 According to Shell, the hydrogenation process is well suited to the very clean bitumen produced at the Muskeg River Mine, and results in the upgrader producing more light crude oil than it inputs in the form of heavy bitumen.It also produces lower levels of sulfur dioxide emissions than the alternative coking method which removes carbon to produce petroleum coke as a by-product.The Scotford Upgrader has its own hydrogen manufacturing unit and produces most of the hydrogen required for the hydrogen-addition process.