Venturi turbine

A patented Venturi-turbine system developed by Mr. Aaron Davidson and Mr. Craig Hill of Tidal Energy Ltd., Australia, increases turbine efficiency by up to 3.84 times compared with the same turbine in free stream without the Venturi. In the Davidson-Hill design, Venturi is a key component used to create a faster flow across the turbine, increasing turbine efficiency and output power. The technology can also be used to pump water, for desalination, and for hydrogen production using electricity and electrolysis process.


The DHV turbine can be mounted on a monopile on the seabed where surface events such as large ocean swells and sea chop might buffet the turbine. It can also be slung under a pontoon on a swing mooring or be flown like a kite under water. In each case, power is cabled to shore for use. The company is now commencing the commercialization stage, with an expected price that competes with coal. Advantages of the DHV turbine include:


• The turbine is protected from potential damage inside the Venturi;
• The Venturi becomes part of the structural load sharing design;
• Bio-fouling is less due to the higher velocity inside the Venturi; and
• Easily mass-produced, and flat-packed and shipped anywhere for final assembly and installation.


Contact: Mr. Aaron Davidson, Tidal EnergyLtd., Gold Coast, Queensland, Australia. E-mail: tidalenergy @yahoo.com.au.


Source: www.peswiki.com
Wave energy buoy

OE Buoy, from Ocean Energy Ltd., Ireland, is a new wave energy device. In this model, air contained in the plenum chamber is pumped out and drawn in through the turbine duct by the movement of the water-free surface within the device. The hull’s motions enhance the relative surface movement and increase the air flow. The wave energy capture efficiency is high in normal wave conditions. Capture efficiency however, reduces during extreme waves when power levels exceed the capacity of the power take-off system. This makes the device self limiting and will ensure good survivability.


The power take-off system is a self-rectifying type air turbine that converts the flowing air into rotational energy, which drives the generator. The whole power take-off system contains only one moving part. All of the power take-off is above the waterline and not in direct contact with the sea water. This results in a reliable power conversion system. The electrical controls and ancillary systems are all contained within the sealed buoyancy chamber. The air chamber is fitted with a relief valve, which protects the turbine from over-pressure and runaway in extreme wave conditions. This will ensure safe operation of the turbine system during storms. Advantages of the OE buoy include: minimal mooring forces and thus vastly improved survivability; simple design and easy installation; low maintenance; and ease of location. Contact: Ocean Energy Ltd., 3 Casement Square, Cobh, Co. Cork, Ireland. E-mail: oceanenergy@o2.ie.



Source: www.oceanenergy.ie
Multi-device energy generation plant

The multi-device energy plant, developed by Ing. Arvid Nesheim from Norway, sports a water turbine that captures kinetic energy in waves and currents in oceans, rivers and streams, and converts the energy into electricity. The energy device consists of buoyancy items, an electrical generator, a frame structure with guide vanes surrounding a rotating cylinder that carries pivotably mounted turbine blades, side panels and a water inlet. Pressure difference between the “front” and “back” side of the device owing to waves or water current causes water flow through the device through the water inlet, past the turbine blades and out through the side panels. The flow of water creates a rotational motion that is transferred to the electrical generator to produce electricity.


The device is moored to a modular buoy system that is arranged to minimize the mooring line forces and horizontal displacement of the device. It can be positioned below the ocean surface to avoid drifting objects and weather conditions. The device is claimed to have low costs of fabrication, and be easy to deploy and operate. It can be equipped with a heat pump to convert the thermal energy in the ocean into other useful forms of energy.


Source: www.anwsite.com
Researchers test ocean waves for
energy

Researchers at the Air Force Academy, the United States, are developing a novel idea to generate energy from ocean waves. The devices used to extract the energy look like the paddle wheels on old river steamships, but featuring some new twists added by Mr. Stefan Siegel, a researcher, along with aeronautics research centre director Mr. Thomas McLaughlin. They envision submersible barges lined with the wheels that would be able to use the movement of ocean water to generate electricity and transmit it to shore over submerged cables.


Key to the invention is the idea that the blades on the paddle wheels will act like wings and can be steered to deal with different conditions of the sea. The wheels would also be designed to work in pairs that spin in opposite directions to cancel out the power of the waves against the submerged barge. Scores of designs to generate electricity from ocean waves have already been tried with limited success. The main problem with moving water is it can rapidly change intensity and direction. By submerging the generating plant and permitting it to move with the waves, though, Mr. Siegel thinks he has those problems solved.


Source: www.gazette.com
Offshore power generation and
storage technology

Neptune Systems, the Netherlands, has developed the technology for offshore power generation and storage through magneto hydrodynamical (MHD) ocean current conversion. This concept is based on the direct interaction between a magnetic, electric and fluid flow field, discovered by Michael Faraday – when a conductive fluid moves through a magnetic field, electrical power is generated directly, inside the fluid volume.


In marine applications, the sea water itself is the conductive fluid. A static antenna-like structure generates the magnetic fields and, at the same time, taps the electrical power from the fluid current. The most favourable configuration for generating a magnetic field, the company found, is a single (or alternatively multiple Helmholz) solenoid, superconducting DC coil. Superconduction helps eliminate Ohmic losses. The power necessary to drive the cryo-cooler is much less than the electric power produced. The configuration resembles a dynamo, the sea water being the rotor and the antenna the stator.


A main advantage of MHD conversion is the absence of moving mechanical (drive train) components, which make contemporary systems vulnerable and maintenance demanding. These aspects are especially important in the hostile (marine) environment. The focus of attention has been on the operating principles to generate the magnetic field. To gain more insight in the feasibility of the concept, a technical audit was organized with six known experts, who judged that there are no technical barriers to block the feasibility of Neptune MHD current conversion. Contact: Neptune Systems, P.O. Box 8719, 4820, BA Breda, The Netherlands. Tel: + 31 (76) 5433 565; Fax: +31 (76) 5433 566; E-mail: info@neptunesystems.net.


Source: www.neptunesystems.ne
Underwater vertical axis windmill

The Blue Energy ocean turbine acts as an efficient underwater vertical-axis windmill. The turbine, from Blue Energy International Inc., Canada, has four fixed hydrofoil blades connected to a rotor, which drives an integrated gearbox and electrical generator assembly. The turbine is mounted in a sturdy concrete marine caisson, which anchors the unit to the ocean floor, directs flow through the turbine to further concentrate the resource supporting the coupler, gearbox, and generator above it. These sit above the surface of the water and are readily accessible for maintenance and repair. The hydrofoil blades employ a hydrodynamic lift principal that causes the turbine foils to move proportionately faster than the speed of the surrounding water. Computer optimized cross-flow design ensures that the rotation of the turbine is unidirectional on both ebb and flow of the tide.


Power transmission is by submersible cabling and safely buried in the ocean sediments with power drop points. A standardized production design makes the system economical to build, install and maintain. The Blue Energy Ocean Turbine can be arranged in four platforms:


• Micro Power System – a 5-25 kW assembly for domestic users;
• Midrange Power System – two 250 kW turbines, suitable for use in remote communities, industrial sites, resorts, etc.;
• Blue Energy Power System – for large-scale power production, multiple turbines linked in series;
• Mega Power System – a scaled-up version of the Blue Energy Power System, capable of producing many thousands of megawatts of power.


Contact: Blue Energy International Inc., Box 29068, 1950 West Broadway, Vancouver, British Columbia, V6J 1Z0 Canada. Tel: + 1 (604) 682 2583; E-mail: inform@bluenergy. com.


Source: www.bluenergy.com