KNOXVILLE, Tenn. — The Tennessee Valley Authority reported its first quarter net income was up $186 million over the same period last year, officials reported Friday.

The utility reported a total net income of $288 million for the three months ending Dec. 31. It credited increased income to lower expenses.

TVA’s total operating revenues of approximately $2.5 billion for the three months ending Dec. 31 were relatively flat when compared to first quarter last year. Power sales were up about 2 percent for the quarter on more normal weather, as milder weather affected sales during the same period last year.

Even with higher sales volume, fuel and purchased power expenses were down $115 million, or about 14 percent, primarily due to an increase in low-cost hydroelectric production and slightly lower natural gas prices.

“Power consumers in the Tennessee Valley are seeing significant benefits from the investments we’ve made to diversify TVA’s power system,” said TVA Chief Executive Officer Bill Johnson. “More than half of the energy supplied by TVA in the first quarter came from carbon-free sources — nuclear, hydro and other renewables that are helping the power system deliver safe, reliable, and cleaner energy — at a lower cost.

Operating and maintenance expense was $32 million lower for first quarter FY18 compared to FY17.

The decrease was partially due to fewer planned nuclear outage days and lower expenses related to identified efficiencies and staffing changes.