This article is by Sarah Chea and read by an artificial voice.
[EXPLAINER]
While U.S. President Donald Trump touts American crude as an alternative for allies facing Iran-linked supply disruptions, the idea can sound fanciful — nowhere more so than in Korea.
On paper, U.S. crude is competitive and lower in sulfur, making it easier to refine. Still, industry insiders agree that U.S. supply cannot fully replace Middle Eastern imports, which account for 70 percent of Korea's total.
The constraint is not about volume; rather, it lies in the structure of Korea's refining system, which is optimized for heavy, viscous crude.
Though a non-oil-producing nation, Korea ranks among the world's top refiners, with total capacity placing it roughly fifth globally. Three of Korea's four refiners — SK Energy, GS Caltex, and S-Oil — operate three of the five largest single-site refineries on Earth.
Why, then, does a country so technologically adept at refining remain unable to make U.S. crude its mainstream feedstock, even amid ample supply?
Q. Why can't U.S. crude become mainstream in Korea?
Several factors are at play, but the decisive constraint lies in Korea's industrial architecture and the hardware that underpins it. Feed U.S. barrels into the system, and then refining efficiency drops sharply.
Korean refiners are designed for heavy, viscous, high-sulfur crude from the Middle East, and firms have poured fortunes into upgrading units to crack such grades into higher-value products like gasoline and diesel. The feedstock is foul-smelling and residue-laden, but once processed, it yields diesel, jet fuel and naphtha, which are the petrochemical backbone.
At major Korean refiners, about 30 percent of refining capacity is dedicated to upgrading processes, roughly twice the global average of 10 to 15 percent. In the case of HD Hyundai Oilbank, that share exceeds 40 percent.
By contrast, U.S. oil is light and sweet, which underperforms in Korea's configuration. Processing isn't impossible, but it reshapes the product slate, such as reducing jet fuel output, and erodes profitability within a system optimized for heavier grades.
"From the 1970s, when refining infrastructure was first built, Middle Eastern crude dominated. The system was engineered accordingly," said researcher Chang Tae-hun of the Korea Energy Economics Institute.
"Also, asphalt, a by-product of heavy crude processing, coincided with Korea's construction boom at the time."
As an export-driven manufacturing economy, Korea consumes far more diesel than gasoline, fueling trucks, ships and heavy machinery that serve as the backbone of livelihood-driven enterprise.
U.S. crude tends to skew toward gasoline yields, while Middle Eastern grades produce relatively more diesel and kerosene.
Q. What about the economics, more broadly?
Distance — and the costs it compounds — remains a decisive handicap.
When using Middle Eastern crude, refining costs are low compared to U.S. oil, pricing can be stabilized through long-term contracts, and transit to Korea takes only some 20 to 23 days.
But the United States sits far outside Korea's natural supply basin; Very large crude carriers often cannot pass narrow canals and must round Africa's Cape of Good Hope, stretching voyages to more than 50 days, over twice as long as Middle Eastern routes.
Freight costs rise, and once marine insurance is factored in, the gap in total landed costs widens further.
"Refining units are highly sensitive, so running the wrong light crude through them means risking corroding costly equipment," said a source at a major refiner in Korea. "While U.S. light crude already carries a freight and logistics disadvantage, if Middle Eastern supply is readily available, it is hard to see any refiner diversifying with ease."
Q. How severe is Korea's dependence on Middle Eastern crude?
Currently, roughly 70 percent of Korea's crude imports come from the Middle East, and of that, 99 percent passes through the Strait of Hormuz.
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