> Renewables are used differently, in that there's a lot less ability to rely on them to generate power.

I am confused on your reasoning here.

Solar energy covers the daylight hours. Wind power covers the evening / night time hours.

Storage technologies smooth out the bumps.

Nuclear plants tend to experience long down times for maintenance - which hardly makes them 'reliable'.

Xcel is based in a part of the country with easy access to wind energy. I suspect that that calculation is playing a much larger role than you are considering. Specifically, if Xcel can site wind farms close to the customer, there can be a significant savings in power loss due to transmission.

Windfarms can be built in smaller units of generation power and built in the airspace over farms. (This is why conservative Kansas really like renewables - farmers see them as a backup source of revenue.)