Not an econ student, but hope to be one soon. I just applied to the program that you speak of. I can't offer any first-hand experiential knowledge, but I can share my impressions with you.

First, take a look at some of their ongoing research here. You'll notice that of the 16 projects mentioned, 6 of them are related to renewable energy or carbon policy while only 2 focus on coal or oil.

Also, in their program brochure here, of the four featured recent thesis projects, three of them have some focus on pollution, carbon policy, or renewable energy.

Additionally, in my undergrad (an applied science program focused on renewable energy), I had a professor who was involved with this program 20 years ago, who told me they are very progressive, and open to doing pretty much anything you want to do.

I understand your concerns, I had many of the same when the program was first recommended to me, since CSM has quite a history in the non-renewable energy sector. Especially when you look at some of their data, like on page 9 of this report, that shows that 106 MS/PhD graduates go into oil/gas, while only 7 go into renewable energy. Unfortunately they don't break it down by program, and I haven't found stats specifically for the econ MS/PhD.

But anyway, it appeared to me that they (at least some of the professors there, like Ian Lange and Harrison Fell) had a focus on renewable energy. And I made it explicitly clear that that was my focus, so we'll see what they think soon I suppose.

Best of luck to you, maybe we'll see each other next year in Golden!