Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Calculating tidal energy turbines' effects on sediments and fish

The emerging tidal-energy industry is spawning another in its shadow: tidal-energy monitoring. Little is known about tidal turbines' environmental effects and environmentalists, regulators and turbine manufacturers all need more data to allow the industry to grow.

Engineers at the University of Washington have developed a set of numerical models, solved by computers, to study how changing water pressure and speed around turbines affects sediment accumulation and fish health. They will present their findings this week at the American Geophysical Union's meeting in San Francisco.

The current numerical models look at windmill-style turbines that operate in fast-moving tidal channels. The turbine blade design creates a low-pressure region on one side of the blade, similar to an airplane wing. A small fish swimming past the turbine will be pulled along with the current and so will avoid hitting the blade, but might experience a sudden change in pressure.

Teymour Javaherchi, a UW mechanical engineering doctoral student, says his model shows these pressure changes would occur in less than 0.2 seconds, which could be too fast for the fish to adapt.

If the pressure change happens too quickly the fish would be unable to control their buoyancy and, like an inexperienced scuba diver, would either sink to the bottom or float to the surface. During this time the fish would become disoriented and risk being caught by predators. In a worst-case scenario, severe pressure changes could cause internal hemorrhaging and death.

It's too early to say whether tidal turbines could harm fish in this way, Javaherchi said. The existing model uses the blade geometry from a wind turbine.

"The competition between the companies is very tight and they are hesitant to share the designs," Javaherchi said.

The researchers are open to working with any company that wants to use the technique to assess a particular turbine design.

Another set of numerical modeling looked at whether changes in speed of water flow could affect the settling of suspended particles in a tidal channel. Slower water speeds behind the turbine would allow more particles to sink to the bottom rather than being carried along by the current.

Javaherchi's modeling work suggests this is the case, especially for mid-sized particles of about a half-centimeter in diameter, about two-tenths of an inch. This would mean that a rocky bottom near a tidal turbine might become sandier, which could affect marine life.

The UW research differs from most renewable energy calculations that seek to maximize the amount of energy generated.

"We are [also] interested in the amount of energy that can be extracted by the turbines, but we are aware that the limiting factor for the development of these technologies is the perception by the public that they might have a big environmental impact," said Alberto Aliseda, a UW assistant professor of mechanical engineering and Javaherchi's thesis adviser.

As to whether any negative effects discovered for tidal turbines would be preventable, Aliseda said, "Absolutely."

"We need to establish what is the lowest pressure that the animals can sustain and the period of time that they need to adjust," Aliseda said. "The blade can be shaped to minimize this effect."

Aliseda says engineers in the wind-turbine industry are already adapting the UW work to look at interactions between wind turbines and bats, since high-frequency pressure changes are now thought to be responsible for the mysterious deaths of bats caused by wind turbines.

"Maybe the best turbine is not the one that extracts the most energy, but the one that extracts a reasonable amount of energy and at the same time minimizes the environmental effects," he said.

The research was funded by a Department of Energy grant to the Northwest National Marine Renewable Energy Center. Joseph Seydel, a Boeing engineer and UW graduate in mechanical engineering, also contributed to the research.

For more information, contact Aliseda at or 206-543-4910 or Javaherchi at

More information about UW tidal energy research is at

Hannah Hickey | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>