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Green Energy Now, And On The Tide
thpr writes "The Electric Power Research Institute and its partners have completed their Offshore Wave Power Feasibility Demonstration Project, which defined potential wave energy projects off the shores of the United States. This is building off of work already done in Scotland (and elsewhere). San Francisco, New York and other areas are considering trial installations of the technology. It is interesting to note (table 1 in the report) that the energy density (kW/m^2) that can be achieved is much higher than wind or solar. In addition, harnessing 24% of available wave energy near the US at 50% efficiency is equal to all of the hydropower currently generated in the US (~7% of total electricity production). On a separate note, in the Office of Energy Efficiency and Renewable Energy's $1.2B 2006 budget the Department of Energy is closing out the Hydropower Technologies Program. Maybe that's why this technology is missing from our National Energy Policy?" Until it reaches maturity, though, U.S. readers can pay for other forms of green energy.
Yes, tidal forces DO cause the earth's rotation to slow down.
The tidal forces created by the earth on the moon have slowed the rotation of the moon down to the point that we only see one side of the moon. That is, the moon rotates about once a month. Similarly, the tidal forces of the moon are slowing the earth's rotation down, and it will eventually reach one about one rotation per month also. Assuming that the sun doesn't become a red giant first. And, speaking of the sun, there is also a tidal force that from the sun that will eventually cause the earth to rotate once per year. I'm not sure who this conflict between the moon's and the sun's tidal forces work out.
Conservation of angular momentum means that the tidal forces are causing the moon to orbit the earth faster, and thus further away.
While all these tidal forces are very small and only add up over very long periods of time, they can be measured. In particular, things like variations of the amount of snow on mountains, the amount of water in man-made lakes, the force of huricanes, and variations in the shape of the earth caused by earthquakes all add up to enough to cause the need for leap seconds.
Leap years keep the seasons from rotating through the calendar. Leap seconds keep the zenith of the sun ("noon") from rotating through the day. I forget the exact value, but there is something like an accumulated 20-30 seconds difference caused by these forces over the last 50 years, and therefore there have been 20-30 leap seconds added since then.
SPF support for most open source mail servers can be found at libspf2.
For those who want more, the best links on for intelligent green reading:
WorldChanging.com -- which also has an article about wave power.
TreeHugger, which is already linked in the story.
Dave Pollard, which writes very insightfully about lots of things including environmental philosophy.
Green Car Congress, where you can get the best news about green mobility, cool cars & industrial developments.
IDFuel, which is more about design but covers some of the same ground as TreeHugger.com
FuelCellWorks for all the latest news about fuel cells.
Grist Magazine, for news and a touch of humor, plus lots of interviews.
Treehugger? Treehugger... Treehugger!
Waves are cool, but don't forget ... OTEC (Ocean Thermal Energy Conversion)
My father was a primary designer on this, so I had the "real scoop" on what was going on there in real time, it was real exciting stuff back then!
Mini-OTEC, 1979
In 1979, the first successful at-sea, closed-cycle OTEC operation in the world was conducted aboard the Mini-OTEC, a converted Navy barge operating in waters off Keahole Point.
This plant operated for three months, from August-October 1979, and generated approximately 50 kilowatts of gross power with net power ranging from 10-17 kilowatts.
Its turbine generator produced a gross output of up to 55 kW. About 40 kW were required to pump up 2,700 gallons/min of 42F water from 2200-ft depth through a 24-in diameter polyethylene pipe and an additional 2,700 gallons/min of 79F surface water, leaving a maximum net power output of 15 kW.
This was a joint effort by the State of Hawaii and a private industrial partner.
More linkage: NREL's OTEC site
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