Japan tested a giant turbine that generates electricity using deep ocean current | Hacker News Reader

Japan tested a giant turbine that generates electricity using deep ocean current

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222 pointsjdmark204 comments

The turbines are very interesting, these demonstrator projects seek to answer questions like how do you even make one, how do you install it and how do you maintain it… a very interesting piece of hardware required to scale this up (in deep water anyway!) is a subsea substation to up the voltage from the array to export voltages…

The article mentioned 100-160ft from the surface, so i'm not sure where the "deep" part mentioned in the headlines comes in. Perhaps their ultimate plan is for deep & this demo didn't try to address the deep part? That said, if 100ft below had enough forces to produce 100kw (ecological issues aside) that sounds pretty fantastic, even if just a demo.

I imagine the "deep" aspect is that it seems to be well below surface waves that seem to reek havoc on other projects. That depth is still pretty difficult to service as install without pretty sophisticated planning I would think.

They would be easier to service than off-shore wind turbines. You just need a light cable attached to a buoy, the service ship goes to the boy, pulls up a heavier cable with the light cable, then pull up the whole structure.

Come to think of it, the turbine pods may include a ballast tank that can be evacuated, to adjust the height in normal operation or to pull itself up to the surface for maintenance.

I'm not so sure. For a wind turbine a lot of maintenance can be done without any additional vessel / cranes. If you need to do a major component change you do it with a similar vessel to the ones which installed the turbine. For a subsea tidal turbine you'd need some frame or similar to land the tidal turbine onto, you'd need to clean it before anyone could access it for the maintenance etc. Generally speaking if you have something subsea it should be designed to be maintenance free as recovery costs are so high (like subsea oil and gas production systems).

unless it's a rigid structure mounted to the ocean floor then it will almost definitely have ballasts

The article explicitly states they are free floating tethered to the ocean floor. And this is by far the easier way, I'd think.

I actually thought the 100kw number sounded awfully low. A typical wind turbine generates around 2 or 3 MW of power at capacity.

That’s the rating at capacity though, which barely ever happens. The ocean current will never stop, so over the course of it’s life the ocean turbine might well beat out a wind turbine (ok, I consider that mildly unlikely, but it’s nice to have power generation that’s less susceptible to suddenly not producing anything).

Also note they say it produced 100kw, not what it was rated for.

The turbine capacity is reached quite regularly, particularly during windy days.

UK Crown Estate have a map of current renewable generation (https://www.thecrownestate.co.uk/en-gb/what-we-do/asset-map/) and right now the Hornsea 1 field is generating nearly 900MW (~90% capacity) on not a particularly windy day for the North Sea. The capacity factors you read are averaged over a year.

I'm not good at nautics, but in my understanding currents slowly stop and later turn around. Most tide charts are more or less a sine wave, with different highs and lows.

So it's interesting how this 100kw was produced.

The article only says: "The business was able to generate roughly 100 kilowatts of steady electricity during demonstrations earlier this year."

So is this over a few days or just a few hours while peak flow? While currents change, their change is highly forseeable - unlike wind.

Currents are relatively unrelated to tides, and are fairly consistent over time (with some seasonal variation due to differences in hemispheric temperatures).

From [1], "the large scale prevailing winds drive major persistent ocean currents..." Keyword is persistent.

[1] https://en.m.wikipedia.org/wiki/Ocean_current

Everything is fairly consistent until you monitor it 24/7, and put a bunch of junk in the way to extract meaningful work.

That's when life starts taking on a surprising level of detail that no one ever stared long enough to notice before.

I imagine that's one goal of the project? I can't imagine that there hasn't been a shit ton of experiments with "deep" sea currents before this power experiment. I mean it's dead obvious and they wouldn't have ponied up the cash for this if ocean currents were all over the place.

The pods with the turbines are floating in the water, tethered to the seafloor, so they will turn in any direction the current is going.

Those wind turbines have been refined for decades and are now a lot larger than they have been at the start.

As far as i know these questions were answered more than 20 years ago.

I'd be worried about corrosion over time... especially in deep sea regions how do you go about maintaining them?

I'd imagine if the energy output ends up being worth it they could manufacture the turbines from some sort of plastic or composite that doesn't corrode in sea water.

This is a solved problem, oil rigs, off shore oil platforms, etc.

Maintaining subsea turbines is not a solved problem - they exist but none have been around a long time, and no large utility scale projects use them so no one has experience with a fleet of subsea tidal turbines. Static subsea structures are proven by the industries you state, but not large turbines.

The laws of physics would dictate that this energy would come from somewhere. If enough power is generated, it will significantly alter the ocean flows dynamics. Deep ocean flow currents can very much affect the climate. Did anybody researched that this would be Ok?

The same could be said about wind power.

Ultimately, wind and ocean currents are driven by the 170,000 terawatts of solar irradiance continuously hitting the earth[1]. Human civilization uses about 17 terawatt[2], so we still have a ways to go before we get in the same ballpark.

(On the other hand, give it a few centuries of exponential growth and let's see where we end up.)

[1] https://news.mit.edu/2011/energy-scale-part3-1026 https://www.theworldcounts.com/stories/current_world_energy_...

[2] https://www.theworldcounts.com/stories/current_world_energy_...

And with this one, currents - mainly ebb and flow - are caused by the gravity of the moon pulling on the oceans.

But yeah, it will have an effect; the other question to ask is, how significant is this effect, and how does it compare to other forms of power production, e.g. fossil fuels?

The global warming caused by fossil fuels has a bigger effect on the oceans; with decreasing salinity due to the melting of ice caps / glaciers, the gulf stream is slowing down and will eventually stop, causing distribution of heat across the planet to stop, causing the northern seas to cool down and the southern ones to heat up.

Tidal flows are a pretty massive energy reservoir - basically you’ve got all the potential and kinetic energy of the moon’s orbit to draw from. That’s (according to my crude Wolfram Alpha based research) about 3e28J of kinetic energy plus 7e28J of potential energy, for a total of 10^29 Joules. Technically a non renewable resource, but you would be hard pressed to make a dent in that energy budget with any kind of human scale extraction project.

I think it’s the rotational inertia of the earth, not the kinetic energy of the moon. Since the earth is spinning faster than the moon orbits, the tides actually are pulled ahead of the bulge the moon creates, transferring energy from the earth to the moon.

Eventually the earth will be tidally locked to the moon (just like the moon is to the earth), and the moon will be in a higher orbit.

I guess the turbines will speed this up? As they’ll keep the bulge farther ahead of the moon.

EDIT: Wikipedia link https://en.m.wikipedia.org/wiki/Tidal_acceleration

That's true - for some reason I was thinking of tides as following the moon's orbit, when of course they're caused by the earth spinning underneath the moon (tides occcur daily, not monthly. Always check your working against reality, kids).

Weirdly, the resulting pool of energy is pretty much the same size - wikipedia quotes the rotational kinetic energy of the Earth as being 2.138E29J.

So we're still talking about an insane amount of energy.

If you use 17.7TW as the total power consumption of all of humanity, if we were to somehow derive ALL of our energy needs from tidal generation, it would take 358 million years to deplete the rotational energy of the earth.

Would the turbines make the rotation decay faster, or would they just put some of the energy of rotation decay that happens anyways on a slightly different path towards heat?

Technically a non renewable resource...

How's that? Can we consume it? What would be the reaction? Moon altering its orbit?

Yes this technically degrades the moons orbit. Do it long enough and hard enough and the moon will hit the earth. Shouldn't be of any concern though, because the kinetic energy the moons movement is carrying is insanely high.

This doesn't degrade the moon's orbit lol. The energy is there regardless of whether we are using it or not, it will go somewhere, this is just making "useful" work out of it (if anything humans do to the environment, other than going extinct, is really value added for the environment)

Huh. Would Ice 9 also make the moon crash?

I think this is targeting ocean currents, which are solar-powered convection between the tropics and the poles, rather than tidal currents.

Currents, on the large scale, are not caused by tides. Surface currents (down to 300m or so) are driven by prevailing winds, and deep currents driven by differences in temperature and salinity (which affect water density), both also affected by Coriolis effect.

That 170,000 terawatts hitting earth is dwarfed by the 400 trillion terawatts output by the sun, so we can always build some fraction of a Dyson sphere if we start to run short with the 170,000

The sooner we stop using these feeble fossil fuels the better

Fantasy solutions don't work for real problems. We have the capability to make real problems via terraforming.

A Dyson sphere is just as much fantasy as physics, true of most of today's technology just 50 years ago.

Solar and wind are needed today, but Starship could bring launch costs down enough that some highly optimized space solar panels with microwave power beaming could be viable within a decade.

I believe the solar panel part, but not on the microwave power beaming; has that been proven to work already? How efficient is it? What is the effect on anything flying through or being near where said microwaves are received?

Solar panels in space is the believable part; rays of concentrated energy being sent back to earth is what I'm skeptical about. Besides, solar panels have a limited lifetime; I don't believe space solar panels are a cost effective solution to solving the energy crisis.

This idea keeps being brought up and people keep reminding everyone that for all intents and purposes this is the closest to a cartoon supervillain death ray that we can create.

I think the important point is that we’re reasonably certain we can create it.

Yes but could we please not? Orbital death rays for power generation seem like a bad idea when we have options like rooftop solar and wind turbines.

Right, but what do we do when we’ve covered every surface of the earth with solar panels and wind turbines?

We’ll need to move into space sooner or later if we want to continue exponential growth.

We'll just have to clear some area, I suggest the quickest way would be with the giant orbital heat beam! :D

(100% agree that getting into space is important, and that if we want to continue exponential growth we'll need more than one planet. In fact, we'll need more than all the planets and we fairly rapidly (in cosmic terms) hit the point where the available volume of our light cone isn't enough. Maybe indefinite exponential growth isn't something we should feel entitled to...)

We're nowhere close to that. Covering all land in solar would be ~100x our current energy needs, and then we still have ocean (most of the surface) available.

Besides, anyone who's played simcity knows the damage that can be done by a wayward microwave power beam.

Why would we build a solar panel that has a microwave emitter instead of just building a mirror?

Is our atmosphere more or less transparent to some parts of the frequency spectrum than others? Is the diffusion different?

> Is our atmosphere more or less transparent to some parts of the frequency spectrum than others?

Yes. The frequencies that are not blocked are called "atmospheric windows". And there is indeed such a window for microwaves. These windows also exist for visible light and a range of IR, but those depend more on weather conditions.

https://glossary.ametsoc.org/wiki/Atmospheric_window

This is the point. High energy needs to be transferred in a narrow beam, and be minimally impacted by all layers of our atmosphere

How would capturing the beamed energy on earth be any easier than capturing sunlight directly?

Maybe illuminate existing solar arrays during nighttime? Any other energy receiver would be so far behind PV on the price / manufacturing learning curve

Main benefit is avoiding transmission losses through our atmosphere. Capturing the signal is easy (we have satellite communication already)

>> Maybe illuminate existing solar arrays during nighttime?

I never thought about this. Is there some orbit where this becomes feasible?

A sun synchronous orbit above the terminator would do it.

Receiving energy that was not supposed for earth will increase planet heat output (because electricity in the end will heat things). Who knows how that would affect the planet.

The only way to preserve the Earth is smart planning, reducing energy usage and moving industry to the space. IMO Earth should be sanctuary for people to enjoy their origins and for some rich people inevitably. Most people should move to other planets or space objects where pollution does not matter.

Terraforming is a fantasy that won't work for real problems

>We have the capability to make real problems via terraforming. [emphasis mine]

Yes, they slightly misread, but it's a fair retort. Terraforming is pretty fantasy, but it happens.

We’re carbon (de-)terraforming the earth everyday on a global scale, haven’t you heard? It’s very real

This with assumption that there is linear relation without butterfly effects, even if there are negative effects, most likely they are negligible when compared to green house effect on the planet, my false intuition tells me that power generation from wind and ocean currents would contribute to planet cooling, no idea if electricity converted to work will radiate heat faster into space then air and oceans passively.

Just to point out, we would be harvesting a lot more than we use because of inefficiencies in capturing, storage, and transmission strategies. Also note that the amount we use is lower than it would otherwise be if we had access to more energy, industry is energy-constrained.

In the case of something like PV, would that matter too much? The inefficiency doesn't mean the rest is lost, just that it stays in the local environment rather than get transmitted away somewhere else on a wire.

Pretty much. As an examples, in deserts, there can be a modest increase in local IR radiation because of the change in albedo from PV panels compared to sand, but the overall decrease in IR from avoiding the CO2/etc emissions of fossil fuel generation is much, much larger than the local increase.

10% reducation in currents and wind surely would have massive impacts on the planet?

Well 1) living has a massive impact on the planet because everything we do leaves a mark and everything we eat redirects energy into our bodies so that ship has sailed and 2) a 10% reduction in currents and wind specifically would have massive impacts on the planet’s currents and wind if we built enough power plants that used those sources of energy specifically to power the entirety of human civilization. We have other options, and the way we source power (as a planet, never mind individual jurisdictions) is basically an “all of the above” energy strategy in practice. However we can source energy, we do it.

Flowing water has insane amounts of energy even in tiny amounts. I would imagine that this affects ocean currents as little or less than wind turbines affect weather patterns.

"It's so vast that small human actions couldn't possibly have an impact" is literally the same wrong-headed reasoning that leads people to believe that human CO₂ emissions don't matter.

There seems to have been a lot of extreme weather in recent years. Could it be because harvesting energy from the wind alters weather patterns? A lot of people would rather just blame it on global warming than ask a question that might expose a flaw in our plans to wean ourselves off of fossil fuels.

We need to have bit more humility and a bit less dogma about what we "know".

The mechanism by which CO2 raises the steady-state temperature of the atmosphere is well understood, and it is not because of the awesome power of CO2, it is because the Sun is incredibly energetic.

By contrast, there is no known way that wind power extraction, which is currently < 1TW globally, could possibly be destabilizing the energy system of the rotation of the Earth (which is what causes wind). That system contains ten billion times more kinetic energy than we remove from it annually.

The amount of kinetic energy the moon removes from the Earth's rotational kinetic energy every year is larger, and has been going on for a long, long time, so if it was going to cause fire weather that would already have been a long-standing problem.

In short, the amount of CO2 that humans have dumped into the atmosphere in the last 200 years is comparable to the amount that was in there to begin with. It can't be ignored. But the amount of energy we remove from the wind is nine or ten orders of magnitude smaller than the total amount that exists, and therefore it can be ignored.

The reason CO₂ emissions matter so much is that they accumulate over time.

> There seems to have been a lot of extreme weather in recent years. Could it be because harvesting energy from the wind alters weather patterns? A lot of people would rather just blame it on global warming than ask a question that might expose a flaw in our plans to wean ourselves off of fossil fuels.

Do you have anything other than wild speculation? Because in most cases slowing down air currents should calm the weather.

And of course this has been asked!

Slowing down air currents doesn't necessarily decrease extreme weather. Air currents are a means of energy diffusion. Stopping up that process is more likely to just exacerbate local maxima. Stabilized local maxima can be useful for energy extraction while being quite inconvenient for just about everything else.

Energy races to heat. Heat tries to diffuse. If it can't, it's still there. Moving it still costs more energy.

Entropy always wins.

I don't think we will ever see power generation via renewables (one industry) approach the scale of anything near carbon emissions (all industry)

You could do some very basic napkin math multiplying the air displacement per turbine (or whatever metric you choose) and multiplying by every turbine that exists, and I'd bet that number would be nowhere near total air displacement from natural causes.

Human CO2 emissions matter precisely because the math has exceeded change from natural causes. And this happens because literally everyone is doing it. IF we cover the planet in wind turbines the same way we cover it with waste C02 then maybe you might have a case.

Not to say renewables aren't without their issues. There are likely a whole host of second- and third-order issues there that have yet to be discovered, let alone resolved. But we would need adoption on a scale far beyond what has been proposed to combat global warming to approach that.

I'm not saying that CO₂ and wind turbines have a comparable effect on the climate. I'm saying that "it's small so it couldn't matter" is the same flawed thinking.

> Human CO2 emissions matter precisely because the math has exceeded change from natural causes.

Why? It's the significant detrimental impact of the human activity that's important, not how it compares to the amount or change from natural causes. (It doesn't even matter that it's human activity. If Earth were going to become inhospitable by entirely natural causes, that would still matter.)

> then maybe you might have a case.

I'm not making the case that wind turbines are harming the environment; that's just the example at hand. I'm making the case that casually dismissing (questions about) the potential impact of human activities is wrong.

My point is that the scale of pretty much everything we do is minuscule compared to carbon emissions. And, short of being more specific on what 'human activities' are in question, the negative tradeoffs are going to have to be far worse, in order to be a worse alternative than our current course of spewing CO2.

I don't think there's really much energy in ocean currents. Based on the numbers from here [0], it seems you can get no more than 20 GW from the entirety of the Kuroshio current (the big one near Japan that they're targeting). That's not really a lot, and presumably the environmentally safe level is a fraction of that, after which you're fucking up heat transport on a planetary scale*.

(Maximum flow of 65 sverdrups = 6.5e7 m³/s, and a top current speed under 1 m/s. Density of water is 1e3 kg/m³, and there's also a subtle multiplicative factor of 0.6, from Betz's law).

[0] https://tos.org/oceanography/assets/docs/28-4_andres.pdf ("Mean Structure and Variability of the Kuroshio")

https://en.wikipedia.org/wiki/Sverdrup

https://en.wikipedia.org/wiki/Betz%27s_law

*(Footnote because this stood out to me as weird, but the math holds up: the amount of heat energy transported in ocean currents is >10⁴ times greater than their kinetic energy (what ocean turbines can extract). 1 kg of water stores 4,200 J per 1 °C temperature increase, but only 0.5 J of kinetic energy at 1 m/s. So I think that blocking an ocean current would have a disproportionate amplifying effect on the climate. IANAO).

Appending to my comment: actual experts say the potential isn't 20 GW but 200 GW. I don't know where I made my error.

https://www.bloomberg.com/news/features/2022-05-30/japan-s-d...

- "Japan’s New Energy and Industrial Technology Development Organization (NEDO) estimates the Kuroshio Current could potentially generate as much as 200 gigawatts"

This is like worrying that wind turbines will stop the wind.

They won't.

No, it’s asking a question about our knowledge of the scale and power of the devices and forces involved.

If it is a analog to wind turbines, the math will bear it out, but it’s a perfectly valid question to ask.

Exactly just a few decades ago CFC was a non issue, Lead caused no harm, smoking was good for health, and cocaine was a refreshing drink. Yet here we are again so full of ourselves that asking the question is unsettling.

So we should keep doing the known harmful power generation methods (coal) instead of experimenting with new methods (deep sea turbines) out of a diffuse fear of the unknown consequences?

It’s sad that this is such a common argument against progress. Where do people learn to think this way? Does it come from education? Failures in life?

Nobody said that.

The concern is that more information should be discovered about the effects, and that is usually done through experimentation.

> ”Where do people learn to think this way? ”

Where do people learn to create straw man arguments instead of actually replying to what was said?

Have you ever heard the saying:

"The grass is always greener on the otherside."

I believe that's where this line of thinking comes from.

Have you ever tried to change lanes because yours isn't moving, just to find that right after you change to your new lane it stops and your old lane picks up again? Man that sucks

Nopes move fast and break things. Only issue is that Earth is not a software system which can be fixed with upgrades.

There is a scale that they would. We are orders of magnitude away from that scale. It's an interesting line of thinking to imagine the scale required to significantly change the winds.

We’re arguing semantics but on a big enough scale they would eventually. That’s why you don’t just line up 100 of them directly next to eachother.

Agree that this is effectively arguing semantics, and it is taking energy from the wind. But the effect of each _is_ very small. There are definitely farms with >100 turbines close together. This one has >600 and has long runs of them close together. https://en.m.wikipedia.org/wiki/Alta_Wind_Energy_Center

while that one produces more electricity, this one has about twice as many turbines in close proximity: https://en.m.wikipedia.org/wiki/San_Gorgonio_Pass_wind_farm

Other people will explain why you are wrong to be concerned. However your concern is indicative of the concerns of a significant, potentially majority, of people. It shows how as a society we don't do messaging about this sort of thing well enough. I think thats an important take away.

To oversimplify, I think the default posture in western society has become "let's not do anything, in case it goes wrong".

People who think like that are seen as serious people who don't foolishly ignore all possible negative consequences.

I, as the reader might guess by now, don't have high hopes for societies that function this way.

Nooo... The default is "do your due diligence".

As it turns out, there's a LOT more we can do now (that is actually hard work to boot) than we've necessarily been able to do before.

If you actually take the phrase "reasonably forseeable" seriously, I assure you, chasing down those nasty little details and feeding them through the math takes a hot minute.

We do a bad job of explaining to residents of our dense population centers how much energy is required to run their city for a single day, where it comes from, and how much it costs to produce.

Don't rural dwellers use more energy, per capita?

Per capita is a poor way of looking at the scope of this particular problem. We can service that one farm with several thousand gallons of diesel. It’s an understandable power generation problem with units normal people understand.

Powering a city is at another entirely different scale, and “diesel” doesn’t come close to addressing the magnitude of that problem.

Persistent deep ocean currents exist in large part thanks to temperature gradients (cf. AMOC and thermohaline circulation). Climate warming, melting ice and reducing these gradients, has much more drastic effects on ocean currents (cf. Gulf Stream weakening) than a turbine could ever have.

Paradoxically, we would effectively be saving those currents using a fraction of the energy in those currents themselves.

Using these turbines would be a drop in the ocean and a smart move if it helps us tackle the big offender. We should get on it soon though, if we let it get to a point where thermohaline circulation falls apart using currents this way may no longer be an option.

I aggree with the necessity of haste, but I hope these turbines can be developed in a way to have minimal impact on all the ocean life that uses these currents aswell, there's already so much damage thats been done to the ocean ecosystems already.

The energy comes from the moon orbiting the earth. Theoretically speaking, taking too much energy would cause the moon to come crashing down to Earth.

The tides are already transferring energy from the Earth to the Moon, making it go higher over time.

I suspect that adding more drag to the tides could either boost this process or reduce it, depending on the timing of the energy harvesting.

What about the compromise, the Moon in geostationary orbit: would be great for broadcasters (no more broadcast satellites, just plant antennas on the moon).

The energy in tidal currents comes both from the moon orbiting the Earth, and from the Earth orbiting the sun. (Technically other heavenly bodies also have some effect, but it's negligible.)

I've always wanted to have a bigger Moon, this might be a way to achieve that.

The energy harvested is only... a drop in the ocean :)

It mostly comes from the Sun. It spews so much energy at Earth that all humanity consumption doesn't make a dent in it.

I would hazard a guess that the energy is ultimately from the moon circling the earth. Not sure how much physics has to scale to put that off balance, but other than damming up an ocean current, I can’t imagine we’d mess it up in the way you mention.

Research how? It's not like they can go from 0% to exhausting wave energy immediately. You'd think people will look into this as the technology grows, but you need the tech to actually be there to research it.

I would also say I'm not a big fan of the activists' line of thinking that artificial changes in the ecosystem being bad (but man-made "conservative" actions are good). I mean you can't possibly prove that and we're way pass "should we alter our environment?"

Maybe that would be good! If hurricanes are powered by hot seas, then removing energy from the seas has got to remove energy from hurrcianes?

True to a certain extent. People forget that Earth is not a zero sum control volume. We get a crap ton of energy from the Sun and the sun power most things on Earth in some shape or form (minus matter formation or radioactive material). The Earth uses around 23,900 terawatt-hours a year. The sun generates about 430 quintillion kWh every hour.

The same can be said about solar panels. An enormous amount of heat is no longer hitting the ground.

The same can be said about humans. An enormous amount of heat is no longer hitting the ground due to man-made structures in general, way more than dedicated solar farms. Very likely putting solar on roofs is more beneficial than letting it just heat up tiles/shingles, while the building shades the ground. You're basically arguing against building civilization. However, I think human's effects on ecosystems is worthy of investigating, but the "solar panels blocking ground heat" concern seems very tangential and likely insignificant compared to the concerns of human's overall impacts on micro/macro environments.

How significant a difference is it that previously it was hitting my roof?

I like the answers to your questions here. I wonder if in 100 years or so, our energy consumption won't be what 640K of memory (enough for anybody?) was around 1980. Time will tell if it will be a drop in the ocean then.

the other way around is also true, the climate affects the flows

seems like an interesting possibility to recapture some of the loose climate energy that we want to pare down

Is this out of the same ballpark as "thermal powerplants will boil the atmosphere."

The entire humankind's power consumption is completely microscopic in comparison to any natural weather phenomena.

We are 0.0000000000001% of energy the Earth dissipates.

It is on the same ballpark, and that's exactly why it's worth discussing. Runaway effects in the same ballpark can easily become issues with a feedback loop mechanism.

Interestingly this was a real concern before testing the first nuclear weapons.

Some scientists were convinced that the chain reaction would ignite enough of a fraction of the atmosphere causing irreparable damage. That concern was ignored because these weapons were critical for the war, and luckily nothing like that ended up happening.

Related, underwater tidal turbines in the Cook Straight, NZ https://www.sustainableseaschallenge.co.nz/our-research/ener...

Duration : November 2017 – June 2019

Anyone know of an update on this?

Did you follow the links to sumaaries of findings? Not sure if that has what you want

https://www.sustainableseaschallenge.co.nz/tools-and-resourc...

Yes but then nothing? Maybe I am too impatient, but the (pretty overwhelmingly positive) summary of the findings in the webinar was published to YouTube Feb 2, 2021. Are they looking for funding for "95 turbines spaced 100m apart in two rows ... producing 90 megawatts"? This is extremely exciting and personal to me. I was born in Wellington (on Cook Strait). New Zealand is a country known for self-reliance, blessed by sustainable energy options (especially hydroelectric and geothermal) and with limited indigenous oil and gas (Maui gas field notwithstanding). This could be a moonshot for Aotearoa.

Don't know much about this topic but salt water is corrosive and underwater repair is incredibly expensive. 100 kW is about 0.01% of the output of a modern nuclear reactor so the installation probably has to be a few orders of magnitudes larger for the project to be economically feasible.

Verdant Energy has been using the New York’s East river to test their design since 2012 with multiple iterations. They’ve demonstrated a triangular configuration with 100kwh production tested. They predict the configuration can do 1,050kwh. Not sure how many they would install, but the East river has a very strong tidal current. The original test turbines were damaged by the current. The gen5 were undamaged. https://www.verdantpower.com/projects

NREL makes the blades https://www.energy.gov/eere/water/articles/milestone-tidal-e...

kWh is a measure of energy; kW is a measure of power. (Power is a more relevant sizing measure for a generator.)

Fair, I know better, one of these days I’ll remember ;) Those are both the power numbers, not the generated numbers.

Hmm, a few years late per SeaQuest’s timeline… I just hope we have a SeaQuest 4600 class sub handy to sacrifice in order to plug the lava flow when the turbines cause the ocean floor to break apart!

Ironically, in the SeaQuest timeline, SeaQuest DSV itself would have been abducted by an alien ship just a few weeks ago. Maybe there’s still hope that Mark Hamill is actually our first contact with an alien species?

Makes me want to go rewatch 90’s sci-fi: Babylon 5, Space Above & Beyond, SeaQuest (season 1 at least), TekWar, TimeTrax, etc.

Space Above and Beyond is very underrated. Still sad it only got one season. If they wanted to redo something they could chose something much worse. It might be a little too pro-American and pro-military for 2022?

The ending of the pancakes episode is still one of my favorite moments of 90s TV ever

Col. Ray Butts.

Guess they couldn't make it to Deepwater Horizon oil spill either.

Seawater contains about 3 ppb uranium. Fully fissioned w. breeder reactors, the U in a current going at 1 m/s would yield about 400x the kinetic energy of that water.

This assumes a perfect and energy free mechanism to collect the uranium.

Sounds like a good job for Maxwells Daemon.

Since it wasn't talking about cost, it makes no assumption that anything is "free". As for perfection, I was assuming the reader could multiply 400 by whatever number < 1 was the actual efficiency.

Unstated was whether the difficulty of running breeder reactors makes this unworkable. It very well might, in practice.

I will note that the demonstrated U collection techniques (like polyamidoxime adsorbers) seem quite cheap enough for fueling breeder reactors.

Luckily we're on it. [1]

[1] https://spectrum.ieee.org/uranium-from-seawater

Only 400x, that’s not bad.

330 tons for 100 kW. Assuming it lasts 20 years (and assuming that's short tons), it's about 17 metric tonnes per GWh. Comparisons: http://lumma.org/energy/lca/

So, slightly better than offshore wind. No bad imo.

Could this disrupt the migrations of species like clown fish and sea turtles?

even if it does, all they have to do is just keep swimming

> Could this disrupt the migrations of species like clown fish and sea turtles?

Not, cute cartoons are safe and will live to suffer a sequel. Nemo is now a girl.

But will disrupt the migrations of real animals that are endangered, like sharks, eels (most vanished in the last 60 years) and mesopelagic squids and fishes that play main roles in fighting human famine.

And the technology will need to find a way avoid getting cluttered by marine snow and filterers settling on it, most probably.

I was also wondering about this and it got me thinking - I'd the turbines would be spinning fairly slowly, and I'm picturing some sort of filtering device behind them that could filter plastics or other pollutants to the ocean. In an ideal setup maybe it can filter stuff out and use that to create more energy

Maybe also not what we want, but it could be cool to see if some new ecosystems set up around these structures

Filtering, eh?

You volunteering to change the filters? By definition, that's a maintenance task.

I wanted to say clown fish don't migrate, but apparently they do..

Those turbines probably move very slowly. Hard to hit or hurt anything at those speeds in the water. Sea life will be more trouble for the turbines than the turbines will be for the Sea life. Noise pollution may be an issue.

Out of sight, out of mind. The Ocean has been a dumping ground for a long time. Do we know what kind of impact this might be having where this might be built. Close to shore is where most of the Ocean life resides due to more light reaching in the shallow water. There were proposals to build wind turbines in the middle on the Great Lakes. Not sure what happened to those. Maybe it can be done so it improves the environment, but that tends to costs more.

For a data point, the UK has a large number of offshore wind farms that contribute 13% of our electricity supply. On shore is 11%.

It's proving cost effective and sustainable. In some ways we are fortunate as we have a long history of offshore engendering with North Sea oil, the expertise there has translated well to offshore wind.

https://en.wikipedia.org/wiki/List_of_offshore_wind_farms_in...

Ocean currents often carry a lot of life around the ocean (https://www.cell.com/current-biology/pdf/S0960-9822(17)30077...). Hesitation is warranted, imo.

I don't see any way those turbines could affect marine life more than a ship. Probably less.

There's certainly no way to find out without building a turbine farm or two.

Everything depends on scale.

What are the upsides/downsides of water currents vs air currents here?

Is one more consistent than the other?

I imagine that water has more chunks to filter.

Water requires a smaller turbine.

..?

Another company in a similar space, although focused on tidal currents is Minesto.

The problem with wind vs. water is the extreme harshness of the environment. The only industry which has truly manage to tame the ocean is the oil and gas industry, and that at huge costs offset by the high value of what they produce. Not likely we will ever see anything like that in the renewable field.

No affiliation but an old colleague works there so see them pop up from time to time

https://minesto.com/

Salt, water, very strong forces, and a lot of things want to stick to it and build up layers of sand and organic material. And getting trained professionals that can operate in that environment is costly, slow and dangerous.

Beyond those, are there any additional problems from the environment?

The places with strong tidal currents have a tendency of limiting construction to ebb and high tide, in other words lot of expensive waiting around.

Regarding the environment, under the sea it is quite fine compared to stationary platforms operating in the north sea or Mexican gulf(hurricanes) year around, so that should be easier.

Another: https://simecatlantis.com/tidal-stream/

Water carries (IIRC) ~375x the energy of air per speed/unit volume.

Depending on the turbine design, you don't need to filter anything. The currents (gyre power) are far more consistent than wind turbines.

If not for the difficulties of siting, permitting, and maintaining subsea equipment, gyre power systems are far superior.

I've seen companies use wave energy before (1) but not ocean currents, but as someone else pointed out, the currents are a lot more powerful and consistent than winds so it makes sense.

I know Carnegie (2) talk up the fact that submerged equipment very rarely gets damaged by storms etc compared to floating or land based systems. (As long as they can keep fishing trawlers away and ban boat anchors in the area.).

1: https://www.offshore-energy.biz/carnegie-preps-new-ceto-desi... 2: https://www.carnegiece.com/

Water is stronger than air. This is a double edged sword; IIRC most tidal power projects have failed because the greater wear and tear is worse than the additional power generated. I would imagine the deep ocean magnifies this problem.

Not to mention, we do enough environmental damage to our oceans as it is.

Having the turbines submerged means stuff builds up on top of them. Eventually the blades have to be scrubbed or replaced.

Maintenance would be simpler than for offshore wind turbines, I guess. You just need to pull them up, instead of climbing up a pole. Maybe you don't even need to service them at high sea but just carry them to shore.

Predictability, with tidal power you know exactly (more or less) how much you will generate every moment of every day.

This energy partly comes from moon-earth oscillations.

Since geothermal, is this the first form of energy that is not even indirectly from the sun?

No, we also generate some electricity from tides.

I'd love to hear the numbers on these. I'm a fan of nuclear but the up front cost is massive. Smaller more modular production is easier to add incrementally. I would imagine nuclear is a better financial investment over the long term but that is only a guess.

Very promising to have a renewable that is more constant than solar or wind.

This will be very difficult to maintain. It has gigantic moving parts in salt water under high pressure. Blades would need to be replaced more frequently than wind turbines, which is a serious problem with wind turbines. What’s the plan for that?

Probably the last nail in the coffin of the (much more economically valuable) eels

This feels like we will end up with similar issues with wind turbines. Interrupted migration patterns and killing/harming marine animals coming near them.

Not sure how these turbines would interrupt migration patterns. Noise pollution maybe. But that should be smaller than that of a ship engine.

They shouldn't kill any macro fauna. It has to be evaluated in practice of course, but sea animals don't travel at speeds where bumping into something is fatal. If they bump into the blades at all, which move a lot slower than a ship propeller.

Kudos to Japanese scientists, always pushing the boundaries!

France tried years ago.

Incredibly expensive and inefficient.

I love the concept but it just cant compete with Solar , Nuclear or Fossil Fuel...

Just because something has been “tried before” in the past for something as critical as energy sustainability, particularly with the backdrop of climate change, doesn’t mean we shouldn’t try it again. If anything it puts us in a better position, with grater knowledge, in order to improve are chances of making it work.

As Edison put it about trying to invent the lightbulb: “I haven't failed - I've just found 10,000 that won't work”.

Except in this case we have the light bulb already in nuclear reactors.

It's like if Edison threw out the first light bulb that worked because it felt hot to the touch.

Interestingly, this whole technology might come to market more quickly than a nuclear reactor in an industrialized country could be build from decision to commercial operation.

At best, nuclear power is unwieldy, hard to calculate, needs a vast, highly specialized infrastructure and workforce and leaves you with radioactive waste with no solution realized as of yet. At worst, "impossible" accidents happen, people shoot at your reactor, nation states devolve and use the fuel for dirty bombs, somebody tries to blow the reactor up on purpose...

You hear about that tidal generator that blew up and contaminated 1000 Sq km of land? Ya, I didn't either.

Actually I have.

Just like we already had the “lightbulb” in the form of candles. There are significant downsides to nuclear reactors that other kinds of sustainable power might be able to address

During onboarding, the CEO told a story about how an employee's logic error caused a manufacturing plant to shutdown for hours. They of course corrected it, and production resumed, but the company was on the hook for millions in lost revenue.

Later that evening, the employee got a call from the CEO.

"I suppose you're calling to let me go."

The CEO replied, "Why would I do that after paying for a million dollar lesson?"

That's how I feel about nuclear.

> The CEO replied, "Why would I do that after paying for a million dollar lesson?"

That's a variation of something supposedly said by IBM's Thomas J. Watson, Sr.: “Recently, I was asked if I was going to fire an employee who made a mistake that cost the company $600,000. No, I replied, I just spent $600,000 training him. Why would I want somebody to hire his experience?” [0]

[0] https://blog.4psa.com/quote-day-thomas-john-watson-sr-ibm/ (which doesn't include a source for the quote)

In 200 years when the planet is on fire our ancestors will look at us and won't understand how we could have made such bad decisions. Yes, there is a (tiny) risk of nuclear disaster that makes an area uninhabitable, but thats (in my view) better than the whole plant eventually become so.

(I very much hope this statement is hyperbolic)

It's simply a false dichotomy that we have the choice between committing to nuclear energy generation, or catastrophic climate change.

We don't need nuclear energy. We really, really don't.

It's a tradeoff in the end, because the current generation of renewable energy is so much more expensive and involved than the equivalent in a nuclear energy plant.

I mean in my country, the energy grid is at capacity due to increases in demand AND production. It's very attractive to get solar panels installed on your house, but the grid cannot handle the influx of new production.

Whereas attaching a new nuclear plant to the main grid would be less of a headache.

>the current generation of renewable energy is so much more expensive and involved than the equivalent in a nuclear energy plant.

This may have been true 15 or even 10 years ago, but nowadays the exact opposite is the case.

> It's very attractive to get solar panels installed on your house, but the grid cannot handle the influx of new production. Whereas attaching a new nuclear plant to the main grid would be less of a headache.

How is that supposed to make any sense at all? The grid likes nuclear-flavored power better?

The grid prefers smooth, even, intertia-backed turbine-generated power to the choppy screams of a million inverters.

In order to avoid catastrophic climate change (hard to say we even can at this point) - we need anything we can get. Nuclear is part of anything we can get.

Following that line of reasoning. Considering we get 3-6x as much energy investing in renewables compared to nuclear then a single cent in invested into nuclear is an enabler of climate change right?

Does that include the batteries we'd need to have renewables take over the grid?

But we should be dumping lots of research dollars into both, even if we want 95% of the construction budget to be renewables.

Except scaling up starts to cost a lot more when you push it too fast, so we probably should be spending more than 5% on nuclear because it can work in parallel.

You're using a false equivalency fallacy though - that economics matter at all in this.

We need anything to get us to lower GHG emissions - regardless of cost.

Of course it matters. Money and people available to do the work is not infinite. Or do you disagree?

Therefore we have to optimize for the most impact possible. Is spending 3x as much as off-shore wind and 6x as much as on-shore optimizing for impact? Can straight up honestly claim that?

My issue is really the lack of progress with and utilisation of Nuclear over the last 40-50 years. In my opinion the anti nuclear movement resulted in extending the time we continued to burn coal. Quite right, at the moment the larger impact would be with renewables. However my original comment was not only in reference to decisions we are making now but also those of the last 50 years. If we had concentrated on using Nuclear, and not succumbed to the fear about it, we would be in a much stronger position now than we are.

It is simply economics. The anti-nuclear movement is insignificant but a very handy scapegoat. If nuclear made sense on a cost basis it would have pushed through somewhere globally. It's quite telling that not even authoritarian states, or very centrally controlled like France have managed that.

I agree that nuclear would have been preferable to fossil energy. But today renewables is way cheaper than either alternative.

You're using very poor arguments. A lot of whataboutism.

A meteor is coming to destroy the entire world. Do you sit around and wonder, "Is spending money on this really in the best interest of our shareholders for this quarter?"

Consider your example. You have two options proven to work by prior knowledge. Either renewables or nuclear at 3-6x the cost. What do you pick?

There's a statement in the previous paragraph doing most of the heavy lifting: "proven to work". This means no risk, why double invest?

We've already diverted meteors using both renewables and nuclear. Both work. Choose the cheaper option since it's not an one off event, it's an incremental change.

Every nuclear plant or wind turbine is negligible in itself. But the effect is quantifiable and known.

A robust electricity grid needs a variety of energy sources, wind and solar are great until it isn’t windy or sunny for a week. Are week long outages acceptable to you? Not to me. It is not inconceivable that a weather system results in calm weather with clouds for an extended period of time.

So other energy sources are necessary. Nuclear is another practical low carbon energy source and it is worth considering as part of the energy mix. There are many nuclear plants operating and under construction in the world. That they are uneconomic in some countries speaks more to those countries than to nuclear.

1. Geographical decoupling. HVDC connections are barely even newsworthy anymore.

2. Smart consumers. Electrified transports are perfect where you can shift the charging to any point in time it's not actively driven. This without having to pay the round trip efficiency loss since charging the battery is valuable work.

3. Better utilize hydro to compensate for the last bits of intermittency left.

We're so far from a grid where large scale storage would be necessary that dwelling over it and putting forth nuclear as the only solution is ridiculous. You could make hydrogen from your renewable energy and then later burn it and still come out ahead of nuclear. That's how uncompetetive nuclear is.

Permitting new power lines is difficult. Here [0] is an example of a project stalled due to opposition. It is unrealistic to think that someone is going to pay for transmission lines to get built with excess capacity most of the time in case we need to send power from one coast to another. Building power lines is expensive, battery storage is also expensive, so if you want to promote intermittent generation sources far from loads simply add those to the cost when comparing to other sources to make a fair comparison.

People will mostly all charge their vehicles at night, so it won’t be from solar power. Unless the solar has battery storage, in which case we are charging batteries from batteries, which is inefficient.

I’m not sure why you think there is a lot of flexibility in the existing hydro power, there isn’t that much of it and it is often constrained by having to keep rivers flowing or saving water for peaks.

My point about nuclear is that it is competitive in other countries, the problem is that North America can’t competitively build it any more not due to technological problems but political and managerial issues. Imagine global warming could have been avoided by getting really good at building nuclear plants. Look at how much imaginary money has been printed for less catastrophic problems. We could have done it, we still can. Nuclear is uncompetitive because we have somehow made it so here.

a robust grid needs a variety of energy sources, Arguing against any low carbon source is counter productive to me. There is always going to be a need for generation with a characteristic like nuclear power.

Edit: I should also add hydro projects in Canada such as muskrat falls and site C are costing 10-20 billion which I believe is similar to nuclear and also taking a decade to finish.

0: https://www.cbc.ca/news/canada/montreal/maine-supreme-court-...

>People will mostly all charge their vehicles at night, so it won’t be from solar power.

It always amazes me that people assume that.

Take a 3 car household. Lets assume every one is a Tesla. Just for ease of calculation.

To charge a Tesla in 8 hours, one needs a 240v level 2 charger. This is the same type of connection one would need for a washer/drier/oven/stove.

Per car.

Now. You've about doubled the number of high pull outlets in the average home. Most people [sans shift workers] work during the day, and there are only so many hours in the day for people to charge. 3 Teslas could in theory be charged back to back off one outlet, but now you have a nightly ritual. I assure you, people will go for the parallel charge.

Now expand this load to neighborhood scale. Now propagate that to the trandmission infrastructure.

This is not as easy a thing to accommodate once you start sitting down and actually tracking the numbers.

So you think there will be two cars charging at night per house instead of 1?

As long as people aren’t also using their oven and running the drier I don’t see that it changes much for required transmission and generation capacity, but there would be more energy used at night than we currently see.

The more you can use, generally the more you will. And people really discount the drain of say, an extended family who all have to charge vehicles for work the next day.

It's not a pretty picture.

Meh, I’m not seeing a capacity problem. Either their panel can handle the load or it can’t and then they have to upgrade panel to higher amperage, and if the whole street upgrades their panels then the utility might have a problem.

I think the main problem is going to be that we are going to need a tonne more energy to replace fossil fuels and the daily demand curve with the diurnal pattern is going to flatten right out as people charge all night.

Likely they will be more puzzled by our focus on increasing energy production in the vague hope it will quickly displace most oil/gas production and use, instead of capping co2 emissions.

sometimes the lesson is "don't concentrate radioactive isotopes, you haven't developed the institutional incentives to contain them reliably, and will eventually experience terrible disaster"

Hope those don't create whaleburger or giant squidburger. Which will be out-of-sight-out-of-mind unlike the visible bird deaths aboveground.

Whales don't usually run into things except on purpose. And even if they do, they aren't as fragile as birds...

> the visible bird deaths aboveground

And which have been vastly exaggerated.

This is such a tediously nonsensical interjection:

...laying the groundwork for a promising new source of renewable energy that isn't dependent on sunny days or strong winds.

How many times does it need to be said that any reliable energy system run entirely on sunlight and wind absolutely has to incorporate storage? Storage can be electrical (short-term supercapacitors for buffering high-frequency variations in windfarms), electrochemical (batteries, and since portability is not an issue, there are many options for grid-storage batteries besides lithium), chemical (using electrical current to drive the formation of hydrocarbons from CO2 and water, aka artificial photosynthesis, and similar conversions), or mechanical (pumped water storage, rotating heavy masses, air pressure in caverns, etc.). That about covers the range of storage options I think.

I don't know what to think about people that trot that one out over and over again but to be charitable I'll just assume gross ignorance at this point, rather than deliberate deception.

Because incorporating storage into the story also means brining in the cost. Many of the solutions are not cheap, dependent on specific geology, and / or have their own large carbon footprint.

The only thing that solar and wind bring to the table is being very cheap, but you need to compare apples to oranges for them to stand up to other solutions.

Edit: this is regional specific, but wind and solar are worthless for one to two months a year where I live - rarely much sun or wind. There's simply not enough storage to power much of anything for that long, so even with cheap storage, it's worth having options that don't rely on weather.

Of course, we are nowhere even close to an ocean, so this tech isn't it, but keeping exploring options is nice.

solar and air-conditioning. Energy consumption correlates with production. A match made in heaven.

You're demonstrating my point. Solar and wind are useful for cheap green peak power if the peak coincides with weather- a best case scenario that varies by region.

Grid power supply needs to be robust enough for worst case (or even just normal bad) scenarios, or else people die.

You are clearly in wrong here. There's a reliable energy system run entirely on sunlight, that is basically identical to the proposed deep ocean currents in the principle: hydropower. In short: the storage is built-in - it is in the potential energy of that small percentage of the water in the oceans, which is still large enough to be absolutely immense.

Storage is kind of the major blocker for those technologies currently.

Most countries (if not all?) are still far from the point where storage "blocks" solar/wind. But moving forward, more storage will be needed. And I am quite optimistic that it will be there as soon there is enough energy to store in the first place. Some of it will come anyway, as electric cars make for great storage. Switching cars to electric doesn't only directly reduce CO2 emissions, they are a great way of storing surplus electricity and also drive the cost for battery storage down.

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