PUEBLO, Colo. (AP) -- Generating capacity at Xcel Energy's $1.3 billion coal-fired Comanche Power Station is improving following a rocky start.

The Denver Post reports Sunday that the plant ran at an average of only 52 percent last year in its first full year of operation. During the first nine months of 2012, the plant has operated at 71 percent capacity.

The plant had been scheduled to begin operations in September 2009 but has been hampered by needed repairs and modifications to fix leaking steam tubes in the boiler and muffle a high pitch whine from an induction fan that could be heard as far as 3 miles away.

The company estimates paying for the new plant will add $3.73 a month to average residential energy bill.