Another idea is what Liberal environment critic David McGuinty calls a "location-efficient mortgage" that would let people who buy homes near public transit borrow mortgage money at a lower interest rate. That would encourage transit use and discourage driving.
An American idea, notably West-Coasty, that's been around for a decade or so.
Good in that it encourages city living and increases in urban density. Bad in that it doesn't offer much to anyone outside of those ridings already inclined to vote Liberal.
The broader concept of a "green mortgage" discussed in the piece is solid, if small-bore and unflashy (I don't know that you can hang your whole environmental platform on it). One advantage is that it can be marketed as being good for the environment generally, without reference to particular issues like AGW.