On Tuesday, North Korea finally agreed to shut down its main Yongbyon nuclear facility in exchange for energy aid—a shipment of 50,000 tons of heavy fuel oil, with more to follow. Just what does one do with 50,000 tons of heavy fuel oil?
Not very much. Heavy fuel oil is the cheapest grade of fuel oil available—the thick, viscous sludge left behind at the end of the refining process. After it comes out of the ground, crude oil is heated to over 600 degrees and pumped into a distillation column, where gasoline, diesel fuel, kerosene, lubricants, and other petroleum products are separated out. (This includes light fuel oils—like the heating oil you might have in your basement.) Heavy fuel oil is the dense carbon residue—high in sulfur and other impurities—that remains after all these other distillates have been cooked off.
Also known as No. 6 Fuel oil, Residual Oil, Bunker C, or simply HFO, heavy fuel oil is so thick—roughly the consistency of tar—that it must be heated to around 100 degrees Fahrenheit before it can flow through pipes or be fed into a combustion chamber. Since this process typically requires heavy pressurized steam equipment, the use of heavy fuel oil is practical only on a large scale; for example, in thermal power generators, heating plants, or the large boilers onboard ships.
That's why the United States prefers to give energy aid in this form to recidivist nations like North Korea. The fuel has no uses other than creating power and heat, and it can't be further refined for military use. (You'll never turn heavy fuel oil into jet fuel.) On paper, heavy fuel oil does contain a significant amount of energy—149,690 Btu per gallon, as opposed to 139,000 for distilled home-heating oil. But in practice, it delivers only a fraction of this energy because it's so cumbersome to use.
The energy return is even worse for the North Koreans, because their power plants were designed to burn low-sulfur Korean coal rather than high-sulfur heavy fuel oil. The sulfur content leads to the formation of corrosive acids, which further cripple decrepit, Soviet-designed plants—damaging parts that are no longer available. (The State Department guesses that these plants typically operate at around 25 percent efficiency.)
Despite the inferior quality of heavy fuel oil, North Korea has relied on shipments of it for a long time. Under the Agreed Framework of 1994, the United States made yearly deliveries of about 500,000 tons of heavy fuel oil to seven North Korean heating and electricity-generating plants. (Shipments stopped in 2002 when Pyongyang announced that it was developing a nuclear weapons program.) Over that time, North Korea received roughly 2.1 percent of its total energy needs from shipments of heavy fuel oil, relying on its hydroelectric facilities and coal plants for the rest. That means the initial 50,000-ton shipment Kim Jong-il has coming might account for less than a quarter of a percent of his nation's annual energy needs.
Bonus Explainer: How much is all that heavy fuel oil worth? About $13.4 million. Fifty-thousand tons translates to 333,000 barrels, or 13,986,000 gallons. Multiply that by the per-gallon price listed on the New York Mercantile Exchange earlier this week, and you get the number above.
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Explainer thanks Peter Hayes of the Nautilus Institute.
*Correction, Feb. 21, 2006: A photograph of a cargo ship that originally ran with this story was removed after readers pointed out that the caption information provided by Agence France-Presse was inaccurate. The vessel shown was not an oil tanker.