Tech Briefs

Sturgon passage facility installed at White Rapids

A prototype fish passage entrance channel designed to pass lake sturgeon and other fish is operating at We Energies’ 7.1-MW White Rapids project on the Menominee River in Wisconsin. Sturgeon passage presents unique challenges at hydro projects because these fish are bottom feeders and thus will not pass through structures located at the reservoir surface, says Scott Cevigney, supervisor of hydro operations for We Energies.

The entrance channel is attached to an existing concrete retaining wall in the tailrace. It simulates conditions expected from a permanent entrance. The entrance is 9 feet deep, 5 feet wide, and 36 feet long. The entrance portal features hinged side panels and a sloping floor rack that extends to the bottom of the river. The immersed depth of the floor rack is 5 to 6 feet at normal tailwater levels and a river flow of 3,600 cubic feet per second. To provide attraction flow, We Energies attached a steel collar at the upstream end of the entrance channel to capture and entrain discharge from Unit 1. To provide additional attraction flow, the entrance channel contains a 40-horsepower electric mixer pump, with screens to prevent fish entrainment.

A fishway engineering consultant for the U.S. Fish and Wildlife Service (FWS) provided the conceptual design for the channel. Personnel with We Energies and Black and Veatch provided detailed engineering of the structure. An engineer with We Energies and a local contractor installed the entrance channel.

The prototype fish passage entrance channel installed at We Energies’ 7.1-MW White Rapids project will be tested in 2009 and 2010 to determine if it will attract lake sturgeon. Click here to enlarge image

We Energies began planning to evaluate the costs and feasibility of installing passage structures for sturgeon at the White Rapids project in 1993. This effort was part of the Federal Energy Regulatory Commission relicensing proceedings for the White Rapids project. The FWS, Michigan Department of Natural Resources, Wisconsin Department of Natural Resources, National Park Service, Michigan Hydro Relicensing Coaltion, and River Alliance of Wisconsin were members of the planning team. Before completing detailed planning of a specific upstream fish passage structure, the team agreed that it is critical to determine that sturgeon will be attracted to and enter an entrance channel.

Based on preliminary investigations performed in 2008, We Energies plans to use an antenna system supplied by Biomark to evaluate the effectiveness of the fish entrance. The antenna will detect passive integrated transponder (PIT) tags, which are present in about 20 percent of lake sturgeon in the Menominee River below White Rapids. As a backup method, the utility will install two underwater cameras supplied by Cyberzone to record and verify sturgeon behavior near the entrance channel. This monitoring equipment is scheduled to be installed by mid-April 2009, with monitoring to take place in April and May 2009 and 2010.

– By Scott Cevigney, supervisor of hydro operations for We Energies, and James D. Fossum, consultant to the River Alliance of Wisconsin and the Michigan Hydro Relicensing Coalition

Columbia Basin salmon returns surpass ten-year average

Numbers of six of the seven salmon and steelhead stocks tracked at the 1,076-MW Bonneville hydro project increased in 2008, according to data from the U.S. Army Corps of Engineers’ Columbia River DART (Data Access in Real Time) website. For example, sockeye returns were about 213,600, more than 3.5 times higher than the ten-year average. Coho returns were about 135,500, 48 percent higher than the ten-year average. Overall chinook returns (spring, summer, and fall chinook) were about the same as the ten-year average.

The Corps, U.S. Department of the Interior’s Bureau of Reclamation, and Bonneville Power Administration (BPA) work as partners to help provide safe passage for fish and to meet the multiple purposes of the dams in the Columbia Basin. These coordinated efforts, along with other factors, appear to be working, says Nola Leyde, fishery planner with the Corps. NOAA Fisheries Service – the regulatory agency overseeing the Endangered Species Act for anadromous fish – says the recent high returns likely are the result of improved ocean conditions, improved operations and facilities for passing juvenile fish downstream, and substantial increases in the number of hatchery fish released in 2006 and 2007.

The high increase in sockeye returns is due in part to the reintroduction of sockeye to Skaha Lake on the Okanogan River in British Columbia, says John Skidmore, with environment, fish, and wildlife for BPA. From where the Okanogan River joins the Columbia River near the 2,457-MW Chief Joseph project in Washington, the fish travel about 400 river miles to Bonneville Dam, the last dam on their journey to the Pacific Ocean.

Skidmore says the higher coho returns likely are due to the reintroduction of coho in the mid-Columbia, upper Columbia, and Snake River basins.

Since 1991, about $1.2 billion has been spent on fish passage improvements under the Columbia River Fish Mitigation Program. The Corps expects to spend an additional $400 million to $500 million over the next ten years on structural improvements. In addition, the federal agencies expect to spend about $700 million in 2009 by partnering with tribes and states to make habitat improvements and hatchery reforms and to operate the hydro system for safe fish passage.

New turbine design under development

A new turbine design is being tested at Iowa State University that has the potential to decrease fish mortality and improve downstream water quality, says David T. Kao, PhD, chief executive officer of Innovide International, Inc. This new design, called the Kao updraft divergent flow turbine, allows water to flow upward through a divergent runner chamber and exit at the free surface near the tailwater elevation (see Figure 1).

Figure 1: The Kao updraft divergent flow turbine allows water to flow upward through a divergent runner chamber and exit at the free surface near the tailwater elevation. A vertical flow control needle replaces wicket gates. Click here to enlarge image

The basic principle behind this new design is that the same amount of energy carried in flowing fluid of a given rate of discharge and effective water head can be converted into mechanical power regardless of which direction the water flows through the turbine, Kao says.

Kao began developing this new turbine in 1982 while he was a faculty member at the University of Kentucky. Kao and his colleagues first built and tested an 8-inch model of the turbine from 1984 to 1987. In 1988, Kao was appointed dean of engineering at Iowa State University. In 1994, after continued design improvements, a modified 8-inch pilot unit was built and tested at Iowa State. From 1995 to 1999, repeated experimental work on the pilot unit and tests of fish survival were conducted at Tsinghua University in Beijing, China. Over that same time period, Kao’s team developed a 2-meter-diameter, 3-MW prototype and performed theoretical analyses and computational fluid dynamics (CFD) simulations.

The results of these tests confirmed the design objectives of the new turbine in terms of lightweight construction, kinetic energy recovery, fish friendliness, and exit flow mixing and aeration. In addition, CFD results revealed a smooth flow transition within the runner channel, which minimizes blade vibration and improves turbine operating efficiency.

In 2000, Kao left Iowa State University and founded Innovide International to focus on the continued development and industrial application of the new turbine.

In November 2008, work was completed on a 7-kW unit. Researchers are now developing low-power prototypes in capacities of less than 10 kW, less than 100 kW, and less than 1 MW. Additional laboratory and on-site testing will be performed on these units to further test their operational characteristics and to obtain additional fish safety and water quality data.

Eventually, Kao and his team plan to build a 3-MW turbine, which was already designed and analyzed using CFD simulation.

Kao says reversing the flow direction provides many benefits, including:

    – Eliminating flow cavitation, a major cause of fish mortality, by allowing the water to exit at the free surface;
    – Increasing dissolved oxygen in the turbine discharge through aerating mixing and air entrainment of the outflow water at the tailwater surface;
    – Providing partial balancing of machine weight and hydraulic pressure, which allows a lighter turbine and support structures;
    – Using a vertical pressure-balanced flow control needle valve instead of wicket gates, which reduces turbine flow turbulence and turbine weight, increases generating efficiency, and minimizes mechanical injury to fish; and
    – Recovering remnant kinetic energy, aided by gravitational deceleration of flow velocity through the upward divergent flow chamber, without requiring a costly draft tube.

Glossary provides definitions of common hydropower terms

Hydro Review offers the Hydropower Glossary, a 12-page booklet containing definitions for about 300 terms commonly used in conjunction with hydropower. This glossary can be a useful tool to those new to hydro, as well as a valued reference piece for industry veterans, according to members of the magazine’s advisory board, which helped develop the definitions.

Click here to enlarge image

Terms defined in the glossary cover a variety of themes, including civil structures, electrical issues, environment, equipment, and hydraulics.

– To order single copies of the glossary for US$25, contact Glenda Harp, (1) 918-831-9776; E-mail: Discounts are available for quantities of ten or more.

Asphalt concrete core dam built in Québec

Hydro-Québec has completed construction of a dam with an asphalt concrete core, the first in North America, says Marie-Elaine Deveault, press officer with Hydro-Québec. Although Hydro-Québec has been considering using this technique since 1980, the utility did so for the first time with Nemiscau-1 Dam, which was completed in October 2008, Deveault says.

The dam was built as part of the partial diversion of the Rupert River, a key component in the utility’s 768-MW Eastmain 1A and 138-MW Sarcelle powerhouses and Rupert diversion project.

The first dam with an asphalt concrete core was constructed in Germany in 1962. An asphalt concrete core dam is used as an alternative when building a dam in an area that lacks till. (Till is glacial drift consisting of a mixture of clay, sand, gravel, and boulders.) Although till was available for construction of Nemiscau-1 Dam, Hydro-Québec chose to adopt the technique as a prototype for future dam sites with insufficient till.

The asphalt concrete used in the core of Nemiscau-1 Dam contains a binder consisting of 7 to 7.6 percent bitumen, about 2 percent more than is contained in the asphalt used to build roads. This allows the asphalt to remain flexible at low temperatures while being extremely watertight, Deveault says.

The asphalt concrete mixture for Nemiscau-1 was prepared at an on-site plant. The mixture was produced at temperatures between 156 and 170 degrees Celsius, making it liquid so that it would fill the spaces between the aggregate particles, Deveault says.

Before any asphalt concrete was placed, contractors poured a concrete slab over the dam’s rock foundation. They then manually placed a mixture of asphalt and aggregate, known as mastic asphalt, in a 10-millimeter-thick layer directly on the concrete slab. A specially designed continuous paving machine laid the 600-millimeter-wide asphalt core, while simultaneously placing the transition zones on either side of the core. Concrete lifts 225 millimeters thick were placed in this fashion, with an average of two lifts being placed per day. The core was compacted after each lift.

The remainder of the rockfill dam was constructed using conventional methods. The finished dam is more than 300 meters long and 14.2 meters high.

Enterprises Kolo Veidekke Québec and Pavex Ltée built the asphalt concrete core for Nemiscau-1 Dam. This work involved placing 54 layers of asphalt concrete over a two-month period.

Selim Chacour elected to National Academy of Engineering

Selim A. Chacour Click here to enlarge image

Selim A. Chacour, president and principal founder of American Hydro Corporation in York, Pa., was elected to the U.S. National Academy of Engineering in February 2009. The citation was given “for pioneering three-dimensional fluid-dynamic finite-element computations, leadership in hydro turbine research, and business stewardship.”

The National Academy of Engineering is an independent, non-profit institution. Its 2,246 members are elected by their peers for seminal contributions to engineering, says Diane F. Hake, marketing assistant with American Hydro.

Chacour began his career with Allis-Chalmers. By 1970, he had developed a three-dimensional finite element code – called Danuta – that is still used today in the hydro industry, Hake says. In addition, Allis-Chalmers licensed the code to McDonnell-Douglas for aircraft analysis and to the Canadian Nuclear Power Industry for analysis of nuclear power plant components.

Chacour has contributed to the design of many hydro units, including the Francis turbines at 6,809-MW Grand Coulee in Washington and 2,078.8-MW Hoover between Arizona and Nevada, and the pump-turbines at 1,065-MW Bad Creek in South Carolina, 2,316-MW Bath County in Virginia, 1,600-MW Raccoon Mountain in Tennessee, and 636-MW Smith Mountain in Virginia.

In 1986, when Allis-Chalmers sold its hydro turbine division to Voith of Germany, Chacour founded American Hydro.

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