Aquamarine Power is a Scottish wave energy developer that recently completed a first round of fundraising (10 million British pounds) and deployed a full scale demonstration model of its Oyster wave energy converter.

International Application No. PCT/GB2006/000906 and the corresponding U.S. Patent Application Pub. No. 2008/0191485 (‘485 Application) describe the Oyster.

The ‘485 Application is directed to a wave energy conversion device (1) comprising a base portion (2) anchored to the seabed (4).  A flap (8) is pivotally connected to the base portion (2) and moves back and forth in an oscillating motion in response to waves (7).

 

Deflector plates (13, 70) direct waves onto the flap (8), thereby improving power capture.  According to the ‘485 Application, curved end sections (78) also improve power capture. 

 

When the flap (8) oscillates in response to wave action, driving rods (66) cause hydraulic fluid in cylinders (68) to be pressurized by the action of pistons (not shown).  The pressurized fluid is delivered to on onshore turbine that generates electricity.

According to this Matter Network story Aquamarine Power has an agreement with Scottish and Southern Energy to develop up to 1,000 megwatts of marine energy sites by 2020 using the Oyster technology.

 

Last month Google.org announced investment of over $10 million in geothermal technology.  Specifically, the web search company’s investment arm will give $6.25 million to Sausalito California-based geothermal company AltaRock Energy (AltaRock), $4 million to Redwood City, California drilling technology company Potter Drilling (Potter) and almost $500,000 to the Southern Methodist University Geothermal Lab (SMU) (see greentech media piece here)

Although the United States trails other countries in some renewable energy sectors such as solar, wind and biofuels, it is the world leader in geothermal energy.

The particular technology Google.org is funding is EGS, or enhanced geothermal systems, which involve drilling deep holes into hot rock in two locations and injecting water into the cracks in the first location.  Steam pressure forces the resulting super-heated water up through the holes in the second location, and that heat is used to run a turbine and produce electricity.

According to AltaRock’s web site, the company owns a portfolio of EGS patent applications and holds exclusive licenses for related intellectual property.  However, searches of the U.S. Patent & Trademark Office database for AltaRock as assignee yielded no results, and AltaRock did not respond to an e-mail inquiry about its patent portfolio.  A similar search for SMU also came up empty.

The good news for AltaRock continued this month as it reached a deal with building products and real estate firm Weyerhauser Company to develop geothermal projects in northern California, Oregon and Washington.

 

Potter owns a patent application directed to drilling systems and methods for geothermal heat pump applications.  U.S. Patent Application Pub. No. 2008/0093125 (‘125 application) describes a method for creating more stable bore holes by making the holes non-circular.

According to the ‘125 application, elliptical, oval or eccentric shaped holes prevent portions of the rock formation from breaking apart from the bore hole wall.  Non-circular bore holes also facilitate installation of piping for heat pumps and provide improved geometry for heat exchange.

In addition to funding clean technologies, Google is developing its own.  Last month Google Inc.’s U.S. Patent Applicaton Pub. No. 2008/0209234 (‘234 application) published. 

The ‘234 application describes a floating platform-mounted computer data center with an electrical generator and cooling units.  The data center of the ‘234 application gets its electricity from wave power and is cooled by the sea water upon which it floats.

For me at least, the clean technologies are rife with problems of nomenclature and categorization.  I didn’t realize until I read this Green Tech Gazette piece that water power had so many subcategories.  The article sums it up nicely:

Hydropower is generated from dams . . . . Current power is generated from rivers and streams . . . . Tidal power uses the predictable flow of the tides to generate electricity around the ocean shores. And, ocean power . . . involves water turbines that are offshore and a bit farther out to sea than the tidal devices.

In view of these definitions, yesterday’s post should have opened with a reference to “water power” instead of the more limiting “wave power.”  It also probably should have specified that Marine Current Turbines’ technology harnesses tidal power, and Verdant Power’s turbines are designed primarily for current power. 

I’ve also changed my water category heading from “Hydropower” to the broader and more inclusive “Water Power.”

There has a been a lot of activity in wave power recently, with the world’s first commercial tidal energy turbine installation completed in Northern Ireland last week, another project being developed in the Ontario River near Cornwall, Canada, and possible expansion of a small installation in New York City.  The technology for the Ireland project was developed by British firm Marine Current Turbines, and the NYC and Canada installations were designed by Verdant Power, a New York-based company (read the Matter Network stories on Ireland here and Canada here).

Water turbines operate in much the same way as wind turbines, but the greater density of water presents somewhat different technological challenges.  The increased density of water means that water turbine blades can function with smaller wingspans than air turbines.  However, the effects of drag and wake formation are greater in water and can cause a large thrust force on the turbine blades, interfering with the flow through the turbine rotor.  In addition, the flow rate varies significantly with the depth of the water.

Some of Marine Current Turbines’ patents seek to address these problems with their turbine installation designs.  U.S. Patent No. 7,331,762 is directed to a turbine support structure having the turbine rotors situated between two parallel decks.  The upper and lower deck each have a different streamlined cross-section, with one being more convex than the other.  This design accelerates the flow of water over the more convex surface to eliminate the difference in flow rates between the upper and lower water streams, thereby reducing interference with the rotor.  

U.S. Patent No.7,307,356 (‘356 patent) covers a bifurcated column design having a vertical gap designed to support twin turbine blades.  The two blades spin in opposite directions to operate in bi-directional water flows (i.e., both ebb and flood tides).  This setup also is beneficial because the two rotors offset each other’s torque.  A horizontal turbine support structure extends perpendicular to the column with a portion extending through the vertical gap.  This design minimizes water drag and wake formation so the bi-directional water flow doesn’t interfere with the rotor.  The technology deployed in Northern Ireland, Marine Current Turbines’ SeaGen, appears to be an embodiment of the ‘356 patent. 

Verdant Power’s patent application Pub. No. 2007/0063520 is directed to a system for generating power from slow moving water flows for use in non-tidal flowing water such as man-made canals or aqueducts.  The system consists of a water flow flume with a network of slopes and curves, including an acceleration zone to increase flow velocity and create kinetic energy from water movement. 

Looks like this is just the beginning for commercial tidal power installations and for Marine Current Turbines in particular, which has other projects slated for the next few years, including in Vancouver and Wales.