The waste from hundreds of thousands of hogs will soon be powering vehicle diesel engines if Smithfield Farms follows through on a plan announced Friday. Smithfield, the world’s largest hog producer, intends to build a $20 million waste-to-energy facility in southwestern Utah that will convert swine manure into biodiesel fuel, which burns more cleanly than standard diesel. Smithfield currently runs a huge hog farming operation in Utah, where 1 million hogs are raised and slaughtered each year and 500,000 pounds of solid hog doo-doo are produced each day (yes, we said each day — egads!). Currently the hog waste is stored in huge open pits, and the Utah farm has been fined $45,000 over the last seven years for leakage from the pits. Smithfield, which has a long and dirty record of hog-waste pollution problems, is looking to build a second waste-to-energy plant in a southwestern state.