Back in his shed, he opens a few of the dozens of blue barrels in storage. Sometimes the content is liquid, then it is again a thick solidified mass. Some prawn crackers are still floating in one barrel, but that’s no problem for Chris. “All this grease is heated and then the moisture and dirt sinks down.” This process is repeated until the oil is completely clean again. The clean oil is used for biodiesel. “Completely recycled”, says Chris.