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The Leading Edge

Report on environmental effects of marine energy technologies

A draft report on the environmental effects of marine and freshwater hydrokinetic energy technologies is available for public comment on the Internet: report.html. These technologies are defined as those that do not use a dam, diversionary structure, or impoundment.

Comments will be accepted until December 5, 2008.

The draft report, prepared by Glenn Cada of Oak Ridge National Laboratory, is intended to address Section 633 of the Energy Independence and Security Act of 2007. This section calls for a report to be provided to Congress that addresses:

The draft report is based on literature reviews and information provided by technology developers, academia, state and federal regulatory and resource agencies, and nongovernmental organizations.

A final report will be submitted in June 2009 by the Secretary of the U.S. Department of Energy in conjunction with the Secretary of Commerce (acting through the Undersecretary of Commerce for Oceans and Atmosphere) and the Secretary of the Interior.

– For more information, contact Glenn Cada, (1) 865-574-7320; E-mail:

U.S. developers to explore wind-ocean hybrid projects

Hydro Green Energy LLC and Wind Energy Systems Technology Group (W.E.S.T.) jointly are exploring potential for the world’s first hybrid offshore wind-hydrokinetic ocean current projects. Hydro Green and W.E.S.T. envision using wind and water currents in the Gulf of Mexico to develop projects with a total capacity of nearly 5,000 MW.

The two companies signed an agreement in July 2008 that grants Hydro Green access to W.E.S.T. platforms and lease areas in the gulf for data gathering and possible testing. W.E.S.T. signed a lease agreement with the General Land Office of Texas in 2005 for its offshore wind projects, all located on submerged lands and waters owned by the state.

To better secure this exploration agreement with W.E.S.T., Hydro Green filed ten preliminary permit applications with the Federal Energy Regulatory Commission. If granted, the permits would give Hydro Green a three-year right to study the hydrokinetic portion of the projects, all in Texas waters.

Vortex Hydro developing VIVACE ocean energy converter

Vortex Hydro Energy in Michigan is developing the VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) converter. This unit harnesses the kinetic energy in ocean and river currents and tides.

VIVACE uses the energy contained in vortex-induced vibration to generate electricity. According to Vortex Hydro Energy, here’s how it works: Vibration results from vortices forming and shedding on the downstream side of a bluff body (such as a cylinder) in a current. (A bluff body is a structure where the drag is dominated by pressure drag; this is the opposite of a streamlined body, where the drag is dominated by frictional drag.) Vortex shedding – a situation where vortices are created at the back of a bluff body and detach periodically from either side of the body – induces oscillation or vibration of an elastic body.

The VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) converter features eight cylinders in a parallel arrangement, submerged in the ocean or a river. Waves induce vibration on the cylinders. This vibration can be used to generate electricity by converting it into linear motion using a linear generator.
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This vibration can cause serious damage to structures. Millions of dollars have been spent to blunt this destructive force. However, Vortex Hydro Energy says that by converting the motion caused by vortex-induced vibration into linear motion using a linear generator, it can be used to generate electricity.

VIVACE is designed to enhance vortex shedding, maximize vortex-induced vibration, and harness the resulting energy. The system consists of eight cylinders (the bluff bodies) in a parallel arrangement, located perpendicular to the flow of water. Vortex shedding produces lift on the cylinders, which are attached to the linear generator. VIVACE can operate in currents of varying speeds, including at speeds less than 2 knots.

The Marine Renewable Energy Laboratory (MRELab) at the University of Michigan developed the technology.

Vortex Hydro is developing a 3-kW prototype for testing in the Detroit River. The unit will be used to help provide electricity for a new wharf, pier, and building being built by the Detroit/ Wayne County Port Authority. Once funding for the work is received from the port authority, it will take 18 months to install the Vortex Hydro unit, says Michael M. Bernitsas, PhD, director of MRELab.

Two companies to receive leases for ocean energy test sites

Pacific Gas & Electric Co. (PG&E) and Aquantis LLC/Aquantis Development Co. Inc. have been approved by the U.S. Department of Interior’s Minerals Management Service (MMS) to proceed with ocean energy test area leasing. There were no competing applications submitted for these two projects.

PG&E will develop a wave resources data collection project in the Pacific Ocean off Mendocino County, Calif. MMS will proceed with leasing of the site while working with PG&E and local stakeholders to refine the area and scope of proposed activities.

Aquantis will develop an ocean current data collection project in the Atlantic Ocean off the southeast coast of Florida.

These leases are to be for five-year terms and will not convey any right or priority for commercial development, MMS says. They are to enable the lessees to collect information that would be useful for potential commercial projects developed under an MMS regulatory program.

MMS chose these two projects among 16 potential ocean and wind energy research projects within five areas offshore of California, Delaware, Florida, Georgia, and New Jersey. For another ocean energy site off California and three more sites off Florida, MMS said it intends to ask the multiple applicants to collaborate, rather than compete, in using these sites on the Outer Continental Shelf for the purpose of ocean energy data collection.

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