocal operated this $650 million oil shale plant from 1985 to 1991, and it has sat idle for most of the following decade. Oil shale was considered a significant source of energy into the 1980's, and geologic formations under western Colorado and eastern Utah were determined to be the richest regions for this resource, estimated (according to a state publication released in 1980) to contain 562 billion barrels of recoverable oil, 65% of the world's proven crude oil reserves at the time (!). With projections like this, most major oil companies established leases in the region, and researched recovery techniques. Unocal's plant was the largest and most evolved of these facilities. The plant produced some 4.6 million barrels of synthetic crude oil during its five years of operation, crushing and heating millions of tons of rock in the process (the rock generally yields less than 40 gallons per ton). However, extracting the "oil" from oil shale proved to be too expensive an endeavor, and the industry largely collapsed until its renaissance in the late 2000s. The abandoned Unocal plant has been taken over by a company that uses its massive tanks and heating systems to make baking soda from a nearby underground deposit of nahcolite.