Separatism is born of a sense of ethnoracial exceptionalism:

1) we're a genealogically different ethnic group from the rest of the country

2) we're better than the major ethnic group of the rest of the country

Both bits are absolutely essential. I can't recall a single instance of a separatist movement based on purely political differences gaining serious ground, Alberta included.

Why just ethnic? It can also be religious, ideological, or based on some economic interest. The US revolution was a mix of tax revolt and ideology. The British were the same ethnic group as most of the leaders of the revolution.