Many companies throughout North America are increasing hydro capacity by retrofitting and/or expanding existing projects, adding powerhouses at non-powered dams, and installing fish-friendly turbines. These methods are attractive because they avoid environmental concerns, and much of this work is eligible for federal funding.
By Ucilia Wang
In the U.S., a national focus on boosting renewable electricity generation has created a flood of project financing and research work.
One example is Alcoa, which has nearly 3,000 MW of capacity to provide for the needs of its smelting and refining system, as well as regional wholesale markets. Among its facilities is 122-MW Cheoah in North Carolina, which was poised to undergo a retrofit when the federal government passed the 2009 American Recovery and Reinvestment Act (ARRA). In August 2010, Alcoa resumed construction on the $120 million modernization after securing $12.9 million from the U.S. Department of Energy (DOE).1
Work on this project began in mid-2008 but stalled. "The economic crisis hit us hard, and we had to put it on hold," says Bill Bunker, vice president of hydropower at Alcoa Power Generating. "Thanks to the DOE money, we are back on."
Other companies have benefited from the government largesse, including Voith Hydro, supplier of the turbine-generators for Cheoah. In addition, the company is supplying the equipment needed to more than double the capacity of PPL's 108-MW Holtwood project in Pennsylvania.2 This $434 million expansion will increase plant capacity by 125 MW and improve fish passage along the Susquehanna River, said PPL. The company postponed and then restarted the project to take advantage of the ARRA programs to award tax credits and grants for renewable energy projects.
The government's interest in promoting renewable energy also creates new technology development initiatives. In March 2010, DOE, the U.S. Department of Interior, and the U.S. Army Corps of Engineers signed a memorandum of understanding to collaborate on technologies that will increase hydroelectric generation while minimizing environmental impacts.
But the hydropower industry hasn't received nearly as much funding as other renewable technologies, notably wind and solar. Industry groups such as EPRI and the National Hydropower Association (NHA) have stepped up efforts to remind lawmakers that hydropower is a clean source of electricity worth more public investments.
In fact, untapped potential for hydropower generation in the U.S. could lead to nearly 14,000 MW added to the electricity supply by 2025, says Doug Dixon, a technical executive with EPRI. The country currently has about 75,000 MW of hydro capacity, he added. Both figures don't account for pumped storage.
NHA points to Navigant Consulting's report that estimates an added capacity of 11,250 MW to 19,900 MW during the same period, depending on whether a national mandate for renewable energy consumption exists.3
Dixon points out that the federal government has beefed up the annual budget for DOE's water power program in recent years. Funding was zero from 2005 to 2007, he says. In fiscal year 2008, $10 million materialized for the budget, which grew to $40 million in 2009 and $50 million in 2010.
"The fact is that hydro is renewable," says Bunker with Alcoa. "It's green power going into the grid. Legislators are starting to realize that."
Remaking Cheoah Dam
One of the main focuses of new hydro development in the U.S. is adding capacity to existing dams. Many dams built initially for flood control, irrigation, and recreation are attracting interest from communities looking for new job-creating opportunities and affordable clean power. This added capacity can take two forms: increasing capacity at existing powerhouses and building new powerhouses at non-powered dams.
Cheoah is an example of the first form of expansion. Construction of the Cheoah project was completed in 1919. Alcoa is replacing four of the five Francis turbine-generator units at the plant. In addition to equipping the plant to operate reliably for years to come, this work will allow Alcoa to increase capacity of the plant by 22 MW.
"One benefit we are getting is the increase in turbine efficiencies," says Bunker. "We will use less water to generate more power."
The DOE money is a matching fund to replace two of the units. Installation of these units, along with a substation, is scheduled for completion by the end of 2012, Bunker says. After that, Alcoa will replace the two other units. The fifth turbine-generator, installed in 1949, does not require replacement.
|The 128-MW Cheoah project, on the Cheoah River in North Carolina, is one example of a plant that is being modernized using American Recovery and Reinvestment Act funding. Project owner Alcoa received $12.9 million from the U.S. Department of Energy.|
AMP adds hydro powerhouses
American Municipal Power (AMP) provides an example of the second type of expansion. The company is working to build five powerhouses at non-powered dams along the Ohio River.4 AMP already has one project, 42-MW Belleville, operating. Another project the company is working on is at Smithland Locks and Dam. The Smithland project will cost more than $400 million to add 72 MW of capacity and is scheduled to begin producing electricity in spring 2014.
Two other projects under way are taking place at the Captain Anthony Meldahl Locks and Dam and Cannelton Locks and Dam. Overall, AMP expects to build more than 385 MW of capacity through the six projects.
Dixon with EPRI notes almost all proposed projects to add electricity production to previously non-power-generating dams have come from private developers, including, in the case of AMP, those that are taking place at federal dams. A 2007 Corps survey showed that 1,230 MW can be added to federal dams without power production, and an additional 1,283 MW could come from modernizing old powerhouses at other federal dams.
There is a drive to combine more efficient turbines with fish-friendly technology. Although diverting water from the turbines to help juvenile fish move downstream decreases power production, this is one of the primary methods for ensuring fish passage at dams, says Thomas Carlson, a senior scientist with Battelle at Pacific Northwest National Laboratory (Battelle operates the lab under a federal contract).
In fact, studies show that this bypass spill gives fish the highest survival rate but is also the most expensive method.5 Bonneville Power Administration once estimated spills cost $1.2 billion in revenue between 1978 and 2001 among federal operations on the Columbia River.
"The serendipity is there are designs that optimize power and also provide benefits for the fish," Carlson says.
Researchers and engineers rely on computer and physical modeling to assess which turbine designs can boost both power production and fish survival. They play with blade shapes, numbers, and rotational speed, as well as the gap between the blades, to minimize the number of fish strikes.
Turbine efficiencies, which currently are in the mid-80 percents, can get up to the 90s, Carlson says. At the same time, it is possible to reduce fish mortality to 2 to 5 percent, given the combination of turbine technology and configuration of the dam, he adds.
Voith Hydro is working on two projects to design fish-friendly turbines. Headed by EPRI and funded by DOE and industry, the first project involves developing mechanical and other equipment for a conceptual and radical turbine design from Alden Research Laboratory, says Jason Foust, a hydraulic engineer at Voith Hydro.
Instead of the 13 to 17 blades that are common in Francis turbines, the Alden turbine uses three blades, Foust says. The Alden blades also are longer and taller to accommodate the necessary pressures, shear rates, and pressure change rates to allow for safe fish passage, he adds.
The project will soon demonstrate whether the turbine can deliver ample power while reducing harm to fish. Engineering and modeling work is scheduled for completion in 2011.
Although the turbine can become a candidate for powerhouse retrofit projects, it's "not the favorite because it's not a drop-in unit but will result in a reconfiguration of the powerhouse," notes Dixon. "That can be expensive."
Voith Hydro also is under contract to deliver two turbines for 603-MW Ice Harbor on the Snake River in Washington State. The Corps announced an $11 million award to the company in March 2010. Improving fish survival rates is the primary goal of the project, which sets out to develop a Kaplan turbine with a new propeller design. Engineers are looking at reducing the number of blades to four to seven, Foust says.
This article was previously published on the Renewable Energy World website at www.renewableenergyworld.com. This website publishes news online daily on all forms of renewable energy, including hydropower, ocean, solar, wind, and geothermal.
- Ingram, E., "Using Stimulus Funds to Advance Hydro Development," Hydro Review, Vol. 29, No. 3, April 2010, pages 18-30.
- Porse, N. Christian, "Taking Holtwood into the Next Century," Hydro Review, Volume 29, No. 4, June 2010, pages 8-20.
- Radhakrishnan, Rakesh, "Study: Hydropower Potential Could Create 1.4 Million Jobs," Hydro Review, Volume 29, No. 7, October 2010, pages 16-23.
- Meier, Phil, Paul Blaszczyk, Craig Harris, and Kirby Gilbert, "From Concept to Construction: Steps to Developing a Hydro Project," Hydro Review, Volume 29, No. 3, April 2010, pages 42-56.
- Coutant, Charles C., Roger Mann, and Michael J. Sale, "Reduced Spill at Hydropower Dams: Opportunities for More Generation and Increased Fish Protection," Oak Ridge National Laboratory, Oak Ridge, Tenn., 2006.
Canadian development spurred by feed-in tariff
In Canada, the majority of the hydroelectric development involves new greenfield projects. Developers in this country may be able to take advantage of a feed-in tariff, which offers unique incentives for hydro and other renewable electricity. Many say a feed-in tariff is one of the best ways to supercharge clean power development.
For example, Ontario's feed-in tariff policy, enacted in September 2009 as part of the Green Energy Act, sets premium prices for renewable electricity.1 This tariff has created a flood of proposed projects, notes Kaz Borovszky, business development manager for power generation at ABB. ABB provides power and automation technologies to many industries, including hydro.
Since the tariff was enacted, the government has approved 42 small hydro projects (10 MW or less), Borovszky says. Under the new tariff, hydro producers are paid 13.1 cents per kilowatt-hour for up to 10 MW and 12.2 cents for 10 to 50 MW. The cap on project size is meant to encourage eco-friendly development that doesn't involve a large reservoir or dam.
- Ray, Russell W., "Green Energy Act Energizes Ontario's Hydro Market," Hydro Review, Volume 29, No. 4, June 2010, pages 54-57.
Ucilia Wang is a California-based freelance writer who covers renewable energy technologies and policies.