U.S. President Barack Obama's decision to deny approval to the Keystone XL pipeline has permanently changed the discussion on new energy projects, say environmentalists and analysts. "It's premature to talk about other pipelines yet, but if Alberta and Canada don't introduce proper greenhouse gas regulations for the industry, then it's going to be challenging to make the argument that those projects are in the public interest," says Simon Dyer of the Pembina Institute, a clean-energy think-tank.