Energy

"Telescoping can" wave energy device beats test predictions by 20%

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The Archimedes Waveswing prototype has been installed for testing over the last 6 months, and is delivering better results than expected
AWS Ocean Energy
The Archimedes Waveswing prototype has been installed for testing over the last 6 months, and is delivering better results than expected
AWS Ocean Energy
The 50-ton prototype makes quite a sight on the road
AWS Ocean Energy
The AWS device is quick to deploy, going from the dock to fully operational in some 12 hours
AWS Ocean Energy
While the prototype is rated at a fairly uninspiring 16 kW, AWS says commercial units will be rated at up to half a gigawatt
AWS Ocean Energy
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Scotland's AWS Energy has reported results some 20% better than predicted for its Archimedes Waveswing, a prototype wave energy generator that's been undergoing ocean-based testing at the European Marine Energy Centre (EMEC) in Orkney for the last six months.

The Waveswing is a cylindrical metal buoy that's tethered to a single point on the ocean floor. In operation, it stays beneath the surface and responds to water pressure changes. As a wave passes overhead, the pressure increase pushes down on the top "floater" section of the device, sliding it downward relative to the lower "silo" section, with a rolling seal ensuring no water gets in.

This linear motion in this "telescoping can" compresses the air in the Waveswing device, creating an air spring to push the floater section back up as the wave rolls onward. As the floater moves up and down, it drives a hydraulic motor, which converts the linear motion into rotation, and a regular electrical generator draws power from both the upward and downward strokes.

The device can be raised and lowered on its tether for maintenance and deployment, and there's also a facility to regulate the air pressure inside the cylinder, effectively tuning the air spring to take maximal advantage of the wave conditions.

AWS reports that "during a period of moderate wave conditions" at the EMEC installation, the prototype machine captured an average of 10 kW, with peaks up to 80 kW, against its rated capacity of 16 kW. The test has also demonstrated that the Waveswing can be fully deployed from sitting quayside to fully operational in less than 12 hours, and that it can survive Force-10 gale conditions.

The power output frankly looks surprisingly low to us given the size of this machine. It stands a towering 7 m (23.0 ft) tall fully extended, with a diameter of 4 m (13.1 ft), and it weighs 50 tons; it makes a pretty impressive sight as it's driven down the road on a trailer.

The 50-ton prototype makes quite a sight on the road
AWS Ocean Energy

But this is not the commercial device. AWS says these units will be configurable for power ratings between 15 kW and 500 kW – although it's unclear whether these half-megawatt versions will need to be physically bigger, or if so, by how much. The company sees commercial deployments taking the shape of multi-absorber structures, which could see 20 of the most powerful units arrayed together into a 10-MW platform.

According to IRENA, there's enough energy in the motion of the ocean – specifically, in wave energy as opposed to tidal energy – to meet the world's entire energy demand. But the technology here is in its infancy; there are plenty of pilots and prototypes, but precious few commercial installations. And since nothing has proven itself yet, there's a fascinating proliferation of different designs all duking it out in search of a solution that's cheap, easy to deploy and maintain, eco-friendly, and capable of producing power in all sorts of conditions for decades despite the brutal corrosive assault of salty seawater and sludgy biofouling.

Effectively harnessing wave energy could radically lower prices of renewable energy grids; these things won't shut down at night like solar, or when the wind drops, so they can reduce the need for long- and short-term energy storage that a grid needs to guarantee a reliable electricity supply. This, as CSIRO modeling for Wave Swell Energy's UniWave generation systems suggests, could slash up-front CAPEX (Capital expenditure) on multi-mode renewable energy systems by as much as two thirds.

So it's an area of immense potential and consequence, but also one where it seems we'll need to keep being patient. See the Waveswing prototype operating in the video below.

Source AWS Ocean Energy

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12 comments
Pupp1
When an industry is still considered to be in its infancy after half a century, you sort of have doubts it will ever grow up. Though, perhaps one day, the right person will come up with a true technology breakthrough, and it not just be another opportunity to get a grant.
WONKY KLERKY
Best tell HM's Coastal Command before a minesweeper spots one.
kwalispecial
If you had enough of these pulling energy from the waves, there'd be less energy left in the water. Perhaps a wave energy farm could be strategically located in a place where you also want to reduce coastal erosion, and kill two birds with one stone.
freddotu
I'm surprised the energy transmission system is based on hydraulics. Hydraulic systems are notoriously inefficient, which is one reason hydraulic power systems for bicycles are non-existent. One might think a linear generator design would provide for direct energy capture, unless there are other design constraints involved.
jayedwin98020
1) What is the projected cost per kW, and how does this compare to the current costs of electricity being generated via "dam power" generation?

2) If saltwater corrosion is a foreseeable problem, why not make the shell, and any components that come in contact with seawater, from a non-corrosive material?

3) When all is said and done, what is the ROI, and what is the time frame to achieve the ROI, vs. longevity, or life expectance, of a unit?

4) What is the projected longevity of a commercial unit?

5) Will there be an ongoing "maintenance component" that will be required per each unit?
TechGazer
Seems like high mechanical wear potential, compared to the blowhole type.
BlueOak
“The power output frankly looks surprisingly low to us given the size of this machine.”

Exactly the type of constructive rational cynicism we have come to expect from New Atlas and in particular, Loz!

One wonders about boating and shipping collision since this device appears to need to ride just below the surface?

And have they tested a non-hydraulic mechanical energy conversion system to eliminate the hydraulic inefficiencies? Seems like the simplicity wound be a cost and reliability advantage as well as improving efficiency.
vince
Uildup of missels and other biologogical organisms that slowly melt ships like titanic will probably make these a bad idea.
christopher
@BlueOak - Loz is bang-on the money: 10kw is utterly absurd. This thing weighs *50tons* - to put that into perspective, the raw price of steel is the same per 1-ton as a 10kw solar system, so including other costs, maintenance, lifespan, etc etc - this WAY MORE than *100 times* more expensive than a solar+battery system. Or another way to look at it - this delivers *200 times* less electricity than a modern wind turbine of the same price, with wind turbines lasting 2 to 10 times longer and needing 10 times less maintenance.
Nikola Paulson
"there's also a facility to regulate the air pressure inside the cylinder" - why rely on the excessive amount of maintenance required to remove the cylinder to a facility when the O2 can be provided through hydrolysis? Nuclear subs have been using hydrolysis for decades now, the technology is there.. why not integrate it? The maintenance schedule for a hydrolytic converter is much more inside the realm of practicality than manually adjusting air pressure via cylinder swap for every change in weather.