Montana Gov. Brian Schweitzer and Saskatchewan Brad Wall signed a memorandum of understanding Thursday in the rotunda of the Saskatchewan legislative building. (Stefani Langenegger/CBC)

The leaders of Saskatchewan and Montana have signed an agreement on a $270-million plan to capture and store carbon dioxide, but there's still a big question mark over where most of the money will come from.

Premier Brad Wall signed a memorandum of understanding with Montana Gov. Brian Schweitzer on Thursday in Regina.

What's planned is a carbon capture and sequestration project, in which CO2 gas would be captured from one of Saskatchewan's coal-fired power stations, then piped to eastern Montana where it would be injected deep into the ground.

If the money is found, construction on the plant could begin as early as this fall, and it could be operational as early as summer 2011, the Saskatchewan government said in a news release.

So far, the Saskatchewan government has said it would spend up to $60 million.

Wall and Schweitzer will each apply for $100 million from their respective federal governments.

Over four years, the goal is to capture up to one million tonnes of CO2, a greenhouse gas that contributes to global warming.