The Energy Independence and Security Act, signed into law in December, restricts US government procurement of alternative fuels to those whose lifecycle greenhouse gas emissions are equal to or less than those from conventional petroleum sources.
Canada's oil sands - the biggest proven oil reserve outside Saudi Arabia - are considered unconventional fuels, and producing them emits more greenhouse gas than conventional production.
US rejection o f fuel from oil sands could establish an international precedent, jeopardising the billions of dollars the oil majors have invested.
Nonetheless, Henry Waxman, the chairman of the powerful House oversight committee, is pressing the US government to comply with the legislation. In January he wrote to Robert Gates, US defence secretary, whose department is the US government's biggest single oil consumer, requesting that he identify all defence department projects that might be affected by the law.




