Alberta can simply keep using the Canadian dollar, with no downside.
Claimed by: Commonly stated by Alberta independence advocates
False: False as written according to the settled evidence. How we rate.
Short answer
A country can use another country's currency without permission, as Ecuador and Panama do with the US dollar. What it cannot do unilaterally is get a seat at the central bank, a voice in monetary policy, or a lender of last resort. When Quebec's Parti Quebecois proposed keeping the dollar, even its own leader conceded Canada's monetary policy would simply apply and a Bank of Canada seat was not guaranteed. So the claim that there is no downside is misleading: the trade-offs are real, even if their size is debated.
What the evidence shows
Campaigning in 2014, PQ leader Pauline Marois said a sovereign Quebec would keep the loonie and seek a Bank of Canada seat, but admitted Canadian monetary policy would apply and the seat was not assured.
Economists note that using another country's currency means no sovereign monetary policy, no ability to devalue, and no central bank backstop of your own.