Three firms unknowingly purchased tainted crude oil from U.S. emergency stockpiles last year, according to internal Energy Department emails and shipping documents reviewed by Reuters.
The purchased oil was tainted with significant amounts of hydrogen sulfide (H2S), a chemical that occurs naturally in oil and natural gas but is usually filtered out before the cargo is moved. High levels of H2S gas are lethal to humans and concentrations in crude oil can corrode containers, pipelines and refinery equipment.
The U.S. maintains the Strategic Petroleum Reserve (SPR) to have oil on hand in case of natural disasters, war or other events that can disrupt the global oil supply. If a large part of the reserve is contaminated with H2S, the emergency supply is significantly less useful because the chemical must be removed before the oil can be further refined or used, according to Rueters.
All three shipments came from the same storage area, an underground salt cavern in Texas. The crude was shipped to Royal Dutch Shell, the Australian bank Macquarie Group and PetroChina International America, an arm of China’s state-owned energy company that trades with the U.S.
The Department of Energy acknowledged that only one of the three shipments contained dangerous amounts of H2S.
The entire Strategic Petroleum Reserve is kept in four underground caverns spread over the Texas and Louisiana Gulf Coasts connected to key ports that handle large shipments of oil. The current reserve totals 665 million barrels, according to Reuters.
H2S is one of the leading causes of gas-related worker deaths and is considered a risk in several industries outside of oil and gas such as mining, tanning and some sectors of manufacturing. The gas can appear naturally in sewers and manure pits and is most dangerous in low, enclosed areas where it collects and settles, according to the Occupational Safety and Health Administration.