Northwestern Energy – Timeline of Montana Generation Portfolio

Since 2011, we have added 780 MW of generation, both owned and long-term contract to our generation portfolio, all of which is from carbon-free resources.

Today, our Montana electric portfolio is built on the carbon-free hydro system, along with wind, coal, gas
and solar. NorthWestern’s electricity portfolio has the capacity to be 70% carbon free. However, because wind and solar don’t always produce to their full capacity, our actual generation is about 61% carbon free.

Our portfolio produces enough energy to meet customers’ average energy demand. However, at times
of high-energy demand – the coldest nights in winter and the hottest days of summer – our customers’ needs exceed our generation and customers are at risk both of insufficient energy supply and of volatile prices on the regional energy market. We call this market price risk.