Premier Rachel Notley says Alberta's new carbon tax could provide the missing funding for the planned Green Line of Calgary's LRT system, a megaproject expected to cost $4.5 billion.

So far, there is a $1.5-billion pledge from the federal government toward the project and the city has devoted $1.5 billion of its own, but the provincial government has yet to specify how — or even if — it will pony up the remaining $1.5 billion.

In a year-end interview, Notley said she wants to make an "evidence-based decision" on how to spend $4.4 billion in uncommitted capital funds on infrastructure projects across Alberta, but noted that's not the only avenue for funding that may be available for the Green Line.

"There's also the potential for a case to be made for this through our climate-change plan," Notley said.

Alberta's planned tax on all carbon emissions — set to begin at $20 per tonne in January 2017 and increase to $30 per tonne in January 2018 — is expected to generate billions of dollars annually and Notley said much of that money will be used to make "make energy-efficiency investments."

"And we've always seen a growth of public transit as part of those energy-efficiency opportunities," the premier added.

The Green Line is a new leg of Calgary's light-rail transit system that would run from the city's northern periphery, though downtown and all the way to the deep southeast.

Rachel Notley

Premier Rachel Notley speaks with Rob Brown during a year-end interview with CBC News Calgary. (CBC)

Once complete, it is expected to serve hundreds of thousands of commuters daily.

"The Green Line is not only going to move commuters who are stuck out in the deep suburbs, it's also going to build vibrant neighbourhoods at every stop along the line and provide a habitat for Calgary's next million Calgarians," Coun. Gian-Carlo Carra said of the project.

Calgary's LRT system has run entirely on electricity generated through renewable sources since 2001.

WATCH Part 2 of Rob Brown's interview with Rachel Notley here:

Alberta Premier Rachel Notley chats with CBC's Rob Brown - Part 2 of 25:32