Using US power need – to restore water ecosystems

Water is the leading renewable energy source used by utilities to generate electric power.

Along the Mississippi River, a city and a small startup firm have separate hopes of harnessing that artery’s energy potential either through a few big turbines or thousands of tiny, submerged ones. Moving water spins the blades of a turbine, which turns a generator shaft. A fall of less than 30 feet, the height of most Ohio River dams, is sufficient. The submerged turbines about two feet in diameter and perhaps made of carbon fiber or some other lightweight source durable enough to withstand being hits by debris swept downriver while not interfering with barge traffic. See image mississippi-river-hydrokinetic-power

Since 1913 at Keokuk, Iowa hydro- power has been used, but the future may see thousands of small electric turbines in the river bed at 55 sites from St. Louis to the Gulf of Mexico, figuring together they could generate enough power to supply 1.5 million homes.

The cumulative output of 1,600 megawatts would be the equivalent of three small coal-fired power plants or one or two nuclear ones.

Free Flow Power Company has screened some 80,000 river sites across the country and been given preliminary permits from the Federal Energy Regulatory Commission first rights to seek operating licenses for projects at those locations while giving it three years to do environmental and technical studies.

Instead of simply looking for power why not restore the ecosystem of the river and surround lands as much as possible.

Janet Sternberg, a Missouri Department of Conservation policy coordinator, urged FERC months ago to not move too hastily on such projects until more about hydrokinetics is known.

“We have no objection to the careful scrutiny and scientific question,” Irvin said. Stressing that Free Flow’s turbines would turn only with the speed of the river, “we’re pretty comfortable that what we’re proposing is going to be completely benign to fish.”(1)

Evaluating the geology, riparian vegetation, and focal species habitat along the river and begin to management, and eventual restore the river way habitat. Studying the watershed, as is develop the physical habitat template upon which to develop restoration strategies and the water turbines could be more costly true, but save in the long run for all living interdependent systems.

Do a Floodplain Restoration Feasibility Study maybe following the Stillwater Sciences system to provide an understanding of physical processes (hydrology and geomorphology), habitat dynamics, and biological resources within the watershed and developing a set of feasible restoration strategies given opportunities and existing constraints. This system is being used successfully on the Santa Clara River, Ventura County, California project. (2)

Yes, they have much less rehabilitation to do and at the moment they are not putting hydro-power in, but aspects of the project may be helpful and inspirational. -Mother Nature

Now here is another gentler possible solution for the fish.

Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power by using VIVACE (Vortex Induced Vibrations for Aquatic Clean Energy).

VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.vivace-vortex-induced-vibrations-aquatic-clean-energy-bg

Vortex vibrations are made by rounded or cylinder-shaped object makes ias it flows through air or water. The presence of the object diverts current’s speed causing eddies, or vortices, to form in a pattern on opposite sides of the object like one sees as water flows around a boulder or log submerged in a river. The vortices move the object in all directions perpendicular or at right angles to the current.

These vibrations in wind toppled the Tacoma Narrows bridge in Washington in 1940 and the Ferrybridge power station cooling towers in England in 1965. In water, the vibrations regularly damage docks, oil rigs and coastal buildings.

We want to harnesse these natural forces of water said VIVACE developer Michael Bernitsas, a professor in the U-M Department of Naval Architecture and Marine Engineering.

Fish have long known how to put the vortices that cause these vibrations to good use. “Fish curve their bodies to glide between the vortices shed by the bodies of the fish in front of them. Their muscle power alone could not propel them through the water at the speed they go, so they ride in each other’s wake.”

This generation of Bernitsas’ machine looks nothing like a fish, though he says future versions will have the equivalent of a tail and surface roughness a kin to scales. The working prototype in his lab is just one sleek cylinder attached to springs. The cylinder hangs horizontally across the flow of water in a tractor-trailer-sized tank in his marine renewable energy laboratory. The water in the tank flows at 1.5 knots.

The vortices push and pull the passive cylinder up and down on its springs, creating mechanical energy. Then, the machine converts the mechanical energy into electricity. Just a few cylinders might be enough to power an anchored ship, or a lighthouse, Bernitsas says. These cylinders could be stacked in a short ladder. The professor estimates that array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a river bed or it could dangle, suspended in the water. But it would all be under the surface.

Because the oscillations of VIVACE would be slow, it is theorized that the system would not harm marine life like dams and water turbines can.

Bernitsas says VIVACE energy would cost about 5.5 cents per kilowatt hour. Wind energy costs 6.9 cents a kilowatt hour. Nuclear costs 4.6, and solar power costs between 16 and 48 cents per kilowatt hour depending on the location.

“There won’t be one solution for the world’s energy needs,” Bernitsas said. “But if we could harness 0.1 percent of the energy in the ocean, we could support the energy needs of 15 billion people.”

The researchers recently completed a feasibility study that found the device could draw power from the Detroit River. They are working to deploy one for a pilot project there within the 18 months.
The technology is being commercialized through Bernitsas’ company, Vortex Hydro Energy.

1. Mandates driving surge to the river for hydropower – Terry Kinney and Jim Suhr AP St. Louis November 30, 2008.

2. Santa Clara River Parkway Floodplain Restoration

Stillwater Sciences is evaluating ecological conditions in the lower Santa Clara River to inform and develop a Floodplain Restoration Feasibility Study. –

3. Fish Technology Draws Renewable Energy From Slow Water Currents
University of Michigan College of Engineering –

Fish Technology Draws Renewable Energy From Slow Water Currents – Staff Writers Ann Arbor MI (SPX) Nov 27, 2008

image 3. An artist’s illustration of an array of VIVACE converters on the ocean floor.

Image:…/ 12/images/epa-map-zebra.gif


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