Harnessing Slow Water Currents For Renewable Energy 113
Julie188 writes "Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer, Michael Bernitsas, has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power. This is is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2.3 miles per hour). Most of the Earth's currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently. Further details and a few brief movies of the technology are available, as well as a video explanation by Professor Bernitsas himself."
Re:Secondary effects? (Score:4, Informative)
Water runs down hill due to gravity, once it is passed the device
it will return to its prior speed.
The water does not get and keep its speed from its headwaters.
It varies based on the grade as it moves downstream.
In an ocean, it is not due to grades is more about thermal
differential due to the ocean heating the water.
It might have an impact there, but some of the current
contain flows that are many times the flow of all the rivers
in the world.
Like the Antarctic Circumpolar current:
http://en.wikipedia.org/wiki/Antarctic_Circumpolar_Current [wikipedia.org]
Re:Doubling the Global Warming Reduction (Score:3, Informative)
hmm except that I'm reading it now and it says Interesting... so I'd say the moderation system works just fine - only not on a short timeline. It's like looking at an election vote too early... maybe only the no votes happened to be counted first... doesn't mean the voted on item won't pass later.
Re:Oceans, Not Rivers (Score:3, Informative)
That may be the case where you live but here in the the western U.S., the majority of dams have been built for water storage purposes, followed in number by dams built for generation of hydropower. Relatively few have been built exclusively for flood control; I can think of a couple in the Los Angeles area and that's about it.
Re:Secondary effects? (Score:2, Informative)
So you are not harvesting energy that would be lost energy; you are harvesting the energy of the flow.
Re:Secondary effects? (Score:3, Informative)
The Colorado River at Phantom Ranch averages 80,000 ft3 of water per second, or 2.4 x 10^9 cc. The energy that would have to be extracted to cool that water by 0.001 degrees C would be 2.4 x 10^6 calories.
2.4 x 10^6 calories = 10^9 joules.
watts = joules/second, so that would be 10^9 watts, or 1 million kilowatts/second would be extracted. Now that's a lot of power for a 1/1000 degree temperature drop.
Another way to look at it is that it would take a million kilowatts to heat 80,000 ft3 of water 0.001 degree C.
We can be pretty darned sure that nowhere near that amount of power would be extracted by these vortex generators, so it is not reasonable to assume that the cooling of water from the extraction of energy using this method could possibly be an environmental hazard to anything. The energy extracted from the moving water would equal to millionths or billionths of a degree.