Counter-spinning turbine design draws double the energy from ocean waves:
One of the more common approaches to harnessing wave energy is known as a point absorber buoy, which consists of a flotation device on the surface that is tethered to the seabed. As the buoy moves up and down with the passing waves, it drives an energy converter mechanism built onto the tether partway below the surface. This might be a geared drivetrain that uses the linear motion to spin a flywheel and generate power, as seen in some experimental designs.
The RMIT scientists used the point absorber buoy as a jumping off point for their novel generator, which they say addresses a couple of problems with conventional designs. To efficiently harvest energy, point absorber buoys typically need to use sensors, actuators and other electronics to precisely synchronize themselves with the incoming waves, but this leaves them open to maintenance and reliability issues.
In what they call a world-first design, the scientists eschewed all these synchronization sensors and electronics and went with a passive approach that has the device float up and down naturally with the swell. Two turbine wheels that are stacked close together down below rotate in opposite directions, and combine to amplify the energy being relayed to the generator.
This generator is housed inside a buoy above the surface to protect it from corrosion, and is connected to the spinning turbines via shafts and a belt-pulley drive transmission. Testing of this prototype in the lab showed that it could draw twice as much power from ocean waves as other point absorber designs, while promising a simpler and cost-effective path forward.
[...] Source: RMIT
Journal Reference:
Han Xiao, Zhenwei Liu, Ran Zhang, et al. Study of a novel rotational speed amplified dual turbine wheel wave energy converter, Applied Energy (DOI: 10.1016/j.apenergy.2021.117423)
from the motion-of-the-ocean dept
(Score: 3, Informative) by Anonymous Coward on Thursday August 19 2021, @11:16AM (7 children)
I tried to get some sense out of the linked article (https://newatlas.com/energy/counter-spinning-twin-turbine-generator-ocean-waves/ [newatlas.com]) but it had excluded the most important information: One turbine drives the rotor of the generator while the other drives the "stator" (in this case more like counter-rotor). This makes the relative rotational speed of the two parts twice as fast as keeping the stator static and just rotating the rotor while at the same time making the contraption fairly simple.
(Score: 2) by c0lo on Thursday August 19 2021, @11:43AM (6 children)
You may gain some efficiency, but ain't gonna double it.
https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Interesting) by FatPhil on Thursday August 19 2021, @01:08PM (5 children)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by c0lo on Thursday August 19 2021, @01:33PM (4 children)
If you get to extract quite a little from the total energy, i.e. your efficiency is low to begin with, you are right.
And, following the advice in the title of the thread, this looks to be the case.
https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Thursday August 19 2021, @11:36PM (1 child)
That's still quite a gain
(Score: 2) by c0lo on Friday August 20 2021, @02:37AM
Do you think that adding two more rotors will double it again?
https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Friday August 20 2021, @01:51PM (1 child)
When you don't have to pay for the fuel, low efficiency isn't a deal breaker.
(Score: 2) by c0lo on Friday August 20 2021, @02:02PM
If you don't mind paying the maintenance of the engine more that the benefit you get from the engine's work, fuel efficiency isn't indeed a concern.
https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by BsAtHome on Thursday August 19 2021, @01:18PM (5 children)
Water is very dense stuff. Much more difficult to handle than air and even air is a challenge. More so, salt water is very corrosive and the stresses generated are extremely high.
There have been many concepts and tests harvesting wave energy and none has proven effective over long periods. The maintenance and failure rate in the extreme environment makes it not profitable (enough) in the real world.
(Score: 0) by Anonymous Coward on Thursday August 19 2021, @02:17PM (4 children)
You are correct. If you want to stick to purely "green" electricity generation, wind turbines are probably a better bet.
(Score: 2) by DannyB on Thursday August 19 2021, @03:46PM (3 children)
Winds may not always want to blow. Sometimes there are places where the sun don't shine. Waves always want to wave.
Fact: We get heavier as we age due to more information in our heads. When no more will fit it accumulates as fat.
(Score: 3, Interesting) by ls671 on Thursday August 19 2021, @04:25PM (2 children)
Where I live, when there is no wind, there is no wave :(
Everything I write is lies, including this sentence.
(Score: 2) by bmimatt on Thursday August 19 2021, @07:12PM (1 child)
There are places where high waves and strong rip currents are a thing. Constantly. Seems like a prime place to deploy some of these turbines.
(Score: 2) by Reziac on Friday August 20 2021, @04:24AM
I'd think low-key but steady would be both more reliable, and tear up less equipment.
And there is no Alkibiades to come back and save us from ourselves.