On This Green Earth , Cathy Collentine, associate director with the Sierra Club, comes on the show to discuss TC Energy’s recent decision to cancel the construction of the remaining portion of the Keystone XL Pipeline. The highly controversial pipeline would have conveyed tar sands oil from Alberta, Canada to a distribution center in southern Nebraska. Collentine also shares that although the Keystone XL Pipeline is off the table, an even bigger pipeline is in the works.