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, Insightful)
Re:Secondary effects? (Score:2, Insightful)
From the look of the system, there wouldn't appear to be too much slow down. Probably about on par with tossing a reasonably sized rock into a stream.
Of course, it's a matter of scale. One rock? not much impact, but throw to many in, and you have a dam. So I think the impact this system would have depends most on how much power it generates and how many can be fit on a given body of water before having a damming effect.
Oceans, Not Rivers (Score:5, Insightful)
This device targets ocean currents, not rivers. Ocean currents already have too much energy (by historical comparison), accumulated in twistier undersea currents from the decades and centuries of escalating Greenhouse effects.
River current power is what is captured by hydroelectric dams. Which have their own problems, but we're already stuck with them. More ocean hydroelectric could allow us to release some dams that have too high a cost (environmentally or operationally) to justify their power output. Though application of these generators in rivers might just be a low-impact replacement for dams. However, the dams also deliver irrigation and drinking water, so we're probably stuck with them for the long haul.
Re:That acronym is so 1980's... (Score:5, Insightful)
No. No. No. Scientists, and anyone, should name things what they want, and Google should make a considerably higher effort to make search work MUCH better than it currently does. This just shows you how bad search is, and far it has to go. Google needs more competition.
Re:Secondary effects? (Score:3, Insightful)
Re:Secondary effects? (Score:3, Insightful)
"A damming effect" would never be a problem, the slower the water is moving the less energy available for extraction, so you would stop installing them long before the water stopped moving. I would guess that capital return rates would convince investors to stop installing them long before environmental impact became a significant problem.
Harnessing the power in every flush (Score:1, Insightful)
Why not put these things in the city sewage pipes and harness the power of the flush
Re:Oceans, Not Rivers (Score:3, Insightful)
while you're probably right in that this technology will be most useful by extracting the vast amounts of energy contained in the ocean (absorbed solar energy) it will likely be deployed in a lot of rivers as well. in fact, the video mentions that the pilot project is being built on the Detroit River. so it's not just coastal cities who are going to benefit from this technology.
i think it's interesting that this technology is expected to be much more cost-effective than conventional solar power. and the ability to operate efficiently in rivers too slow for hydroelectric dams is another plus. rather than simply being a low-impact replacement for dams, it's more likely that this technology will open up hydroelectric power in a lot of new places with slow-moving currents where hydroelectric dams can't be used.
Re:That acronym is so 1980's... (Score:3, Insightful)
Hey I agree with you. I've been trying to get someone to do a weighted search for a long time... no takers... I'll have to do it myself. Works like so:
Put in two words... tell the search engine that the second word is WAY more important, ie: Bass (+0) + Fish (+10)
What you should get back is a whole lot of pages about Fish where Bass is the actual keyword within that subset. Almost works like a category. Really it's multiple searches... first a search for the highest rated keyword, then a second search within those results for the next highest rated, and so on until you get to the lowest rated keyword.
The ideal UI would be to use sliders for each keyword and use an AJAX call to update your results live. This way you could play with the numbers and see immediate results. Then you bookmark it.
Re:Secondary effects? (Score:3, Insightful)
Are we all forgetting what caused the water to move in the first place? I mean the last couple of comments sort of act like this is a car on flat land coasting and we are talking about hitting the brakes every once in a while or introducing obstacles to slow it down. Imagine the same but with the car constantly coasting down hill.
Gravity is forcing the waters motion. It is going from one place that is higher to another that is lower in elevation. You have other factors like force and so on to consider but slowing the water down at a specific point would only be a temporary effect that would eventually rejoin the force of gravity and the weight of all the water behind it. Unless you damn the entire river up, your not going to be able to take enough energy out of the system to cause a lasting effect. This is because the momentum and force behind the water will just cause what is moving too fast to penetrate the blockage as efficiently to raise up and over it causing gravity to take hold in original ways again. This is different then say water in a pipe that has no other place to go.
Look at the spill ways of reservoirs. They line them with concrete spikes and riffraff to control the erosion but the water going into it is still effected by gravity and moves down hill as it normally would. The water will move around the objects or rise over them and create a controlled turbulence but it doesn't stop it. Try this experiment. Take a bowl, turn it upside down, place it in a cake pan or something else to capture the water and pour a glass of water slowly on top of it. Time how long it takes to fall off the bowl. Now have a friend put his fingers all around the bowl as to block portions of it, now poor the water in the same way and it will evacuate just as fast.
The only real difference between a fast moving river and a slow on is the drop in elevation from the height of the water at the beginning to the end and the carrying capacity of the channel. These generators will basically lower the carrying capacity causing a larger drop in elevation from the top of the water where they are installed to where the river will dump out in.