Oil shale holds trillions of barrels, yet almost nobody can profit from it
A 2016 estimate put the world's oil shale resources at the equivalent of 6.05 trillion barrels, several times global proven oil reserves. Yet only Estonia and China run well-established industries. The catch is that the rock contains no oil yet, just kerogen that must be cooked out at great cost.
Oil shale is a fine-grained sedimentary rock rich in kerogen, a solid mix of organic compounds formed from algae, spores, pollen and plant debris that heat and pressure have not yet turned into petroleum. It is not strictly a geological category; petrologist Adrian Hutton called it an economic term, and not every oil shale is technically shale. It also differs from oil-bearing shales such as the Bakken Formation, whose tight oil is confusingly also called shale oil. Germany's fossil-rich Messel Pit, a UNESCO World Heritage Site, is an oil shale deposit.
Using it means either burning the rock directly as a low-grade fuel or heating it until pyrolysis releases a vapour that condenses into shale oil and a combustible gas. That costs more than pumping crude and brings environmental worries over land use, waste, water, air pollution and greenhouse emissions. More than 80 percent of known resources lie in the United States, mostly in the Green River Formation across Colorado, Utah and Wyoming.
People have exploited it for millennia. Around 3000 BC Mesopotamians used 'rock oil' for roads and adhesives, and Iron Age Britons carved and polished it into burial cists and ornaments. In 1694 an English patent went to three men who found a way to make pitch, tar and oil from a kind of stone. Industrial mining began at Autun, France, in 1837, and Scottish oil shale fed the Industrial Revolution's hunger for lamp oil and paraffin, peaking around 1913 with 120 works.
The industry has boomed and busted. Cheap petroleum killed most projects after the Second World War; world output peaked at 46 million tonnes in 1980 after the oil crisis, then slumped. On 2 May 1982, remembered as Black Sunday, Exxon cancelled its 5 billion dollar Colony project in Colorado, putting more than 2,000 people out of work. A revival began in the early 2000s.
Source: Oil shale
