Over the last two weeks, the maritime world has watched with horror as a tragedy has unfolded in the East China Sea. A massive Iranian tanker, the Sanchi, collided with a Chinese freighter carrying grain. Damaged and adrift, the tanker caught on fire, burned for more than a week, and sank. All 32 crew members are presumed dead.
Meanwhile, Chinese authorities and environmental groups have been trying to understand the environmental threat posed by the million barrels of hydrocarbons that the tanker was carrying. Because the Sanchi was not carrying crude oil, but rather condensate, a liquid by-product of natural gas and some kinds of oil production. According to Alex Hunt, a technical manager at the London-based International Tanker Owners Pollution Federation, which assists with oil spills across the world, there has never been a condensate spill like this.
“It’s typical for us to attend approximately 20 shipping incidents a year and we’ve been doing this for 50 years,” Hunt says. “There have been other condensate spills, but this is the first condensate spill of this magnitude that we’ve dealt with, which gives you an impression of how rare cases like this are.” A 2016 Canadian environmental risk report on condensates also noted “the small size and low frequency of spills to marine water.”
While it might seem that all oil spills would at least be similar, in this case that is not true. Underground, crude is a liquid you can pump. Condensate, on the other hand, is a gas amid the heat and pressure down there. Bring it up to the surface and it condenses into liquid. This liquid is made of hydrocarbons like crude—and is sometimes classed as a form of it—but contains a different mix of molecules than other crude oils.
That mix is substantially lighter, containing more small, simple molecules and fewer large, complex molecules. This composition—and the composition of any form of petroleum—is highly significant for the refiners who turn raw petroleum products into refined fuels and chemicals that they sell. But, in this case, the properties are salient to the disaster and the environmental aftermath.
In technical terms, condensate is primarily made up of alkanes, which you’ve probably encountered a few of in the past when you’re looking for something to burn: methane, propane, butane, and the octane of high-octane gasoline.