I recently read an interesting article about Oscilla Power, a Seattle-based company that makes wave power generators.

Oscilla’s wave energy harvesters are based on a phenomenon called magnetostriction, a property of some ferromagnetic materials to change their shape slightly in the presence of a magnetic field.

However, Oscilla applies this process in reverse – called reverse magnetostriction – by applying stresses or strains to the materials so their magnetic characteristics change.  When coupled with a generator that has permanent magnets and wire coils, the process generates electricity.

Oscilla owns a number of patents and pending applications covering its technology, including two related U.S. Patent Nos. 7,816,797, and 7,964,977, entitled “Method and device for harvesting energy from ocean waves.”

These patents are directed to a device (100) for harvesting energy from the oscillations of ocean waves (102).  The core modules of the device (100) include at least one buoy (104) attached to magnetorestrictive elements (106) via tethers (110).

The magnetorestrictive elements (106) are anchored to the seafloor or to another rigid body using anchors or weights (108).

According to the Economist piece, the magnetorestrictive elements are bars made from a strongly magnetic alloy of iron and aluminum.  These bars need be compressed only very slightly (one part in 10,000) to generate electricity.

Even such a tiny compression takes a large force when the bar is made of solid metal, but ocean waves have sufficient power to generate the required force and do so by oscillation.  Oscilla’s generators have two large objects connected by cables:

A buoy floating on the surface of the ocean contains the generating apparatus of alloy bars, magnets and coils, as well as sets of hydraulic rams which can squeeze the bars.  The cables connect the buoy to a heave plate maintained in a stationary position.

As the buoy rises and falls with the waves at the surface and the heave plate stays still, the tension on the cables increases and decreases.  The changing tension drives the rams and produces electricity.

Because the generators operate on changing tension, they don’t need to employ lot of moving parts and should therefore be more reliable than conventional wave power generators.

After a successful trial of a four-meter prototype last year, Oscilla hopes to build a full-scale device by 2018.

I received an interesting press release about something called Nautical Torque technology, a process for generating energy from the rise and fall of ships and other large vessels with the tide.  It was invented by the late Cahill Maloney; his son, Galen, is now carrying the torch.

The process is described and claimed in U.S. Patent No. 8,143,733, entitled “System and method for providing nautical torque technology” (‘733 Patent). 

The ‘733 Patent is directed to a system for nautical torque tidal movement power generation (100) comprising an arrangement (110) of modular, electrically interconnected power generating devices (120) positioned to receive kinetic energy from the movement of water.

Accelerator gearboxes (130) are mechanically coupled to large masses (113).  A torque conversion unit (160) includes an upper drive arm (161) coupled to one large mass (113), a lower drive arm (162 coupled to a second large mass (113), cotter pins (162), a circular sprocket (163), a guide sprocket (164), a reversible gear unit (165), pylons (166), and a circumference sprocket (167) coupled to the reversible gear unit (165).

According to the ‘733 Patent, this assembly generates energy when the large masses move up and down with a tidal movement of about one foot per hour:

[The system comprises] at least one tidal movement wave 112 wherein said tidal movement wave 112 travels at a rate of substantially 1 foot per hour in a substantially vertical translation such that said large particles of mass 113 floating on a surface of said tidal movement wave 112 would travel a total of one foot per hour . . . wherein said large particles of mass 113 produce movement of 1 foot per hour in a substantially vertical direction and transmit energy output to one or more electrical transmission power generating devices 120.

According to the Nautical Torque web site, Mr. Maloney is working on a prototype to demonstrate the scalability of the technology.  More info about the inventor and the project can be found here.

Ocean Renewable Power Company (ORPC) is Maine company that develops ocean and river power systems. 

According to this NRDC blog post, ORPC’s Cobscook Bay tidal energy project in the Bay of Fundy in Maine is the first in the U.S. to receive a FERC license, include a power purchase agreement, and install and operate a power-producing tidal generator.

ORPC’s tidal generators are modular turbine-generator units that can be stacked in various configurations for bodies of water of different depths.  The company has a RivGen model for small river sites, Ocgen for depths of more than 80 feet, and the TidGen for depths of 50-100 feet.

According to Cleantech PatentEdge™, ORPC owns at least seven U.S. and international patents and pending applications covering its tidal generator technology. 

U.S. Patent No. 7,902,687 is entitled “Submersible turbine-generator unit for ocean and tidal currents” and directed to ORPC’s modular unit (‘687 Patent).  The turbine-generator unit (400) includes a support structure (410) mounting a pair of turbines (420) coupled by a rotatable shaft (430) to a generator (600).

Each turbine (420) has airfoil-shaped blades (500) mounted transversely to the direction of fluid flow for rotation in a plane parallel to the fluid flow.  According to the ‘687 Patent, the turbines are capable of rotation under reverse fluid flow and rotate in the same direction regardless of fluid flow direction.

U.S. Patent Application Publication No. 2009/0129928 (‘928 Application) covers ORPC’s turbine structure.  Entitled “High efficiency turbine and method of generating power,” the ‘928 Application is directed to a turbine (100) having a plurality of blades (105) tracing a spiral wound path about a central shaft (110).

The blades (105) are connected to the central shaft (110) by a plurality of radial spokes (115), which are substantially perpendicular to the central shaft (110).  The blades (105) have an airfoil, or hydrofoil, shaped cross-section (200) with a leading edge (210), a trailing edge (220) and a centerline chord (230).

According to the ‘928 Application, the hydrofoil shaped cross section (200) preferably is asymmetrical, which helps generate maximum torque and thereby boosts efficiency.  In addition, the hydrofoil cross section (200) presents a non-zero angle of attack for generating lift and maximizing generated torque.

The latest ORPC project update here said the company’s TidGen turbine generator is nearly complete and being prepared for deployment.

 

Ecofys is Dutch renewable energy and climate policy consultancy that has developed a Wave Rotor tidal energy device. 

IHC Merwede, a Dutch company that focuses on design and construction solutions for the maritime sector, recently acquired the Wave Rotor technology.

The Wave Rotor technology enables IHC Merwede to launch a fully integrated system to generate electricity using tidal energy.   The technology will be managed by a newly established company called IHC Tidal Energy.

In contrast to most tidal turbines, the Ecofys Wave Rotor is vertically oriented, allowing the device to convert power from tidal currents and wave motion directly into electricity.

Ecofys owned at least two international patent applications relating to its Wave Rotor technology:

• International Patent Publication No. WO 2010/011133, entitled “A Device for the Utilisation of Wave Energy and a Method” (‘133 Application); and
• International Patent Publication No. WO 2010/062170, entitled “An Apparatus for Harvesting Energy From a Body of Water and a Method” (‘170 Application)

The object of both applications is to provide an improved wave power device whose energy efficiency is increased considerably, thus reducing the costs of the energy.

The ‘133 Application is directed to a tidal device that marries two types of rotor blades. More particularly, the device includes a Darrieus rotor having at least two Darrieus rotor blades, and a Wells rotor having at least two Wells rotor blades, wherein the Darrieus rotor and the Wells rotor are rotatable about a common axis.

The device comprises three Darrieus rotor blades (101) and three Wells rotor blades (102). The Wells rotor blades are attached at their distal ends to a central axle (104), which is connected to a generator (105) for generating electricity.

According to the ‘133 Application, combining both Darrieus and Wells rotor blades achieves a higher conversion efficiency than than a wave power device having only Darrieus rotor blades or only Wells rotor blades.

The ‘170 Application describes a similar device having both Darrieus and Wells rotor blades.

The device (100) comprises three Darrieus rotor blades (101) hingeably connected near the distal ends of the Wells rotor blades (102). The proximal end of each Wells rotor blade connects to the central axis (104), which is connected with a generator (105) to generate electricity.

The Darrieus blades (101) are arranged in a longitudinal direction and are connected at second points by connecting arms (122) to a lower point on the central axis.

The second connections between the connecting arms and the central axis are rigid connections, and are preferably shorter than the Wells rotor blades that connect the first points of the Darrieus blades with the central axis.

According to the ‘170 Application, the device has an improved capability of handling varying loads because it is rigid to such an extent that the driving forces exerted on the Darrieus rotor blades are transferred to the central axis effectively, yet bending moments in the rotor blades are reduced, in particular near the transition of the Darrieus rotor blades to the connecting arms.

With the newly acquired technology, IHC Merwede will further secure its position as a major maritime sector player, particularly in the renewable market.

*Jeff Woodley is a contributor to Green Patent Blog.  Jeff is a summer associate at McKenna Long & Aldridge and is currently in his final year at the University of California, Los Angeles School of Law.  He received his undergraduate degree in Economics also from the University of California, Los Angeles.

 

Hydrovolts, a Washington-based company, specializes in hydrokinetic turbines.  The company has created turbines that can be used to generate energy in canals, waterfalls, and remote locations.

Hydrovolts owns U.S. Patent Application Publication No. 2010/0237626 (‘626 Application), entitled “Hinged blade cross-axis turbine for hydroelectric power generation” and directed to a water turbine having pivotable blades.

Water turbine (120) is disposed in frame (110), and a turbine shaft axis (122) lies in the center of the frame (110).  The frame is connected to two electric power generators (105), found on either side of the device.

The technology’s pivoting blades (126 A, B, C & D), which Hydrovolts calls the flipwing rotor, differentiate it from most other turbines. As water (90) flows through the device, it comes in contact with blades that pivot around blade axes (125).

The pivoting nature of the blades allows for a high level of blade surface area to maintain contact with the water as it flows through the device.

According to the ‘626 Application, this innovation provides several important advantages.  First, less force is required to move each blade because each blade has its own axis in addition to a central axis.

Also, more energy can be harnessed than in a device made of the same amount of material without pivoting blades. 

Finally, lifting forces drive the device, allowing for it to operate in low flow conditions while many other turbines have a “stall-speed,” or minimum speed required to drive the device.

See a video of a Hydrovolts hydrokinetic turbine in action here and this Greentech Media piece about the company’s plan to generate hydropower from wastewater treatment plants.

Rosemary Ostfeld is a contributor to Green Patent Blog.  Rosemary recently completed both her undergraduate and graduate education at Wesleyan University in Middletown, Connecticut.  She double majored in Biology, and Earth & Environmental Sciences as an undergraduate, and received her Master’s in Earth & Environmental Sciences.

Alstom and SSE Renewables have signed a new joint venture agreement to co-develop the world’s largest wave farm in the Costa Head Wave Project, off the coast of Orkney, Scotland. The farm will deliver up to 200 Megawatts of renewable energy utilizing AWS Ocean Energy Ltd’s (AWS) Archimedes Wave Swing III technology (AWS-III).

AWS is based in Inverness, Scotland, and the company’s stated purpose is to develop and deliver the technology of choice for utility scale generation of offshore wave power.

AWS-III is described in U.S. Patent Application Publication No. 2011/0185721, entitled “Energy Conversion Device” (‘721 Application) and directed to an array of interconnected compressible cells which convert wave energy into pneumatic energy by moving air between the cells.  Turbines within the device convert the moving air into electricity.

Figure 1 of the ‘721 Application illustrates the wave energy device.  The device has twelve interconnected cells (20) arranged in a ring.  The cells are connected to a ring-like air duct (not shown) and have a diaphragm (30) on their outer edge. 
The diaphragm moves relative to the cell when wave action (40, 50) presses against the movable diaphragm surface.  The movement of the diaphragm causes air within the cells to be pumped into and out of the air duct and between the cells.  The moving air then spins a turbine, which produces electricity.

Each multi-cell array can produce up to 2.5 megawatts of electricity.  Once in place, the devices are moored to the sea floor in depths ranging from 60 – 150 meters.  Each device will be connected to the local utility grid from an offshore substation via a high voltage link.

According to a joint press release, a 1:9 scale model of the AWS-III was deployed in Loch Ness, Scotland in 2010.  Full scale component testing will commence in 2012 and a full scale prototype is planned for deployment in 2014.

In the press release, Simon Grey, Chief Executive at AWS stated:

The selection of the AWS-III system for this exciting and ground-breaking project is a significant endorsement of our technology and team.  We firmly believe that the AWS-III will become the established choice for utility scale offshore wave power generation.  We look forward to working with Alstom and SSE to deliver Costa Head.

AWS and Alstom predict there is a potential worldwide market for renewable wave energy in the 200 to 300 gigawatt range. If successful, this 200 megawatt wave farm will be a large step in making that prediction a reality.

David Gibbs is a contributor to Green Patent Blog.  David is currently in his third and final year at Thomas Jefferson School of Law in San Diego.  He received his undergraduate degree in Geology from the University of California, Berkeley.

 

Some recent green tech articles (e.g., this Ecogeek piece) have covered a mobile wave power system being developed by the Fraunhofer Center for Manufacturing Innovation (FCMI), a Boston applied research institution.

FCMI’s system is a large ship or power barge fitted with a vast amount of storage capacity such as advanced batteries integrated with wave energy generators.  The barge would go out to sea, deploy the wave energy generators in the water to charge the batteries, then withdraw the generators and return to port to connect the fully charged batteries to the grid.

FCMI and Boston University co-own International Application WO 2011/060183, entitled “System for wave energy harvesting employing transport of stored energy” (‘183 Application).

The ‘183 Application is directed to systems and methods of wave energy harvesting comprising a vessel (10-I) having a vessel body (33), which includes the basic ship features as well as a wave energy harvesting apparatus carried by the body (33).

The wave energy harvesting apparatus includes buoys (34) and mechanical linkages (36) connecting the buoys (34) to the vessel body (33).  In certain embodiments, the buoys (34) are “heaving” buoys which float in the water and rise and fall with the movement of the waves (arrow 38 indicates wave direction).

The vessel (10-I) is anchored or otherwise moored at a harvesting location.  The heaving of the buoys (34) is translated by linkages (36) to corresponding mechanical motion on the vessel body (33), which is then converted into a form of storage in the batteries carried by the vessel body (33).

Figure 1 below shows an overview of the method, which includes several modes.  In the harvesting/storing mode (12), wave energy is absorbed and converted into stored energy. 

In the transporting mode (14), the vessel travels to a releasing location, where, in releasing mode (18), the stored energy is used to generate electricity provided to an electrical grid (20).

Finally, in the returning mode (24), the vessel (10) returns to the harvesting location to start another cycle of operation.

According to FCMI’s web site, the mobile wave energy harvesting system has several advantages including obviating the need for expensive undersea power cables, ability to move the system safely to port during stormy weather, and avoiding regulatory hurdles associated with permanent structures.

Nautricity is a UK company that develops tidal energy technology.  Its CoRMaT tidal turbine, a 500kw device in its largest form, will be installed and tested in the Thames River alongside a former Royal Navy sloop called the HQS Wellington (see Clean Technica article).

The CoRMaT turbine is the subject of at least one international patent application, WO 2007/017629, and U.S. Application Publication No. 2008/0226450 (‘450 Application).

According to Nautricity’s web site, the CoRMaT turbine is the result of R&D conducted at the University of Strathclyde, which is the owner of record of the two patent applications.

The ‘450 Application is directed to a turbine (5) having two adjacent sets of coaxially mounted blades.  The first set (10) is coupled with a first shaft (20); the second set (15) is coupled with a second shaft (25).

The first shaft (20) is directly coupled with a rotor (45) of a generator (50), and the second shaft (25) is directly coupled with a rotatable stator (55).

The first set (10) of blades (65) contra-rotates relative to the second set (15) of blades (66).  This causes contra-rotation of the respective shafts (20, 25) and of the rotor (45) and the stator (55) of the generator (50).

According to the ‘450 Application, generator performance can be optimized by arranging the blade sets (10, 15) so one set cannot be completely eclipsed by the other at any point in the power generation cycle.

Nautricity’s web site describes the turbine technology as:

two closely spaced contra rotating rotors, driving a contra rotating electrical generator.  The first rotor has three blades rotating in a clockwise direction while the second rotor, located directly behind the first, has four blades rotating in an anti-clockwise direction.

According to Nautricity, the contra rotating rotor arrangement doubles the relative rotational speed compared to a single rotor turbine and splits the torque equally between the two rotors.

The torque-splitting eliminates reactive torque acting on the support structure, thereby allowing the turbine to be moored rather than rigidly attached to the seabed. 

Thus, the CoRMaT can be deployed in a variety of locations at depths varying from eight meters to 500 meters.

According to Nautricity’s press release, the trial is the first stage in a large project to site hundreds of tidal turbines along the river and generate enough electricity to power 35,000 homes.

Tidal Energy Limited (TEL) is a UK company that makes tidal power devices.  TEL recently received funding that it will use for a feasibility study of its “DeltaStream” technology and assess a potential deployment site for its device in West Wales.

The DeltaStream device has three horizontal axis turbines mounted on a common triangular frame.  This configuration provides a low center of gravity and structural stability so the device can sit on the seabed without the need for an anchoring system. 

TEL owns at least two international patent applications directed to its tidal power technology.  International Publication Nos. WO 2009/081162 (‘162 Application) and WO 2010/007342 (‘342 Application) are directed to the tidal power device’s framework and node structure and turbine assembly, respectively.

Figure 1 of each application is essentially the same and is reproduced below.  Both applications describe a freestanding structural frame assembly comprising steel tubes (2) and welded corner modules (3) interconnected by the tubes (2). 

Angled tube limbs (7, 8) extend from the corner modules (3), with each limb fixed to a respective nacelle tower (9).  Turbines (19) are mounted to each corner module (3) via a support shaft (20).

 

The frame assembly, which may have a triangular footprint, is held in position by its own mass and lack of buoyancy due to water flooding the tubes (2) and corner modules (3).  The tubes’ (2) proximity to the sea bed and the structure’s large base area relative to height provide additional stability.

According to the ‘342 Application, the turbine blade stagger angle and the choice of blade profiles are optimized so that the axial load on the turbine is kept in check, even at high rotational speeds. 

Other advantages TEL touts are the DeltaStream’s lightweight foundation, its lower cost of manufacture using many off the shelf components and the ease of maintenance, in particular because of quick replacement of the three nacelle modules.

Interestingly, the DeltaStream device marries two types of technologies:  according to TEL’s web site, it “uses the same concept as a wind turbine together with ship propeller technology.”

Pelamis Wave Power (Pelamis) is an Edinburgh, UK company that makes a snake-like device for generating energy from ocean waves.  Pelamis recently announced that it has secured an order for its P2 Wave Energy Converter from ScottishPower Renewables (see Recharge story here).

Pelamis’s P2 Wave Energy Converter (improved from the prior P1 model and rated at 750 kW) consists of several cylindrical sections connected by hinged joints, which move in ocean waves.  Hydraulic rams resist the motion of the joints and pump high pressure fluid through hydraulic motors, which drive generators to produce electricity. 

The generated power is fed through an “umbilical” cable to a junction on the seabed and then linked to shore.  Pelamis’s International Patent Application No. PCT/GB2009/050732 (‘732 Application), entitled “Marine connection system and method,” is directed to a system to facilitate faster connection between a marine structure and a sub-sea umbilical cable.

The connection system (1) comprises a buoyant winching system (2) having a winch (9) that can be towed to an off-shore location by a tug or other vessel.  Cable (3) is connected to cable (4) via a latching mechanism having a first element (5) and a second element (6). 

 

The second element (6) is permanently located at the connection site and is connected to a location buoy (32) using a tether line (26).  The buoyant winching system (2) may include a frame (7) mounted between two buoyancy units (8).  The winch (9) is carried on the frame (7) and has a reel (10) and a winch line (11).

A motor (12) is mounted on the frame (7) and may be mounted on the winch (9) for rotation and axial drive of the reel (10).  The line (11) is wound around the reel (10) such that it can be selectively paid out and wound in by rotation of the reel.

The ‘732 Application also discloses embodiments of the connection system used in conjunction with a marine structure “which comprises the first body to be connected to the second body,” which I read to be Pelamis’s sectional Wave Energy Converter.