China’s used cooking oil is starting to clean up dirty US diesel

China’s used cooking oil is starting to help US trucks run cleaner — and that’s even after it has traveled halfway around the world.

Makers of renewable diesel in the US imported about 530,000 barrels of used cooking oil from China in January and February, and they’re expected to bring in 239,000 barrels next month, according to analytics firm Kpler. The shipments are the first US imports of the oil in the firm’s data dating back to 2017.  

The trade underscores a push by North American refiners to profit from government subsidies aimed at preventing catastrophic climate change. It also highlights the potential for renewable diesel — which is chemically identical to petroleum diesel but cuts greenhouse-gas pollution by as much as 80% — to reduce emissions from the fuel that powers America’s heavy vehicles and machinery.

Shipping a standard mid-range tanker of used cooking oil from China to the US Gulf Coast emits around 6,000 tons of greenhouse gases, but burning that cargo’s worth of renewable diesel can save 100,000 tons of emissions over regular diesel, according to data from BloombergNEF. Saving that much emissions would require 1.65 million tree seedlings to grow for 10 years, based on data from the Environmental Protection Agency.

Used cooking oil and waste animal fats also are reaching the US from as far away as New Zealand and Australia to be processed into substitutes for petroleum diesel and jet fuel. The climate benefits have spurred US biofuel mandates and other regional incentives that make the green fuels competitive on costs. 

Under the US program alone, one gallon of renewable diesel generates credits of around $3.83 in the current market, according to BloombergNEF. A whole cargo is equivalent to $37.8 million of credits.

California offers additional incentives under a state program that accounts for the lifecycle emissions of a fuel, including those from the transportation of its feedstock. The state incentives add up to an additional 84 cents in credits for a gallon of feedstocks turned into renewable diesel. Combined with the federal incentives, that would boost the total credits generated by a whole cargo to $46 million in today’s market, according to data from BloombergNEF and Argus Media.

The calculations — which make up the carbon intensity score of a fuel — mean renewable diesel made from used cooking oil collected from California restaurants would generate more credits than if it were produced from Chinese waste oil.