Rubber salmon, algae-fuel updates

Rubber salmon sate scientists' appetite for knowledge

Swirling waters rush over jagged rocks, swiftly propelling the salmon downstream towards the hydroelectric dam. Driven by the current making its push toward the ocean, the salmon is forced to navigate its way through the harrowing conditions inside the dam on its sojourn to mating waters in the Pacific. Turbine blades, high water velocities, the increase of dissolved gases and changing pressures all make for a frightening experience for any salmon — any real salmon that is.

Pacific Northwest National Laboratory's (PNNL) newest development, however, is definitely from a new school of thought. Operated by Battelle for the U.S. Department of Energy, PNNL has developed a rubber-encased battery of sensors, shaped like a juvenile salmon, that measures and records pressure, strain, acceleration and other hydraulic parameters that occur within the structure of a hydroelectric dam. The sensor fish are released upstream from the dam and directed through the turbines. The sensors provide previously unrecorded data concerning the rate and magnitude of pressures experienced during turbine passage, and they allow scientists to "see" what it is like to experience shear force, a severe condition that occurs when different water velocities collide. Shear force often causes a loss of scales, cuts or bruises or disorientation for salmon that weaken the fish and make them more susceptible to predators.

Recovered downstream where they are brought to the surface by flotation balloons, the mechanical fish are looked upon as an important step in reducing injuries salmon experience traveling through dams. Although less than 10 percent of fish incur direct damage, resource managers consider this amount unacceptably high.

For more information contact Tom Carlson at (503)417-7567 or via e-mail at

PSPG: Pond scum per gallon

Green algae, the type found in ponds and bodies of water all over the world, offers scientists a new hope in their search for a replacement of fossil fuels. The simple plant has the unique ability to convert water and sunlight into hydrogen gas. Hydrogen gas has shown promise as an almost limitless supply of fuel that burns without pollution and produces only water as a waste product.

When living in air and sunlight, green algae uses photosynthesis to produce the life-sustaining chemicals it needs, just like other plants. However, when algae is deprived of sulfur and is forced to live in an oxygen-free environment, the plant has evolved the ability to take up an alternative lifestyle. Instead of using photosynthesis and producing oxygen as a byproduct, green algae uses hydrogenase, an enzyme not found in higher plants, and sunlight to extract hydrogen form water.
At normal rates, one liter of algae culture produces three milliliters of hydrogen an hour, approximately a tenth of a fluid ounce. Researchers believe this efficiency can be increased at least 100-fold. According to scientists, algae growing in a small pond (size variable) could eventually be enough to power 10 cars.

This article originally appeared in the 03/01/2000 issue of Environmental Protection.

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