Canadian pipeline company TransCanada defended its proposed Keystone XL pipeline against critics who charge the project\'s risk is underestimated. TransCanada is proposing an extension of its Keystone pipeline carrying crude from Alberta oil sands projects to U.S. markets. Environmental groups allege that type of oil is more dangerous than conventional crude. TransCanada spokesman Terry Cunha told the Calgary Herald allegations included in a study published by advocacy group Friends of Earth are wrong. \"We would not put our reputation or the public at risk by doing the things that this document, released by the Friends of the Earth, suggests,\" he said. A study from the University of Nebraska, published by the advocacy group Monday, concluded TransCanada made \"flawed and inappropriate assumptions\" about the expected spills from its pipelines. The report said it estimated that 100 spills were likely over the 50-year lifespan for the proposed Keystone extension. TransCanada said it expected 11. The existing line has reported 16 spills from pumping stations since launching one year ago. The extension would reach from Oklahoma to refineries along the Gulf of Mexico. Canadian officials say the regional economy would suffer without the project.