Why is diesel so much more expensive than unleaded?

The statewide average for a gallon of unleaded gas hit a new statewide average record on Friday of $4.11, according to AAA.

Diesel hit a record earlier in the week, on Wednesday it was $5.25 per gallon on average across Texas, according to AAA.

But why the disparity?

The last time a gallon of diesel had a nationwide average that was cheaper than unleaded was for a few weeks in August 2009, according to data kept by the U.S. Department of Energy.

Ever since then, diesel has been more expensive.

“We are exporting diesel right now for the war effort in Ukraine. Heavy crude is no longer coming from Russia. Refining of it is not yet at full summer capacity, and the airline industry is near full capacity,” University of Houston’s Chief Energy Officer, Dr. Ramanan Krishnamoorti said Friday.

Krishnamoorti said that the Airline Energy, which has come roaring back, relies on the same crude to make jet fuel that gasoline and diesel do. But when the demand for jet fuel surges, diesel production can take a hit, and that appears to be what is happening now.

At the Valero on Shepherd at the Katy Freeway, unleaded was advertised for $3.99 vs diesel $5.15.