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Huge amounts of “free,” renewable energy are found in, on, and above the oceans of this world. Inevitably, that energy will be tapped as fossil fuels become scarcer and their use is seen to be incompatible with a sustainable environment for humans and other species of life. Even now, offshore wind farms are being installed in waters all over the globe (1).
Experiments using turbines on floating platforms are being conducted in several places – especially places where favorable winds are found but where the ocean is too deep to allow construction of wind-turbines that are attached to the sea floor (2). One very promising location for floating platforms would be in the area east of where Google is financing construction of transmission lines in the Atlantic Ocean. Those transmission lines will serve large offshore wind farms that will be constructed in shallow waters along the East Coast of the U. S. (3). There is no reason why those same transmission lines should not extend into deeper water to service wind farms on floating platforms.
In several prior posts (see references 4, 5, 6, and 7, below) I wrote about an “Energy Island,” an invention that could serve as one solution to global warming. The invention was recently awarded a patent by the U. S. Patent and Trademark Office. The patent, dated January 17, 2012, can be seen at the USPTO.gov website (8).
Energy Island is a floating platform that accommodates generation of electricity from multiple renewable sources of energy. Wind and water turbines and generators are used to produce electricity by capturing energy from air and water currents. Electricity is also generated from waves, differences in temperature between layers of water, and solar radiation.
On Energy Island, I specified installation of vertical-axis wind turbines because they would be easier to mount and maintain than the very tall conventional horizontal-axis wind turbines that are popular on land-based wind farms. That was a fortuitous choice because of a very promising development that has occurred in research on wind-farms that employ vertical-axis turbines. Research findings have shown an amazing ten-fold advantage in per-surface-area generation of electricity when closely grouped vertical-axis turbines are used instead of conventional horizontal-axis turbines, which cannot be closely grouped.
The following report was published in the Journal of Renewable and Sustainable Energy (9) after my patent application was submitted: "Potential order-of-magnitude enhancement of wind farm power density via counter-rotating vertical-axis wind turbine arrays." Caltech researcher John O. Dabiri found that a vertical-axis turbine would not lose efficiency when closely paired with another turbine that turned in counter-rotation. Furthermore, pairs of matched counter-rotating turbines could be arrayed on a wind-farm in relatively close proximity without appreciable loss of efficiency. That is not at all true for horizontal-axis turbines.
This is important. If Dabiri’s results are accurate, vertical-axis turbines will become the design of choice for wind farms that are located on either land or sea. Beyond their better efficiency in collecting energy from any given area, they have other advantages over horizontal-axis turbines: They are quieter, less a threat to birds and bats, less visually obtrusive, and less expensive to construct, mount and maintain.
With respect to Energy Island, Dabiri’s findings mean that a floating, platform-based offshore wind farm like Energy Island, using tightly grouped vertical-axis turbines, would almost assuredly be competitive in cost per kilowatt when compared with existing offshore wind farms -- farms where horizontal-axis turbines are mounted individually on very expensive-to-construct foundations that are built on the sea floor. If a floating platform were to employ multiple other sources of renewable energy (beyond wind) to generate electricity, as is specified in my patent, then it is likely that the Energy Island invention would be found to be a most cost-efficient way to tap offshore sources of renewable energy.
Environmentally aware people hope the U. S. and other countries will soon take action to stop global warming. It may be that Energy Islands – floating platforms that efficiently tap multiple sources of renewable energy -- will be found to be a cost-efficient way to fulfill that hope.
Thomas Manaugh, PhD
References
1. “Lists of Offshore Wind Farms by Country” by Wikipedia, retrieved from the Internet, January 31, 2012, athttp://en.wikipedia.org/wiki/Lists_of_offshore_wind_farms_by_country
2. “Floating wind turbine” by Wikipedia, retrieved from the Internet, January 31, 2012, athttp://en.wikipedia.org/wiki/Floating_wind_turbine
3. “Google Backs Offshore Wind Farm Backbone” by Katie Fehrenbacher, Oct. 12, 2010, retrieved from the Internet, January 31, 2012, at http://www.gigaom.com/cleantech/google-backs-offshore-wind-farm-backbone/
4. “A Solution to the Problem of Global Warming”
by Thomas Manaugh, retrieved from the Internet, January 31, 2012, at https://www.dolphinblue.com/pg-Global-Warming-Solution-Manaugh.html
5, “Oil Spill Disaster is Act One of Two-Act Tragedy”
by Thomas Manaugh, retrieved from the Internet, January 31, 2012, at
http://dolphinblueinc.wordpress.com/2010/05/17/oil-spill-disaster-is-act-one-of-two-act-tragedy/
6. “New Developments in Clean Energy Technology”
by Thomas Manaugh, retrieved from the Internet, January 31, 2012, at
http://dolphinblueinc.wordpress.com/2010/03/02/new-developments-in-clean-energy-technology/
7. “Proposed Effort to Slow Melting of Glacier in Antarctica”
by Thomas Manaugh, retrieved from the Internet, January 31, 2012, at
http://dolphinblueinc.wordpress.com/2009/09/23/proposed-effort-to-slow-melting-of-glacier-in-antarctica/
8. “System for Generating Electricity from Alternative Energy Sources Located on a Floating Platform” by Thomas Manaugh, retrieved from the Internet, January 31, 2012, at http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=manaugh.INNM.&OS=IN/manaugh&RS=IN/manaugh
9. “Potential Order-of-Magnitude Enhancement of Wind Farm Power Density via Counter-Rotating Vertical-Axis Wind Turbine Arrays” by John O, Dabiri, in Journal of Renewable and Sustainable Energy / Volume 3 / Issue 4, retrieved from the Internet, January 31, 2012, at http://jrse.aip.org/resource/1/jrsebh/v3/i4/p043104_s1?view=fulltext