Jan 3 (Reuters) - Mdu Resources Group Inc :
* Montana-Dakota Utilities Co signs agreement to purchase power from wind farm expansion
* Agreement also includes an option for Montana-Dakota to buy project at close of construction.
* Expansion includes 13 to 16 turbines, depending on turbine size selected, and will be constructed by ACE
* MDU Resources Group - expansion of thunder spirit wind will boost combined production at wind farm to approximately 150 megawatts of renewable energy
* MDU Resources Group -signed a 25-year agreement with a subsidiary of Allete Clean Energy to purchase power from a wind farm expansion
* MDU Resources Group - if Montana-Dakota buys project, capital will be incremental to capital expenditure forecast of $1.24 billion for 2017 through 2021 Source text for Eikon: Further company coverage: