Caption: Glen Canyon Dam
PAGE, Ariz. (AP) - The U.S. Bureau of Reclamation is wrapping up a project to replace the giant turbines that produce electricity at Glen Canyon Dam.
When the eighth one goes online later this year, energy production from the dam near the Arizona-Utah border is expected to increase by 3 percent, said Rick Clayton, of the bureau's Upper Colorado Region power office. The dam produces an average 4.3 million megawatt hours of energy per year, enough to power about 600,000 average households.
"It's a fairly small increase, but it's a benefit for the next 40 years," Clayton said.
The turbines were replaced one at a time after a contract was awarded in 2004, at a cost of $40 million, Clayton said.
Getting the turbines to the dam is no small feat. The 63-ton stainless steel turbines outweigh the old ones by nearly 20 tons and measure 16 feet in diameter. They were fabricated in Brazil and then shipped to the United States before arriving at the dam via train and semi-trailer. Each turbine was taken through a fairly tight 2-mile access tunnel at the dam that was blasted from the canyon wall when the dam was built so that excavated rocks could be dumped at the Colorado River. A crane lifted the turbines into place.
Energy is produced when water flows into eight penstocks that deliver it to the turbines that spin inside a pressurized case. When the water is released from the dam, the energy is captured and sent to an electrical switchyard on the rim of Glen Canyon. It gets sent to Nevada, Colorado, Nebraska, Arizona, New Mexico, Utah and Wyoming.
Visitors don't see the new turbines during tours of Glen Canyon Dam but they can view the generators they sit in through a window at the end of the tour. An old rusted turbine that was first to be replaced greets visitors as they step onto the quarter-mile concrete dam.
Tour guide Duane Berrier, a retired electrical engineer at the dam, said most visitors have a special interest in water or electrical projects. They come to Page from all over the world, he said.
"It's an impressive thing for anyone to see," he said.
The amount of energy generated from the dam can vary greatly based on level of water in Lake Powell, the country's second largest man-made reservoir following Lake Mead in Nevada. In 2014, the dam generated 3.1 million megawatt hours of energy. It saw its highest power generation ever in 1984 and 1985, with production around 8.8 million megawatt hours each of those years.
Hydropower peaks in July, August, December and January, but the power plant rarely runs at full capacity. Clayton said the water scheduled to be released from the dam, an average 8.2 million acre feet per year, has been manageable with less than eight units operating. At least one unit has been down during most of the high-flow experiments that the Bureau of Reclamation conducts to build up sandbars along the Colorado River through the Grand Canyon.
"We would like to have them all available," Clayton said. "It will be good once we finish this milestone."