Renewables let you have a more diverse set of energy inputs so you aren’t putting all your generation eggs in one basket. One type of renewable that doesn’t see a lot of love, despite 80% of the world’s population living within 100 km (~60 mi) of a coastline, is harnessing the energy of the tides. [via Electrek]
“The U.S. Department of Energy’s National Renewable Energy Laboratory estimates that wave energy has the potential to generate over 1,400 terawatt-hours per year,” so while this initial project won’t be huge, the overall possible power generation from tidal power is nothing to sneeze at. Known more for its role in shipping fossil fuels, the Port of Los Angeles will host the new wave power pilot being built by Eco Wave Power and Shell. Eco Wave’s system uses floaters to drive pistons that compress hydraulic fluid and turn a generator before the decompressed fluid is returned to the pistons in a nice, tidy loop.
Eco Wave plans to finish construction by early 2025 and already has the power conversion unit onsite at the Port of Los Angeles. While the press release is mum on the planned install capacity, Eco Wave claims they will soon have 404.7 MW of installed capacity through several different pilot projects around the world.
We covered another Swedish company trying to harness tidal power with underwater kites, and if wave power isn’t your thing but you still like mixing water and electricity, why not try offshore wind or a floating solar farm? Just make sure to keep the noise down!
California should make a goal to scale a decentralized network of these across the state along side desalinization plants to become water independent.
I know the Eco Wave website talks about “compressing hydraulic fluid” but isn’t that stuff usually considered incompressible? That’s why it works to transmit force in a hydraulic system, I thought. Anyone with more knowledge about this kind of thing able to weigh in? Or are the forces involved big enough that it’s actually compressing the fluid?
You are technically correct (no meaningful volume change is occurring), but you forgot that languages are made up as people go along.
“Pressurized” would be a more accurate word choice, but “compressed” is often used informally/colloquially.
It’s a free hill for you to die on, if you like! My hill to die on is the correct usage of ‘jealous’ and ‘envious’.
Just wanna say I’m with you on jealous vs envious there. ✊🏻
“My hill to die on is the correct usage of ‘jealous’ and ‘envious’.”
I’m jealously envious of your statement!
“Compressing” isn’t the correct verb. “Pressurizing” is more accurate. The pistons are merely pumping hydraulic fluid from a low pressure reservoir to a high pressure reservoir.
compressing hydraulic fluid likely refers to one of two things,
1, the forced movement of hydraulic fluid by applying compressive force to a hydraulic cylinder
or
2. the storing of hydraulic fluid under pressure by driving it into an accumulator, a vessel designed with either mechanical or pneumatic compression elements.
Hydraulic fluid is compressible, just like concrete and blocks of tungsten. Somewhat less than air however
Try 1000x less
I work as a hydraulic technician: “pumping” is probably a better word. But their system also has a hydraulic accumulator, which has oil on one side and compressible gas (nitrogen) on the other side. This does indeed store energy as pressure, and functions as a direct analog of a capacitor. A large bank of accumulators can be used as a sort of super capacitor or battery, but an elevated reservoir of the pumped fluid (oil) would be a better analog of a battery.
I believe the description of the system was incomplete. True, hydraulic fluid is non compressible. The pistons likely build pressure, possibly air, against the hydraulic fluid which then drives turbines. A control valve, much like a thermal expansion valve used in refridgeration would be necessary.
The port of Los Angeles is behind a breakwater. Not much wave action. Maybe they don’t need much.
They are likely installing ALONG the breakwater AT the port of Los Angeles.
Decades ago people thought dams were a great idea. They produced power and prevented flooding. Some provided recreation in the constrained waters. Then people worried about fish migration. No problem, alternate paths were added. Then people said the natural process of flooding, being interrupted, was bad for the ecology. But by bit some dams were damned.
Now we want power from waves. The immediate result is that power comes from reduced wave heights. What, in the fullness of time, will “people” say about that effect ?
People can’t accept tradeoffs. They all want something for nothing. TANSTAAFL.
“They produced power and prevented flooding. Some provided recreation in the constrained waters. ”
They also supply water for agriculture and communities.
You know I’ve always wondered about some of the future global ramifications of widespread renewable energy sources.
Things like hanging weather patterns from ultra high scale wind farms slowing winds and solar panels utilizing too much of the energy that makes it into our atmosphere.
Say goodbye to birds for one thing
The total energy reaching the earth from the sun remains the same, and in the cases of solar and wind it mostly gets converted to heat. Some solar (radiation) is converted to carbon & oxygen by plants, and the rest just goes to heat up the surface. Wind only heats up the surface (by friction)… I don’t know any natural process that uses wind to grow!
Siphon off a little to convert to electricity, move it somewhere, and within hours (if not immediately) it gets turned back into heat.
Unless you start beaming terawatts of power off into space, the planet still ends up with the same amount of energy that it always has.
Amen, agree 100% with that statement.
Since the tides are powered by the Moon’s gravity, I wonder how many thousands of years before harvesting energy from the tides until we see a noticeable impact on it.
It’d be interesting if the eco concern of the far future was the moon hitting the Rorshe limit.
The moon is 384,400 km from the earth. It is estimated that its rorshe limit is 19,900km. The moon is slowly moving further away from Earth at a rate of about 3.8cm per year, so there really isnt a risk of it hitting the rorshe limit.
Harvesting the existing energy of the tides would have no effect whatsoever. There is no up regulation if tidal energy if some is consumed instead of being wasted. Unless you MASSIVELY increase the amount of water in the ocean, the moon wont be affected.
The moon is not the problem, tidal energy to harvest is from earths rotational energy. So when all tidal energy has been harvested (or naturally used up by the tides), the earth rotation will be locked to the moon as the moon rotation is already locked to the earth.
The earths rotation would not LOCK to the moon, The moons rotation would lock to the EARTH and it would take billions if not trillions of years for the Moon to reach a point where it is so significantly further away for its orbit to stop.
Whether we harvest wave energy or not, the rate the earths rotation slows remains the same. The day has been getting longer and longer by about 0.0016 seconds each century. Barring some unforeseen force dramatically increasing the rate of deceleration that event is 3,509,807,687 years away, So the likelihood of humanity existing when the earth becomes rotationally locked to THE SUN is insignificant.
thanks for calculating :)
Btw, moons rotation is already locked to earth, that’s why we always see the same side from here, they probably had too many tidal power plants for powering the electric car they used on the moon missions :-D
@matthias Yeah Im aware the moons already locked, I was just trying to point out that if the earths rotation stopped the moon would not hang in a stable sky point. For that to happen the moons orbit, not the earths rotation is what would have to stop….well unless we hit that bizzaro theoretical sweet spot where the moons orbit and the earths rate of rotation synchronized.
Well, earths rotation would not fully stop, it would only slow down to the point of 1 day = 1 month. At this point “earth rotation is locked to the moon” and “moon orbit is locked to earth” are the same thing, and the eath/moon tides no longer extract rotational energy.
The tidal forces of the sun on the moon/earth system are somewhat smaller, but it is probably interesting to investigate, if they are strong enough to mitigate or disable the moon/earth locking, or if they just cause a swing around the lock point.
It’s “Roche limit”, guys.
And have no fear that our moon will encounter it. As mentioned, the Moon is moving away: The action of tides is extracting energy from the rotation of the Earth and imparting it to the moon, increasing its orbital radius.
My mistake. Then how long until the Earth becomes tidally locked to the Moon?
Depends on tidal energy losses (deforming masses – water, stone – and other mechanisms as tidal power plants); the energy available is in the rotational speed (calculate with earth mass and rotational inertia of a sphere minus the energy in the tidally locked system with the same rotational impulse), and the decay is asymptotical until the rotational energy is lower than the energy needed to move earths center of gravity full circle around the common gravity center of the earth-moon-system (then the rotation becomes a rotational pendulum).
I’m sure someone has already calculated that with reasonable assumptions about the losses, and without all the mistakes I made when thinking about it :)
Isaac Asimov once wrote a science essay about this very thing. I forget the exact figure he came up with, but it was comfortably longer than it will take for the Sun to become a red giant and swallow both the Earth and the Moon up.
Ok, meanwhile I did some math, too. Let’s compare numbers.
radius of earth r_e=6,37e6 m
distance moon to earth r_me=384e6 m
masses of moon and earth: m_m=7,35e22 kg, m_e=5,974e24 kg
rotational speed: w_e=2pi/86400 s = 23,148e-6/s w_m=w_e/27,3=0,848e-6/s
moment of inertia J_me=mr^2 (assuming all of it being on the moon side and the moon being a point of mass, r is r_me)
J_e=2/5 mr^2 (assuming earth is an isotropic sphere, r is r_e)
energy W=0,5Jw^2
angular momentum L=Jw
J_e=2/5 x 5,794e24 kg x (6,37e6 m)^2 = 97e36 kg m^2
J_me=7,35e22 kg x (384e6 m)^2 = 10,84e39 kg m^2
L_e=J_e x w_e = 2,2454e33 kg m^2/s
L_me=J_me x w_m = 9,19e33 kg m^2/s
L_tot=11,4354e33 kg m^2/s total momentum of moon-earth system must remain constant.
Energy in system now:
E_e=L_e x 0,5w_e = 26e27 Joule
E_m=L_me x 0,5w_m = 3,9e27 Joule
Energy after tidal lock (assuming the moment of inertia of the rotating moon stays approximately constant and the remaining momentum of earth is neglible)
E_L=0,5 x J_me x (L_tot/J_me)^2 = 6e27 Joule
So there are 23,9e27 Joule available for use on tidal purposes. Divided by the remaining time until lock from [makes you go hmmmm….] makes per annum E=6,81e18 Joule, or 216 GW to power the tides. Sounds reasonable, and as long as we don’t exceed this power too much the effects shouldn’t matter. On the other hand the rotational energy does not recover, so I’d count tidal power plants as fossil energy source.
… any corrections? I can’t believe I didn’t mess up somewhere.
@matthias
What you continue to seem to misunderstand is that whether we harvest the energy or not is inconsequential. Using wave power will not stimulate greater wave production. Its like solar. No matter how many panels are connected the sun doesnt care and will continue to do its fusion thing at the same rate regardless.
Fossil fuels exist in a set quantity. The more we use them the faster they are depleted. The same is not true for solar, wind, nor wave power. Sure if you play with the maths long enough everything has an eventual expiry, but in the human scale of things the end date of solar, wind, and wave energy are inconsequential. These forces will continue to exist longer than humanity.
@matthias
What you continue to seem to misunderstand is that whether we harvest the energy or not is inconsequential. Using wave power will not stimulate greater wave production. Its like solar. No matter how many panels are connected the sun doesnt care and will continue to do its fusion thing at the same rate regardless.
Fossil fuels exist in a set quantity. The more we use them the faster they are depleted. The same is not true for solar, wind, nor wave power. Sure if you play with the maths long enough everything has an eventual expiry, but in the human scale of things the end date of solar, wind, and wave energy are inconsequential. These forces will continue to exist longer than humanity.
Correct. My calculations are about tidal energy, so it is pretty off-topic here, sorry about that. Wave energy doesn’t deplete, since it originates mainly from wind blowing across the surface.
One benefit of harvesting wave energy may be that it keeps said energy from biting into the harbor walls, but for this to take effect the harvester needs to collect (the waves) peak power during storms, which seems difficult to me.
All the rusty metal and cracked concrete in that picture tells you why we don’t have more wave power – the sea will f*** everything you put in or near it. Boat owners know this.
That is why we hardly see any boats – they are totally impractical.
Now I am wondering about the drag – coefficient effect on the earth’s rotational speed as well as its axis shift due to all those boats sticking out above the earth’s waters surfaces over millenia.
Correct. I’ve seen 316 rust through. It’s a running joke here that the official company color is rust-brown, because everything ends up becoming rust color. If it can rust, it will rust. It’s called stains less, it’s not called never stains.
“We covered another Swiss company trying … ” Swiss company? Swedish company!
An old joke is as follows: A non-european tourist makes the statement “Stockholm is a nice town, and Switzerland is a nice country”.
What is often overlooked: Switzerland has no sea access. There is a kind of tidal movement (‘seiches’) in Lake Geneva, but it is too weak to be used economically
“Smoke on the water,
Fire in the sky!”
Gah, I even checked to make sure they were actually both the same, but somehow garbled it in my feeble American brain! Should be corrected now, thanks!
But what about the moving parts? What’s the life time of metal in sea? See weed/algae growin?
How much human labour will it be to clean it, meanwhile waves not crashing you.
Even wind power seems longer lasting/sane than this.
Doesn’t matter, got grant money and green PR
The main problem is that everything is mechanical, made of steel, and needs bearings. And then it’s all brought into more or less permanent contact with very salt water…
You’re conflating “wave power” with “tidal power” here. Different things. You can have waves without tides, and tides without waves.
Exactly what I was going to say. This article describes a project to get power from ocean waves. There have also been projects to draw power from tidal flows, like the “underwater kites” mentioned.
Surfs up ! Ummm, wait, what, there’s no waves to surf anymore ?!?
IIRC there was a pilot project to harness wave energy in Hawaii (?) It used buoys with linear generators anchored offshore. I wonder about it’s efficiency and practicality compared to this approach.
I saw at least ten different kind of projects in the last 30 years that tried to harness energy from ocean waves. Even in this article I couldn’t find anything about projected project cost and expected power.
I suspect this will also not really economically feasible. Maybe they figured out something that the others did not, but I would not expect too much from this project without some concrete results first.
Wave Energy is present 24/7/365
“24/7/365”
I’ve never liked this notation. If it’s 24 hours a day/7 days a week/365 days a year, isn’t the 7 and 365 redundant? Shouldn’t it be 24/7/52? or just 24/365? Off topic I know, but there’s my $.02
24/7/52 I had never thought of it that way.
But now I might start using it to mess with people’s minds!
B^)
And you get one day off per year. Two days on leap years!
I’ll need those days off!
B^)
I think the biggest problem with this in California is that coastal property is some of the highest priced land available. I’m sure California beachfront land owners will prevent this from happening near their ritzy homes. NIMBY is a huge problem.
If I were a cliff dweller in California I would wholeheartedly embrace a device to extract energy from the waves before they hit my piece of coast. Energetic waves erode cliffs.
As for the “Tidal Power”: The French have been doing it since 1965.
https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station
.