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Sensor fish help protect migrating fish in Pacific Northwest rivers

March 2005
Data collected by a "crash test dummy" for fish will be used to modify hydropower plant operations to assure safer journey for young migrating fish. It is a balancing act-operating hydroelectric generating facilities efficiently and protecting the fish migrating from inland rivers to the Pacific Ocean. The Pacific Northwest National Laboratory is helping to strike that balance with its new six degrees of freedom sensor fish. From mid-February through mid-April, the new sensor fish will undergo its first field tests as it passes through the advanced turbine in the Wanapum Dam on the Columbia River near Beverly, Washington. The advanced turbine was manufactured by Voith Siemans and was newly installed by the Grant County Public Utility District. The sensor fish was developed by the Pacific Northwest National Laboratory under the Department of Energy's Energy Efficiency/Renewable Energy Hydropower Program. This sensor fish device is the latest generation of "crash test dummies" that researchers have sent on the short but often turbulent ride through the turbines spillways, and other downstream passage routes at a number of dams on the Snake and Columbia rivers in the Pacific Northwest. The sensor fish is actually a small plastic sealed tube about the length and mass of a live yearling salmon smolt, 3.5 inches long and 1.5 ounces in weight, and is neutrally buoyant in water. Packed inside the tube is a variety of compact electronics to measure the physical conditions experienced by fish that are not diverted from traveling through the dam. Twenty devices have been manufactured for the tests at Wanapum Dam. Crash test dummies collect data As with the crash test dummies that substitute for the driver and passengers in cars undergoing crash tests, the sensor fish measures the physical forces that act upon the live fish as it passes through the turbine. And just as information gathered from crash test dummies can affect automobile design with the installation of protective designs to lessen or prevent human injury, having sensor fish data to quantify acceleration, pressure changes, and the six directions of movement can influence the design and operations of turbines to reduce the harmful effects on the fish. The sensor system aboard the new six degrees of freedom sensor fish includes a triaxial linear accelerometer and a triaxial rate gyro, which together measure the six degrees of motion, or freedom-up-down, forward-back, side-to-side, pitch, roll, and yaw. The sensor fish also includes a pressure transducer, rechargeable battery, and analog and digital elements to filter, digitally sample and store data. Other supporting electronic modules charge the internal battery, download data, and reprogram the sensors to perform specific data acquisition tasks. Tom Carlson, scientist at Battelle's Pacific Northwest Division's Portland Office said, "The sensor fish data characterize the harsh environment the live fish experience when they pass through a turbine." Tough travel through turbines Physical barriers such as screens installed at many dams divert fish from the turbine intake. Within the dam, water from the reservoir turns the blades of the turbines, which activate the generators to produce electricity. The fish that elude the screens move with the force of the water through the turbines. Such a trip includes tremendous, quick changes in water pressure and in water velocity, not to mention the possible cutting and bruising the turbine blades can cause. A trip through the turbines may also cause internal injury, and damage to eyes and gills. Once they exit the dam, the fish often are often dazed and can be easy targets for predatory fish and birds. In tests at the dams, the six degrees of freedom sensor fish will be deployed through 100-foot-long, 4-inch-diameter water-filled pipes to the intake passages of the dam. Gravity takes the device into the dam, where it passes through the turbines, and exits the dam. On-board radio transmitters and balloon tags aid the recovery of the devices below the dam. Live tagged fish are deployed with the sensor fish, allowing researchers to compare the condition of the fish with the data collected by the sensor fish. Data effect hydropower generation changes "The turbine being tested at Wanapum Dam is designed to generate more power while providing a safer passage for fish. This advanced-design turbine has an improved runner design and minimum blade gaps, among other features, to increase both the hydraulic capacity of the turbine and the survival of fish that travel through the turbine," said Dennis Dauble, PNNL program manager for the U.S. Department of Energy Wind/Hydropower Program. "Using the sensor fish in these tests helps support DOE Hydropower program's goals to increase power production without building new dams and to avoid deleterious environmental effects." Until 1997, when PNNL developed the first generation of the sensor fish, engineers and dam operators relied upon physical and numerical models of the dams to evaluate turbine performance and observe fish migration in impounded rivers. With this latest generation of sensor fish researchers have the opportunity to gather data on the physical environment fish experience traveling through a dam. This information is leading to the design, testing, and operation of more fish-friendly turbines that will balance use of the Pacific Northwest's hydropower resource with the protection of its migrating fish. For more information contact: Dennis Dauble, Natural Resource Division Manager, or Tom Carlson, project scientist

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