A pipeline that would carry crude oil extracted from Canadian tar sand fields to refineries in Texas has edged a bit closer to approval with the State Department’s release of a draft environmental impact statement this month. It concluded that the project’s construction and operation would have “limited adverse environmental impacts.” TransCanada, the project developer and one of Canada’s largest energy infrastructure companies, is proposing to build the 1,930-mile Keystone XL pipeline from Hardisty, Alberta, to terminals and shipping ports on the Texas Gulf Coast. If constructed, the pipeline could carry up to 900,000 barrels a day at its peak when completed in 2012. In the report, the government cites an increasing demand for crude oil matched with the importance of moving away from “unstable foreign oil supplies” as justification for the project. Environmental groups are crying foul, arguing that the government’s assessment misses the bigger picture by ignoring the increased greenhouse gas emissions associated with fuel derived from tar sands. A 2008 study by the Rand Corporation found that carbon dioxide emissions from the production and use of tar sands oil are about 20 percent higher than those for conventional petroleum. While the Obama administration’s energy policy seeks to reduce the country’s global warming emissions and reduce dependence on foreign oil from places like the Middle East, projects like this one demonstrate how those two goals can sometimes be at odds. To address the conflict, the White House Council on Environmental Quality is currently drafting guidelines on how federal agencies can account for climate impacts in environmental statements like this, but they won’t be final until later this year.