Heavy rainfall brings record year for hydro generation at TVA's 29 dams
While heavy rain in the summer might have ruined lots of cookouts and picnics, for Tennessee electricity customers the cloudsthat brought the rain came with the proverbial silver lining.
Hydroelectric dams have been in overdrive for much of the year, producing cheap energy that has brought down energy bills across the state.
"It has been a wet year, and our river operations team took advantage of it," John McCormick, Tennessee Valley Authority's vice president for river operations, said in a news release. "As our cheapest energy source, all this hydro generation has helped lower our fuel cost to customers."
Through October, total rainfall across the state was 21 percent higher than average, and in the eastern part of the state, where many of TVA's hydroelectric dams are located, rainfall was 31 percent higher than normal, according to figures from the National Oceanic and Atmospheric Administration.
Much of that rainfall occurred in July. Across the state, rainfall totals averaged a little more than 7 inches in July, about 58 percent above normal.
The rainfall led to a record-setting year for TVA's hydroelectric dams. The agency's 29 dams generated more energy during its 2013 fiscal year than at any other time in the past 80 years.
Power generation also was up for the U.S. Army Corps of Engineers dams on the Cumberland River that contribute to TVA's system. The eight dams produced power at 111 percent of normal capacity, according to figures provided by TVA. Four dams owned by Alcoa also contributed to the output.
TVA is charged with maintaining water levels on the Tennessee River and dozens of reservoirs throughout the region. In the summer, the agency usually focuses on keeping the reservoirs usable by boaters and channels navigable.
In July, TVA found itself with an unusual problem. At the peak of the water recreation season, when the agency typically is trying to keep water levels at reservoirs from getting too low, a week of heavy rain in much of East Tennessee resulted in the opposite problem: record high water levels.
"It's a big balancing effort," said Travis Brickey, a Knoxville-based spokesman for the agency. "We typically don't get that much rain in July."
As TVA spilled water at its dams to avoid flooding, its hydroelectric generators were humming along at full capacity.
Despite the spilling, so much rain came that the agency was forced to temporarily close some recreational areas because the water got so high.
Typically, hydroelectric power makes up between 8 and 10 percent of the power produced by TVA generation sites. In 2013, that percentage spiked to 13 percent, the agency reported.
The boost in hydro power in recent months has allowed TVA to purchase less energy from more expensive sources, said Scott Brooks, a Nashville-based TVA spokesman. The pattern is likely to continue this month.
The agency is predicting even more rain in December will push hydro generation 42 percent higher than in the same month a year earlier.
As a result, TVA's portion of local power bills this month will be 7 percent lower than in December 2012, Brooks said. The savingslikely will be passed on to consumers.
And while energy prices typically spike during the last month of the year, the extra supply of cheap power will make this December's rates only slightly higher than last month's, Brooks said.