If they are going to limit themselves to just renewable energy then they will likely loose out on the best price possible in some countries. However this does make sense if you think about it since renewable energies it doesn't make sense to just turn them off when there is excess power however fossil fuel plants this does make a lot of sense. 

The big question for this company is how often they have to move their rigs and what the internet connectivity is like in the new country that they are put in. 

Hopefully they don't have to be right next to the windfarm since there is no guarantee of decent internet connectivity on site.  That would be my only problem that I can see with this project besides the risk of countries trying to ban crypto and thus would likely not want to subsidize mining it.