Harnessing the awesome power of the ocean waves

May 14, 2012
Schematic illustration of MBARI's wave-power buoy. Place your cursor on the image to see the buoy in action. Image: Kim Fulton-Bennett. Credit: 2012 MBARI

MBARI engineer Andy Hamilton looks out his office window in Moss Landing and points at the waves crashing on the beach below. “Pretty impressive, aren’t they? You’d think there’d be a way to make use of all that energy.” Since 2009, Hamilton has led a team of engineers trying to do just that. Their goal is not to replace the hulking power plant that overlooks Moss Landing Harbor, but to provide a more generous supply of electricity for oceanographic instruments in Monterey Bay.

Hamilton’s “power buoy” project is funded by the Defense Advanced Research Projects Agency (DARPA), which sponsors research into revolutionary new technologies that might one day be used by the U.S. military. The project started with a three-month grant to assess the availability of wave power around the world, and to assess DARPA’s previous attempts to generating electrical power from the .

Hamilton’s initial research and calculations showed that DARPA’s previous efforts had been too timid—their small prototype buoys were never able to take advantage of the full energy of the waves. So Hamilton proposed to "go big" (but not as big as commercial wave-power projects).

He spent another nine months using computer models to test different buoy designs under a variety of simulated wave conditions. In the end, he came up with a buoy that was 2.5 meters (8 feet) across. Hanging in the water below this buoy is a massive metal plate 3 meters (10 feet) wide and 5.5 meters (18 feet) long.

Because most wave motion occurs at the sea surface, the buoy rises and falls with the waves, but the plate, 30 meters (100 feet) down, remains relatively stationary. Between the surface buoy and the metal plate is a large hydraulic cylinder with a piston inside. As the buoy rises and falls, it pushes and pulls on this piston. This forces hydraulic fluid through a hydraulic motor, which in turn runs an electrical generator.

Engineering in the real world

This sounds simple in concept, but as is often the case, things become much trickier when you try to build a real device that will work in the real ocean. Fortunately, Hamilton recruited a team of resourceful engineers to work on the project. Mechanical engineer François Cazenave has worked full time on this project for the past 18 months. Other team members include mechanical engineer Jon Erickson, electrical engineer Paul McGill, and software Wayne Radochonski.

One of the first challenges the team faced was figuring out the best way to convert the vertical motion of the waves into rotary motion that could power a generator. First they bought a custom-made generator from an outside company, but that turned out to be too inefficient to be useful. Going back to the drawing board, the team designed their own system using an off-the-shelf hydraulic motor similar to those used on earth-moving equipment and on MBARI’s underwater robots. These hydraulic motors use moving hydraulic fluid to drive a rotating shaft with up to 95 percent efficiency.

Another challenge that Hamilton's team faced was designing a mechanism that would return the piston to its starting point after a wave had passed. Hamilton initially envisioned using a large metal spring for this purpose, but the metal spring turned out to be much too heavy. So the team redesigned the system to incorporate a pneumatic spring—a chamber filled with nitrogen gas, and mounted at one end of the piston. As the piston moves with the waves, it compresses or decompresses the nitrogen gas in the chamber. After the wave passes, the gas in the chamber returns to its original pressure, forcing the piston back to the middle of its stroke.

Mechanical technician John Ferreira prepares the power buoy for a deployment in MBARI's high bay. At this stage in the design process, the hydraulic piston was enclosed in a cylindrical housing of yellow foam (at lower left). Image: François Cazenave. Credit: 2011 MBARI

In yet another challenge, during the first field trials of the new piston, the cable attached to the metal plate swung from side to side, damaging the seals of the hydraulic cylinder and causing it to leak. The team added a long metal tube as a guide to make sure that the cable pulled in line with the axis of the piston. In a later deployment, metal shards in the hydraulic fluid caused additional damage. Eventually the engineers rebult the system, adding a fluid reservoir/pressure compensator and an in-line filter to keep the hydraulic fluid clean.

Over the past year, the power buoy has been deployed in Monterey Bay about half a dozen times. With each deployment, the team added new features and refinements. By late 2011, the buoy was generating up to 400 watts of power, more than twice what MBARI’s existing moorings can produce using wind generators and solar panels. Hamilton says, “Remarkably, the system is behaving very similar to our models. We were aiming to produce about 500 watts of power, so we’ve almost hit our target.”

The next challenge: making useable electricity

Although we tend to think of the open-ocean waves as long, gentle rollers, anyone who has been at sea knows that wave motion is often erratic and unpredictable. So is the voltage produced by the generator on the power buoy. As each wave passes, the generator first speeds up, then slows down again, generating electricity at from 0 to 500 volts (AC).

In late spring of 2012, the team will test a new version of the system that incorporates power-conditioning hardware and software to change this fluctuating voltage into a steady 24 volts (DC) useable for scientific instruments. Initially, this current will be used to charge batteries on the buoy. Any excess current will be run through a series of resistors that dissipate the energy as heat.

During the upcoming deployment, the team will also test new hardware and software that could dramatically increase the efficiency of the power buoy. Surprisingly, this involves adding resistance to the system—essentially making the piston harder to push at certain times in the wave cycle.

The new software continuously and automatically changes the resistance of the system to adjust the load on the generator and optimize the speed at which the generator turns. If the generator is spinning too fast, the software increases the resistance of the system to generate more power. If the generator is moving too slowly, the software reduces the resistance of the system, allowing the generator to speed up.

MBARI engineers and technicians recover the power buoy during stormy sea conditions. On the right side of the image you can see the metal "plate," which has been hoisted up on the stern of the boat. Credit: Kim Fulton-Bennett © 2011 MBARI

The dream: an underwater charging station

As if the challenge of extracting energy from the waves wasn’t enough, the power buoy project includes another ambitious element—an underwater charging station for undersea robots. Autonomous underwater vehicles (AUVs) are undersea robots that are programmed at the surface and then travel beneath the waves, collecting information as they go. However, many AUVs can only run for a day or two before their batteries need to be recharged.

Working in tandem with Hamilton’s team, a group of MBARI engineers led by Jim Bellingham and Brett Hobson have been working on an underwater “docking station” that will eventually hang down beneath the power buoy. When an AUV senses that its batteries need charging, it will automatically home in on the docking station, plug itself in, download its data, recharge its batteries, then head out for its next mission. Hamilton says, “This is the ultimate dream for the power buoy. We’re working on the pieces of it now.”

So far, the AUV-docking team has built a non-powered docking system, and have been developing software for MBARI’s long-range AUV so that it can automatically find and park itself inside this “mock dock.” They are also working on the electronics for the actual charging dock. In field trials, the AUV has entered the “mock dock,” but cannot yet do this consistently.

The future of wave power

Hamilton’s development grant for the power buoy runs out in Fall 2012. By that time, he hopes to demonstrate the system’s usefulness and attract additional funding for the project. According to Hamilton, “A lot depends on finding a ‘science driver’—a specific science project that would benefit from this extra power we’re producing.” He adds, ”We’re not trying to compete with wind and solar generators. We’re complementing them. As with most renewable energy sources, it’s better to have some redundancy.”

Although big storm waves carry a lot of power, it turns out that the bulk of the wave energy in Monterey Bay is provided by moderate sized waves that occur relatively frequently. Cazenave explains, “The power buoy must be able to survive storm waves, but it is most efficient in the most common types of waves—say two meters high. There is more energy in bigger waves, which can reach four to five meters around here, but they are not so common.”

The vastness and changeability of the ocean will always hamper our efforts to understand this global environment. One of the key challenges for oceanographers over the next decade will be how to power complex instruments that remain in the open ocean for long periods of time. MBARI’s wave-power buoy is part of the solution to this problem.

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User comments : 39

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Vendicar_Decarian
3.4 / 5 (9) May 14, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.
dacarls
1 / 5 (1) May 14, 2012
Not to be overly picky, but the animation shows the "anchoring cable" stretching, with no movement seen at the bottom of the bouy
???
kaasinees
2.2 / 5 (13) May 14, 2012
@dacarls
MAGIC!!
Nope seriously look again closely :)
Jeddy_Mctedder
1.4 / 5 (18) May 14, 2012
Darpa is known for making mistakes lets just say this is one of their obvious ones.

Wave power is and has been proven to be useless.
You want to use ocean currents. ..go ahead ( as difficult as they are to harness there are good arguments to invest in submarine current turbines. )

Wave power is and always will be total shit. Imagine trying capture the wind only in the area 10 feet from the ground.......

Theres a eeason that useful harvesteable energy is not found at or near major boundary layers ----too much turbulence. You want a steady predicteable flow of energy. Like a dam or a windwill above the roof of a house.

Wave power?!? Just put some damn solar panels with vertical windmills....on them if you want a killowatt of power in the middle of the ocean. ...it would be WAY Cheaper to ' develop ' as most of the system would be bootsrapping off tge shelf systems onto a flotation raft.
Eric_B
4.2 / 5 (5) May 14, 2012
Vendi, what are you talking about?

My desktop has a 400 watt power supply...

I have a refrigerator, don't you?
GSwift7
1.8 / 5 (17) May 14, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently


It wouldn't even handle the power supply for my gaming computer when it's at full load. lol. (1200 watts capacity, but I only use about 650 at full test load) That doesn't include the monitor or speakers though.

I love DARPA. The DARPA funding model has produced so much cool stuff that nobody else would ever fund. Sometimes I wonder what they intend to use these things for though. The above system is a good example of a project where I have trouble imagining what the military appliction might be. Lots of cool sci-fi kinda stuff comes to mind, but who knows.

I wonder how the IP rights work in a case like this. Surely DoD owns the rights to the work, but the guy above is talking about continuing to work independently, if he can find funding.
Terriva
1.3 / 5 (14) May 14, 2012
Just another technology, which actually delays the research and implementation of cold fusion.

MIT Device Outputs 14 Times Input Power, Faces Funding Cut
antialias_physorg
3.5 / 5 (11) May 14, 2012
I have a refrigerator, don't you?

If your refrigerator is running more than a few minutes per hour then you should get a new one.

My desktop has a 400 watt power supply...

Unless you're playing high end computer games 24/7 you're only using a fraction of that.

When checking what type of electrical power you need you have to take average power use over the course of a 24 hour period. Running a washing machine or baking oven uses lots of power, but you're not doing it continually.

Just googled the numbers for germany and average use comes out to about 170 watt per person. (US is about double that. Numbers are without heating, though)
dschlink
1.7 / 5 (6) May 14, 2012
Anyone who actually read/comprehended the article would have seen that this is intended to replace wind and solar systems, which have proven to be unreliable and inadequate. Although large scale wave systems have never been able to achieve reliable operation, a smaller system can.

Terriva
1 / 5 (10) May 14, 2012
IMO this principle could provide the electricity for heaters and beacons at the personal lifeboats
CHollman82
2.3 / 5 (15) May 14, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


But you would use a hell of a lot more than that peak, you need to consider the peak capacity as well as the average.
sizemick
5 / 5 (2) May 14, 2012
The first step is to get the generator working as efficiently/reliably as possible -- a great engineering challenge almost completed. Next is to treat cost as an engineering challenge, bringing it down as much as possible.
Large areas of these devices, mid ocean, would be able to generate significant quantities of synthetic fuel which could be used to power conventional ships -- if they are looking for a use.
I'd like to see what would happen if they used different parameters to evolve a system that strives for simplicity, reliability, and low cost over all else, as opposed to efficiency.
Off hand, I can think of one way to make such a device using much of what they've learned already:
Use the same float and resistance plate, but instead of any internal workings in the float, place "sausage" links along the connecting rope. Each sealed link could be stretched a small amount, driving either a linear or rotary magnet. The links get cheap due to volume, and are redundantly reliable.
MCPtz
5 / 5 (4) May 14, 2012
A lot of posters here jumping the gun.

They're talking about a specific application for long range AUVs in the Monterey Bay. Robots would come dock at one of these to recharge. They're probably looking to find other very specific applications where consistency is not as important as having a locally available and deploy-able charging station.
NotParker
1.5 / 5 (21) May 14, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


And cost 15x more than your home.
NotParker
1.5 / 5 (24) May 14, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


But you would use a hell of a lot more than that peak, you need to consider the peak capacity as well as the average.


You have to consider backup power supplies for those beautiful windless days where the ocean is like glass ...
Estevan57
2.2 / 5 (26) May 14, 2012
This work is very similar to that done by Oregon State University in 2008.

antialias_physorg
3.6 / 5 (7) May 14, 2012
But you would use a hell of a lot more than that peak,

There are places where this hardly ever happens. And yes: as always with alternative energy sources we need to consider some form of energy storage to tide over the occasional day without much input or peak demand.

The more diverse our energy sources are (and the larger the grid is) the less such storage we'll need. The device in the article should be seen as one solution among many.

All the energy (solar, wind, wave) is a direct or indirect result of solar radiation (except geothermal and tidal). And the input of solar energy on the planet is fairly constant.
So if we become adept at tapping into that - whatever the weather conditions - then we could go without any storage at all.
javjav
2.5 / 5 (2) May 14, 2012
But you would use a hell of a lot more than that peak, you need to consider the peak capacity as well as the average.


That problem is perfectly solved with batteries, which are mentioned in the article.
MarkyMark
3.7 / 5 (3) May 15, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


But you would use a hell of a lot more than that peak, you need to consider the peak capacity as well as the average.


You have to consider backup power supplies for those beautiful windless days where the ocean is like glass ...

That is why there are multiple sources of Alternative Enery such as Solar. I dont see why they cant affix something to take advantage of this assuming its needed afterall glass oceans are soooo Common in seas like the Arctic
Vendicar_Decarian
4.3 / 5 (6) May 15, 2012
My rate of power consumption last month averaged 472 watts according to my electric bill.

And that is with a house guest who has increased total power consumption by about 20 percent by having a high power PC running constantly doing video rendering.

I flit between a 6 core AMD box and a duel core machine.

Cooking and hot water are electric.

"My desktop has a 400 watt power supply...
I have a refrigerator, don't you?" - EricB
CHollman82
1.4 / 5 (10) May 15, 2012
All the energy (solar, wind, wave) is a direct or indirect result of solar radiation (except geothermal and tidal).


Geothermal is an indirect result of stellar activity, and tidal is a very indirect result of the same, though not from our star.
Vendicar_Decarian
4.3 / 5 (6) May 15, 2012
God is creating those days as a holiday.

"You have to consider backup power supplies for those beautiful windless days where the ocean is like glass" - ParkerTard

Are you anti-God NumenTard?

Why do you insist on working against God's will?
Tachyon8491
1.8 / 5 (10) May 15, 2012
God is creating those days as a holiday.


Looking at all the F$%^& %$ @#$%^ in the world, god needs a better back-up power supply.
antialias_physorg
4.2 / 5 (5) May 15, 2012
Geothermal is an indirect result of stellar activity, and tidal is a very indirect result of the same, though not from our star.
Only if you wish to be exceedingly pedantic about it (and if we REALLY want to be pedantic aboutit that not teh case for all of it: Any primordial hydrogen, helium and lithium that contributes to the pressure which keeps the mantle liquid and to the gravity of the moon which keeps the tides going is technically not the result of stellar creation ;-) )

We are all stardust - but not 100%.

Point being: Power SUPPLY from the sun is fairly integrated over a 24 hour cycle - no matter what the weather conditions on any particular day.
It's just a matter of tapping into the form that it is most readily available in at any particular time.
islatas
5 / 5 (3) May 15, 2012
I've spent a lot of time on and off of the coast of the northeastern US. I've never ever seen it smooth as glass. Mind you I'm not there every day but I've not seen it glassy once in 30 years. Here's a smart move though...if an area has a commonly calm sea don't build wave generators there.

I wonder if people like this were prevalent during the last energy revolution. "Coal will never work. There's no coal in most of the East or West Coast! Timber will never work, there aren't any forests in the plains or the deserts!" Get a grip. Don't be intentionally dim.
NotParker
1.3 / 5 (14) May 15, 2012

I wonder if people like this were prevalent during the last energy revolution. "Coal will never work. There's no coal in most of the East or West Coast! Timber will never work, there aren't any forests in the plains or the deserts!" Get a grip. Don't be intentionally dim.


Coal was revolutionary in a good way because of the density of energy. If it had cost 10x or 100x what wood cost to cut and transport and store the coal revolution would only have occurred when we ran out of trees.

There are hundreds of years of cheap natural gas. Only idiots (or conmen) voluntarily spend 10x or 100x the going rate for energy.

Germany (and other stupid countries) is finding that out. And the poor and middle class are getting screwed.
islatas
3.9 / 5 (7) May 15, 2012
There are hundreds of years of cheap natural gas. Only idiots (or conmen) voluntarily spend 10x or 100x the going rate for energy.


Since this is in response to my comment about people opposing research into alternative energy, are you in the group who believes we should just ride out what we have until it's gone? Not one bit of effort should be spent researching the next group of energy solutions? If so I struggle to see how the researchers and those who fund and support it are the idiots. Please remember to unplug everything when the time comes for you to put your foot in your mouth.
Vendicar_Decarian
3.5 / 5 (8) May 15, 2012
Poor ParkerTard. He has never purchased a battery in his entire life.

"Only idiots (or conmen) voluntarily spend 10x or 100x the going rate for energy." - ParkerTard

Idiot.
Vendicar_Decarian
3.5 / 5 (8) May 15, 2012
Poor ParkerTard. He thinks that a bouy and a small 500 watt generator are going to cost 5 million dollars.

"And cost 15x more than your home." - ParkerTard

But then the mentally diseased like ParkerTard often live in a land of self delusion and fantasy.
NotParker
1.3 / 5 (13) May 16, 2012
Verbal Diarrhea spews: He thinks that a bouy and a small 500 watt generator are going to cost 5 million dollars.


And the battery. And wiring to the shore.

How much for a 24 hour battery capable of 500 watts and hundreds of charges/discharges per year plus the wiring to the shore?
NotParker
1.3 / 5 (13) May 16, 2012
There are hundreds of years of cheap natural gas. Only idiots (or conmen) voluntarily spend 10x or 100x the going rate for energy.


Since this is in response to my comment about people opposing research into alternative energy


I have no objection to research. But building the stupid expensive things in large numbers is for idiots who want to squander trillions for no return.

As of when I write this, the 120 billion pound wind turbines (and that is probably 10% of the real cost) is putting out .397GW for the UK and the current demand is 41.18GW.

.96%

Assuming the lowball estimate of 120 billion pounds, they would need another 11 trillion pounds of wind to get 100% of their needs.

And sometimes wind goes to zero.

http://www.gridwa...r.co.uk/
NotParker
1.3 / 5 (13) May 16, 2012

Assuming the lowball estimate of 120 billion pounds, they would need another 11 trillion pounds of wind to get 100% of their needs.

And sometimes wind goes to zero.

http://www.gridwa...r.co.uk/


To put 11 trillion pounds in perspective. The UK budget for 2013 plans to spend 125 billion pounds on healthcare.

If the UK totally stopped healthcare spending for 88 years, they could get to 100% wind power.

Of course the turbines built in the first 60 years would have worn out by then ...
NotParker
1.3 / 5 (14) May 16, 2012

As of when I write this, the 120 billion pound wind turbines (and that is probably 10% of the real cost) is putting out .397GW for the UK and the current demand is 41.18GW.

.96%

Assuming the lowball estimate of 120 billion pounds, they would need another 11 trillion pounds of wind to get 100% of their needs.

And sometimes wind goes to zero.

http://www.gridwa...r.co.uk/


Update: 0.178GW out of 38.47GW = 0.46%

26 Trillion
LaserLips
not rated yet May 17, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


Awesome! Nice to put it in perspective like that. I originally thought "that doesn't sound like much."
NotParker
1.3 / 5 (13) May 17, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


Awesome! Nice to put it in perspective like that. I originally thought "that doesn't sound like much."


One electric space heater uses 1440 watts.

One normal size A/C unit uses 900 watts.

One clothes dryer uses 4400 watts.

One electric oven at 350 uses 2000 watts.

etc

http://michaelblu...uch.html

Perspective ... to dry your clothes you need 9 of of those buoys ... as long you don't want to cook anything or turn on the lights or turn on anything else.
NotParker
1.4 / 5 (13) May 17, 2012
500 watts of continuous power generation would produce more than 1.5 times as much energy as my home uses currently.


Awesome! Nice to put it in perspective like that. I originally thought "that doesn't sound like much."


One electric space heater uses 1440 watts.

One normal size A/C unit uses 900 watts.

One clothes dryer uses 4400 watts.

One electric oven at 350 uses 2000 watts.

etc

http://michaelblu...uch.html

Perspective ... to dry your clothes you need 9 of of those buoys ... as long you don't want to cook anything or turn on the lights or turn on anything else.


Oh, and if you live in a cold climate, you need 53 buoys if you have an electric furnace - 26,500 watts.
Feldagast
2.2 / 5 (5) May 20, 2012
Wonder if VD is using watts or kilowatt hours.
Urgelt
5 / 5 (1) May 21, 2012
Power generation efficiency can't be very good with such a small prototype. From the sound of it, they aren't looking to scale it up, either, just refine it.

Well, it's good basic research. Much of the challenge coming from ocean kinetic is a materials challenge: finding the right combination of materials that can stand up to the ocean environment and produce power reliably with little maintenance.

I'm not convinced that a small bouy deserves a place in our energy big picture, but I am convinced that we must learn to tap ocean kinetic energy. The energy density and ubiquity of ocean kinetic are very large advantages.
antialias_physorg
1 / 5 (1) May 21, 2012
From the sound of it, they aren't looking to scale it up

not by size, but I'm fairly certain this would scale up by numbers. Oceans are big. Making lines a few hundred kilometers long comprised of these things would not impact anyone.