US energy secretary Steven Chu hasn’t ruled out the use of tar sands as an energy source, which has delighted Canadian oil producers.

Chu’s comments came at a Reuters energy summit . His message was that the tar sands issue (see here for some background, subscription required) is complicated, but hinted that he thinks technological advances might help to bring down the energy costs for extracting oil from the tar sands.

“It’s a complicated issue, because certainly Canada is a close and trusted neighbor and the oil from Canada has all sorts of good things. But there is this environmental concern, so I think we’re going to have to work our way through that," Chu said. “But I’m a big believer in technology.”