Since the number 1.2MW didn't mean much to me, modern on-shore wind turbines seem to supply 3-4MW and offshore ones 8 - 12MW.
But this seems a lot easier to transport and install compared to cranes and the nightmare of navigating turbine blades on trucks through places. And if these hold up to water and don't cause too many problems for wildlife, there would be a lot less discussions about these "messing up my skyline", while tapping a new source of energy.
There were a meta-analysis regarding population of birds in areas with/without wind turbines, found no statistically significant difference (unlike coal, where difference was huge)
Like much statistical analysis there are some details that might not be well captured. Much of the opposition to wind power based on bird deaths is caused by the Altamont Pass facility which is placed in a golden eagle breeding area and has significantly disrupted that species. There could be similar risks here if generating equipment like this were to be used in sensitive marine habitats such as the Monterey Bay. It will probably be worth ongoing study to avoid potentially serious problems that broad statistical analysis may not catch.
Yeah, if you're looking to save the birds, the first order of business is to ban cats, because turns out those cute little guys are rather adept at bird murder.
Apparently that isn't true and just shifting the blame away from the pesticide and agricultural industry which have decimated insect populations. Which are the food source for many birds. Much like blaming consumer's personal choices for CO2 emissions.
"We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals." https://www.nature.com/articles/ncomms2380
This is the first time I've seen the statistic quoted with the distinction that it's about feral cats, and it makes a heck of a lot more sense now than it did when I had the impression they were saying the cats I've had, which were on the whole utterly useless at catching things, were secretly massacring birds by the dozen. Thanks for the drive by enlightenment :)
I have no doubt that stray and feral housecats in the cities and suburbs are killing great numbers of common house sparrows, but the things that are driving down numbers of endangered birds in rural and remote areas (where feral cats are not a problem) is habitat loss and the decline in food sources (ie. berries and bugs).
Feral cats are extremely common in rural areas (though not in remote areas). Ask anyone who's lived on a farm or ranch about "barn cats".
Regardless, "the single greatest source of anthropogenic mortality for US birds and mammals" sounds unambiguously not great, even if they're mostly not endangered.
How significant is that number? Is it large or small? How much of it is offset by larger populations of well-fed birds and rats in cities? In many countries, people specifically feed stray cats to keep cities rat-free, and predatory birds are often used for pest control (huge crow flocks terrorizing parks etc).
Yep. I mostly meant for or rather caused by this kite. I wouldn't expect it intuitively, as it's just a big object in the water, not moving erratically or obstructing anything.
It has a 39-foot wingspan and moves in a figure 8 pattern on a seabed tether. There's going to be at least some implication for local wildlife, but is it worse than the impacts of fossil fuels? I have no idea. It's definitely an interesting concept. I'm sure it will get more efficient and require a smaller footprint over time, assuming we invest in it.
If tidal energy takes off, I'll guarantee you that - if it hasn't already happened - there will be chilling articles about dead fish and other sea populations.
Actually, these seabed moorings can create rich, local eco-systems. I know local fishermen here in Maui are drawn to areas around the off-shore buoys...
A kettle uses ~1.5KW, a geyser ~2KW, an oven ~5KW, a stove about ~3KW. These are fairly high estimates I got from some quick googling. If you add these all up, and account for some more appliances (HVAC, fridge/freezer etc.), I think it is safe to estimate that a household less than 20KW at peak, even though it is a fairly high estimate.
So going backwards from there, 1.2MW = 1200KW and 1200KW / 20KW = 60 households at peak usage. Which is a very conservative estimate.
For future reference I will use 1MW = 50 households as a conservative rule of thumb. Maybe 100 households per MW is closer to reality, but that feels fairly lenient to me.
If the average home was using 10kW constant it be using 240 kWh a day, which is enormously high.
In terms of average usage an average sized home in the US is much closer to 50kWh a day, so roughly 2kW average demand. That would mean 1 MW is enough for 500 homes on average. The one thing that doesn’t is peak demand load, say when everyone gets home from work and turns everything on at the same time or a particularly cold or hot day.
Edit: the average US home uses just shy of 1000 kWh a month, or just over 30 kWh a day.
According to to stat.gov.pl [1] the average Polish household uses ~24.6 GJ of energy annually per 1 inhabitant. That's 6800 kWh annually per 1 inhabitant.
According to eia.gov [2][3] the average US household uses annually 56.6 million BTUs of natural gas and 10500 kWh of electricity. 56.6 million BTUs is 16600 kWh. That would bring the total to 27100 kWh.
But wait...the Polish data is per inhabitant. The average number of people per household in the US is 2.6. Dividing 27100 by 2.6 gives 10400 kWh. Alternatively, the average Polish household is 2.47 people, which would give Polish per household usage of 16800 kWh.
The US does appear to use more energy per household (total or per inhabitant) than Poland, but by a factor of about 1.6, not 5.
Finland is probably like 15000 kWh/year/house (for a new house more like 10000 kWh/year). All the heating of the house & water is done by electricity, though.
Ok, but what do you actually use? I have a very small 3-bed house in the UK, and over the last few months we've been averaging 1100-1200kWh of electricity per month(and we heat using gas, although we do have an electric car).
Last month I used 1402 kwh in Washington State, which is high for me.
2600 sq ft home kept at 71f, electric heat pump, & heat pump water heater, but I had a few holes in the walls for several days due to repairs during the coldest month of the winter so far which messed up my average using electric heaters to backfill the gap.
Obviously, the holes were covered over when not being worked on but it wasn't as air tight as compared to buttoned up and fully insulated as usual.
My power consumption is usually 30 to ~75% of that depending on weather and activity.
Also relevant, houses aren't boiling a kettle and running their oven 24x7, so this is more like worst-case peak load and will be spread across different houses. Having some kind of battery storage closer to the houses will help a lot - the tidal generator can run fairly constantly and fill the battery, and the houses can draw in short bursts from the battery.
Yeah. I always feel that the solution for clean and abundant energy globally is to start with better energy grid management (and storage). There's already so many fit-to-all-geography solutions available. It's just that current grid is used to supporting lines centralized around big energy plants and not small producers.
I also always feel that there's a lot more to take down from energy consumption per household by simply making more efficient devices (especially for heating and cooling). It's possible that modern AC/heaters are already close to the peak electrical efficiency, but I guess even better producer standards for things like insulation, thermal conductors or precision sensors could still squeeze something out of the nation-wide usage.
I think 100 households per MW in milder climates is very conservative.
Anectdata: I have a ~150 square meter, 50 year old house heated by electricity and heat pump. I live I Norway, and where I live winter temperatures usually don't get lower than -12C. I have 2 EVs that are driven around 50k km a year combined, charged at home every night, simultaneously.
I peak out below 15kW (1h average). That number is deliberate since I get a higher tariff if I go above 15kW. I have some minor smart house installations that most significantly cuts power to my hot water heater if I get close to 15kW, but even without that I would rarely get above 15kW, and never above 20kW.
Average power this January was 4.75kW, December was 4.96kW, August was 2.25kW.
From top of my head: my grandma used to have one. There was always a little flame running for safety in case of leaks, but when she used hoy water, I think the geyser just heated it on the go, instead of preheating a reservoir.
A device for heating water on-demand, usually a gas burner with a spiraling water pipe surrounding/above it. As opposed to a boiler, which pre-heats water and stores it for later use (and also needs to keep reheating the water as it cools if not used).
A common blocker for offshore wind is people* complaining about seeing wind turbines on their formerly immaculate horizon. These don't have that problem.
*: e.g. Ted Kennedy. Rich and politically connected people like to live on the coast
What's interesting is that we can stop off-shore wind projects for that reason, but can't seem to stop the advertising barges that run up and down the coastlines.
> In April 2022, Minesto announced a detailed plan for large-scale buildout of tidal energy arrays in the Faroe Islands. The large-scale buildout plan sets out a stepwise installation of tidal kite arrays, each with 20-40 MW installed capacity, at four verified locations.
> modern on-shore wind turbines seem to supply 3-4MW
That sounds like the very largest of the most recent wind turbines. I think most of the in-production wind turbines people are used to seeing these days are closer to the 2 megawatt range.
Another reference point: the coal plant in my area outputs 2.3GW. It would take almost 2,000 of these tidal kites to match that output.
I just don't understand why we spend so much time and money on renewables like this when Japan has an 8GW nuclear plant. If the US focused on building these en masse then we'd be in a great place.
Because a lot of people hate nuclear energy, and don't support building new plants. So it's not really a choice between nuclear and renewables, it's a choice between renewables and fossil fuel power plants. Besides, I think there's definitely a benefit to decentralizing the power grid, and to learning how to tap different energy sources. I imagine that there are places in the world where nuclear is not appropriate, but tidal energy is abundant.
More renewable is good.. but there is always one fear in my crazy mind about these: This isn't actually renewable but taking energy out of a huge reservoir (Same for solar if pea counting, but solar is really endless until the end of the solar system).. and if we'd scale it massively the result could be another catastrophe. (Same btw. with geothermal?).
(Btw.. I maybe got tidal wrong, so if it is just taking energy from waves via wind this counts as endless solar. Still, consider systems which would really break the tides and take energy out of the earth<=>moon system).
The answer to this fear is that this reservoirs are so massive they are quasi endless in regard to what we ever could take out? It is hard to find numbers for these crazy thoughts :)
Some numbers here: https://en.wikipedia.org/wiki/Tidal_power#Principle (last paragraph). Tidal energy is wasted by natural coastlines all the time, being converted into heat and erosion. If this effect is constant, it looks like the day gets longer by 7 minutes 12 seconds every 36.5 million years. (I calculated that because it's a 1% reduction in rotational energy.) Human extraction of tidal energy is much smaller than the energy wasted by tides acting on all the world's coastlines, I assume. To some extent it takes energy away from coastal erosion, which also seems fairly benign.
For a detailed discussion of “what is the environment, and what does preserving it look like?”, see the Red Mars trilogy. Very interesting questions about nature as aesthetic vs nature-in-its-own-right
Erosion makes gravel and sand, which are quite useful. It also makes minerals and nutrients accessible to life.
But we spend a lot of time and money managing erosion, and at the same time (often accidentally) create lots of erosion in other places. I doubt extracting tidal energy will have effects on a global scale, though it might cause some local changes
It's good that you are aware it's a crazy thought :) Nothing wrong with looking into it though. Wikipedia offers:
> Movement of tides causes a loss of mechanical energy in the Earth-Moon system: this results from pumping of water through natural restrictions around coastlines and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since its formation. During the last 620 million years the period of rotation of the Earth (length of a day) has increased from 21.9 hours to 24 hours;[10] in this period the Earth-Moon system has lost 17% of its rotational energy. While tidal power will take additional energy from the system, the effect is negligible and would not be noticeable in the foreseeable future.
and there is some simple math in the [Tidal acceleration] page [0] that you may want to read. Basically, the tides slow the rotation of the Earth, with some of the energy being transferred to the Moon but most of it going into friction. The natural friction is estimated at a (surprisingly low, IMO) 3.64 TW, and at this rate the Earth will stop rotating in 50 billion years, long after the Sun has blown up.
So if we want to keep the Earth spinning (albeit slowly) until the Sun goes red giant, we can afford to cut that time down to a tenth, meaning we can produce 36 TW (before conversion to electricity, i.e. ignoring efficiency).
If we are being reckless and just want to use power until we figure out nuclear fusion or something better, let's say a million years or so, we can make some 180 PW from tides. But since it would almost all turn to heat, and since that is more energy than the Earth gets from the Sun, that would probably be unwise unless we find a way to get it off-planet with very high efficiency.
(Global electrical energy production is currectly about 28 PWh per year, equivalent to a constant 3TW or so.)
> If we are being reckless and just want to use power until we figure out nuclear fusion or something better, let's say a million years or so, we can make some 180 PW from tides. But since it would almost all turn to heat, and since that is more energy than the Earth gets from the Sun, that would probably be unwise unless we find a way to get it off-planet with very high efficiency.
I think you're touching on the problem very nicely here: the problem is not "how much raw energy is there" (because there's an absolute fuckton of it) but "when does the impact of capturing this energy - thus removing it from a complex ecosystem whose stability may depend on it - and turning it into something else - thus adding to a complex ecosystem in other ways - becomes a problem", which may or may not come well before the theoretical raw energy cap.
I'm not sure those considerations are applicable. There is no "ecosystem" that depends on the rate of slowdown of Earth's rotation - we do need to leave some rotation to keep flora and fauna alive, but that's a "reservoir" problem, to use the OP's formulation, not an intensity one.
As for the addition of energy (heat) to the planet, sure, but there's nothing specific about tidal energy here. All energy sources except solar (and wind/hydro which are direct solar derivatives) add heat to the planet that would otherwise have stayed sequestered. But it's many orders of magnitude less than the heating from solar energy, which is why increasing Earth's absorption factor by a few points is an infinitely bigger problem than all the energy we are directly producing or can hope to directly produce in the next few centuries.
Also worth noting that trying to extrapolate the effects of current technology at this timescale is pointless.
There will be tide changes in human’s technological capabilities long before there could be any reckoning for over-extraction of the Earth’s rotational energy.
For example, in our ability to bring mass into orbit. Add a couple orders of magnitude in that capability, and humans can start directly tuning the Earth’s total solar irradiance by shooting lunar dust into a Lagrange point, reducing the amount of sunlight hitting the Earth by fractions of a percentage.
The Lagrange point is not perfectly stable, so the dust naturally dissipates over a 10-20 year timescale. If you don’t keep sending more dust, the “planetary sun-shade” naturally dissipates, so there’s zero risk of overdoing it.
Basically, within the next ~50 years, I predict we will gain the ability to turn down the planet’s thermostat in a very safe and predictable fashion, without having to pollute our own stratosphere. Overheating the planet becomes a total non-issue.
With all seriousness, I’ll throw in “the unexpected breakthroughs in intuitive AI will aid this effort.” I sincerely think that LLMs will at least make R&D cheaper.
Beyond that, “we haven’t been to the moon” isn’t a fair summary of our tech imo - a HUGE portion of that is political in origin, and private companies have invented reusable rockets which is pretty damn important
I sincerely think that LLMs will at least make R&D cheaper.
How, exactly? Because to me it's just as likely that LLMs will hallucinate alternative solutions based on their flawed world model which will send numerous unfortunate researchers on wild goose chases that turn out to be exactly that. And I expect the volume of impossible-yet-probable-sounding solutions will dwarf the actual costs saved by using an Automated Induction system.
Long story short: every engineer and scientist in the country will suddenly get 100 interns. Will they make perfect work? Hell no. But current levels of Intuitive Computing LLM tech can be extended to much higher levels of autonomous/agential behavior, and that’s all you need to bring computers from a tool to a partner.
Your criticism of an all-in-one induction system / Reasoning Engine is well founded, no disagreement from me. I just think that they’ll be able to help in myriad, smaller ways. Finding synergies, analyzing data, designing and employing frameworks/simulations/tools specific to the researcher’s work, and just generally being a bank of knowledge that can be easily browsed through complex linguistic filters.
IMO :) I am an optimist. Maybe it turns out chatgpt is the best we get, in which case I’m very very pessimistic about our chances of meaningfully solving climate change, rocket-launched-lunar-dust or no. So… I have a “fingers-crossed” based leap of faith in my reasoning somewhere
> There is no "ecosystem" that depends on the rate of slowdown of Earth's rotation
I mean, raise acidic/temperature levels only so slightly and it kills off coral reef, which in turn destroys fauna that depends on it, leaving huge areas barren.
What I'm getting at is that small changes can have dramatic domino effects. Mass-scale tide dampening could have unforeseen effects.
Not saying any of the solutions are going to be a problem, merely that it's better to ask crazy questions about what happens when they ramp up at scale than handwave things away with uniform spherical cows.
> at this rate the Earth will stop rotating in 50 billion years,
That's not what the link you posted says. It states that that's when the Earth-Moon system will be tidally locked, so that the Moon orbits the Earth at the same rate that the Earth rotates around its axis.
Kind of if the earth slowed so that one "day" took the equivalent of 28 days now. The earth would be locked with one side always facing the moon, so there would be no tides, but it would still be rotating. Except it will end up be a longer "day" than that, because as energy is transferred to the Moon its orbit is raised, which slows it down.
Ignoring for a second both the human factor and the Sun having gone red giant much earlier... I wonder what kind of ecosystem that would create. If the Earth were tidally locked to the Sun (which is what I was picturing in my confusion), it would clearly end up as two deserts with a tiny strip of life along the twilight circle. But how would complex life evolve to adapt to a 28*24h day/night cycle? We do have decently-sized ecosystems in caves so long nights aren't insurmountable, but being baked to really high temperatures for a month and then cooling down to freezing for another month sounds like quite a challenge.
This is nice and all, but in 50 billion years, the moon's distance from the Earth will much greater which means it's gravitational effect on Earth will be much smaller.
OK. Do you have any reason to suspect that the people making their calculation didn't take that into account? Of all the things that will vary over time, including the distance between the Earth and Moon, do you really think they'd have missed the fact that the Earth's gravity varies with distance?
If you've got what you think is a more accurate number, and can show your working, I'm sure the wikipedia editors would be willing to take a look at it.
You’re right that nothing is unlimited. Luckily in this case, the energy of waves and tides is given to the oceans mostly by the gravity of the moon pulling the water as it passes overhead. Also a little bit by the wind which is fed by solar heat energy. The moon is slowly moving away from earth and eventually, in hundred of millions of years, it will impart significantly less energy into the tides.
The energy that the moon gives the tides is essentially the same as how the sun gives energy to the ground with light. That is to say: If we don’t collect it, it just gets turned into another kind of energy that is absorbed by the environment. For tides and waves that would be mostly heat, and a little sound. And most of that heat would eventually be radiated back out into space.
So suffice it to say, while there is a finite pool of energy stored in the tides, it is so massive we could never make a difference, and it gets recharged everyday by the moon.
It's good to do the math and think about the big picture sometimes. ;)
p.s. i tend to feel somewhat skeptical about a lot of renewable projects i read about in the news. And even if the math all works out and it really IS The Best Solution i cant help feeling we are ignoring the elephant in the room(population growth). Maybe human beings should start preparing themselves to live with less(and be happy with that).
Even if that were true (and it won't be for another 5-6 decades using current predictions at least), energy consumption is anything but. And if there is a risk of electricity usage plateauing, they'll just find something new like training AI models or spinning GPU's to churn out digital money (where said churning is entirely artificial).
After reading a bit of the comments thread above, i couldn't resist adding a bit more.
> The single most important assumption in this paper is that energy consumption will increase by 2% per year.
Quick reality check: 1.02^1000years = 398,264,652x increase! This could potentially be an unrealistic projection. Let's consider what we know from the article(and google).
Here's a few numbers pulled from the article for reference:
~1.73 x 10^20 J tidal energy lost per year naturally
5.67x10^20 J was the total global energy consumption in 2013(10^18 is 1%)
So 398,264,652 x 5.67x10^18 J = 2.258 x 10^27 J! That does seem like a lot. In comparison total sunlight absorbed on earth's surface each year is roughly 3.85 x 10^24 J.[1]
> It might also be that tidal energy extracted by humans, comes out of some fixed 'budget'
So lets compare that to what is already being consumed and think about what amount of energy generated might be realistic. Top google result tells me global energy consumption is about 5.80 x 10^20 J2 these days.[2]
I guess the next question is what would be a realistic upper limit for the amount of energy we could harvest globally from the tides? Referencing the Stanford article again, we have an estimated annual energy loss of 1.73 x 10^20 J total from natural friction of the tides globally. Is it realistic to think we can harvest an equivalent amount of energy for the grid? I wonder what sort of impact a turbine project that size would have on the earth? Is it even possible? For sake of being rational, let's say we think a network of turbines 1% of that size(10^18J) is potentially possible. How many turbines might you need to make for something that size?
So lets take the kite-turbines from the article at the top. Each one of the produces 1.2MW. Does that mean it produces 3.78×10^13 J annually? Or is it closer to half that(1.89×10^13J)? In a 10^13 J ballpark we would need to produce about 10^17 to approach our max limit 10^20 J harvested. Correspondingly a project 1% the size still needs 10^15(a quadrillion) of these turbines globally. That seems like a lot and it just sort of seems in my mind(maybe i'm wrong) that there would be some sort of environmental impact. Also, now that you have shrunk your project the total energy produced is now a fraction of 1% of the current total global annual energy consumption, and grows more insignificant every year consumption rises.
Not sure I agree that population growth is over, but isn't it true that energy consumption per capita is also increasing? Either way I think we still have the realistic expectation of continued 2% growth in global energy consumption for the next few decades at least, doubling every 35 years. Unless we can find ways to harvest larger quantities of tidal energy without breaking the ocean it just doesn't seem like a silver bullet to me as far as climate goes. Assuming we could harvest 25% the quantity of what occurs naturally, that only gives us 0.4325x10^20J annually, which is only 7% current global consumption - in 35 years that number will only equal 3.5% of the total consumption. I guess it's a question of how much you want to screw up the environment in order to save it.
TLDR, saving the planet with tidal energy seems kind of misrepresented imho. Build wooden megaliths instead. ;)
How would solar be the same? That "reservoir" is emptying wether we hold silicon into the photon flow or not. Tides and wind aren't quite as far from just taking what is already disappearing, but even there: the natural drag of land and sea floor shapes is not only so many more orders of magnitude larger than anything we could ever build, there's also the nonlinearity of drag, if we slow down the natural flow a tiny little but the effect of natural drag will decrease accordingly and the total difference to natural flow will be much smaller than it would be if drag was linear to speed.
Tidal energy comes from the moon (and the sun) pulling the oceans as the Earth spins. Extracting energy from this effectively increases the drag between the ocean and the land, which slows down the rotation of the Earth. This effect even occurs without extracting tidal energy, and some of the dinosaurs (IIRC) had 19 hour days.
The amount of energy in the rotation of the Earth is so huge that this basically doesn't matter, 10
TW for 660 million years, which is into the realm of "will too much carbon be subducted for photosynthesis to continue?" timescales.
A. Build some huge-ass rockets on the moon to accelerate it to offset any slowdown from changes in tidal energy.
B. Divert a few billion tonnes of asteroids to crash into the moon's aft, adding both to the moon's velocity and mass.
I believe that if we begin working on any of these solutions within a hundred thousand years or so from now we should be able to offset most of the projected long-term lengthening of the day.
You'd have to put the rockets/target the asteroid impacts on the Earth, the effect on the Moon from this interaction is to push it into a higher orbit to conserve angular momentum of the combined Earth-Moon system.
You're edging on the laws of thermodynamics there: on a long enough time scale all energy is non-renewable, every little bit of consumption gets you that much closer to the heat death of the universe. But given the vast reserve in that system for once humans won't be able to meaningfully affect it unless we start consuming far more than we do today. Interesting aside: that momentum is a giant energy reserve and conceivably you could rob some of it to create a means of escaping the gravity well even if there had not been any other.
> Same for solar if pea counting, but solar is really endless until the end of the solar system
Imagine you wrap the Earth inside a sphere of perfectly efficient solar panels, that would be energetically troublesome! Every bit of solar panel we lay removes a bit of that overall energy flux; the question is then how much can we afford without detrimental impact.
Essentially we dampen tides with these devices. Windmills are slowing the wind. How much can we afford before it has an actual detrimental effect?
Also, pedantically, "renewable" is a fun word.
The question of "renewable" is whether the energy/matter somehow gets back in some way... Of course there's entropy and such.
Say you cut wood (CHO) and burn it. If you grow enough wood it'd recapture H2O+CO2 and you have a nice endless loop (plus entropy). That would presumably be renewable.
In that sense (again, pedantically):
- nuclear (and so the sun) is not renewable: reversing U/Pu/whatever fission is a teeny bit out of our league so someday the supply will dry out. Fusion as we do it (and the sun too, being main sequence) is H->He and we don't exactly know how we could reverse that so someday the supply will dry out.
- fossil fuel is renewable... on a geological timescale, which is not really practical; we can't exactly grow big enough forests and bury them for millions of years to get fuel back. So someday the supply of humans surviving will dry out.
- tides/wind is not renewable: we get mechanical energy but don't return it to the original place (or maybe extremely indirectly in the form of heat)
So it's all named backwards!
Or really there's no renewable... Essentially it all pans out because the Earth is not a closed system, there's loss in every transformation but it's balanced by the energy influx from our nearby star.
So I guess the "renewable" thing is not really, it's more like "capturing energy from an astoundingly immense and complex system in a way that doesn't throw it in a runaway catastrophe one way or another before the sun exits its main sequence".
Nuclear isn't renewable, but there's a huge amount of it and it doens't have the same problems.
> (and so the sun) is not renewable:
The energy we get from it is. It's not a fixed resource that we're depleting. When we burn all the coal, it's gone. Tomorrow there will be more sunlight. We're not cutting chunks off of the sun to get energy for solar.
> - fossil fuel is renewable... on a geological timescale,
Only some of them, and only if we change the definition of renewable. Coal is there because there weren't fungi that could break down lignin at the time.
> Imagine you wrap the Earth inside a sphere of perfectly efficient solar panels, that would be energetically troublesome! Every bit of solar panel we lay removes a bit of that overall energy flux; the question is then how much can we afford without detrimental impact.
We could probably benefit significantly with reducing the energy flux right now.
> I think you're assuming renewable means infinite.
No, for the purpose of this dumb exercise of mine, I mean the resource we use for energy production is replenishable.
> It's not a fixed resource that we're depleting.
What I mean is that the Sun is going to exhaust its H supply. We just happen to harvest part of its output, but it's depleting itself whether we harvest it or not, so we might as well do it :shrug:.
So at our scale it looks like infinite but in the strictest sense it's a consumable that does not replenish.
Fundamentally that makes it not different from nuclear fuel (whether heavy fissile ones or hydrogen if we manage fusion someday) which as you mention are in ample supply, yet we consider them to not be renewable while the sun would be? The only difference is a) the Sun is (much) bigger thus will last (much) longer and b) we delegate fuel logistics and fusion reaction to the sun.
But then again, trees are not really renewable, they got to get energy from somewhere to grow... IOW they're essentially CHO-based solar batteries.
As I said, I was not trying to make any point, just being extremely pedantic about semantics for fun ;)
> the definition of renewable
> A renewable resource (also known as a flow resource) is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale. When the recovery rate of resources is unlikely to ever exceed a human time scale, these are called perpetual resources
Essentially the definition is focused on resource when it's really about time (esp. our extremely small time scale vs stellar scale). The resource in reality doesn't replenish, rather it's so huge that we can consider our usage of it well below rounding error. IOW from our very small "rounding error" human point of view it might as well be considered infinite.
Yes, you're right. What you're doing when harvesting tidal energy is introducing a friction like resistance on the moon as it revolves around the earth and on the rotation of the earth, and taking energy from it's energy of motion, that is, slowing it down. But I'd expect with the masses and velocities involved that this amount is miniscule and not even close to being measurable. That said, we didn't think we could impact the earth by burning fuel, and if something like this were adopted large scale the impact could surprise us and be a real problem.
Solar isn't as limitless as you'd think. It is limited to the surface of the earth, more precisely, the surface area of the 2 dimensional disk from the perspective of the sun. And on earth, that's what drives life, so harvesting solar energy on the surface is something that, if deployed beyond what we think we need right now, can have a negative impact on the earth. Harvesting it in space and beaming it down would heat the earyy up too, as the energy is used it produces waste heat which means on a large scale even using the energy on earth would have a negative impact.
Alien archeologists from the future: "Earthlings caused a catastrophe by trying to suck every bit of tidal energy. Via tidal acceleration[^1], they made their natural satellite fall into their planet. The curious thing is that the kind of planetary technology level they deployed to extract energy from the tides was more than enough to build huge rotating habitats, which they even knew of and called O'Neill cylinders[^2]. But Earthlings called names anybody proposing the idea, and it never really took off before their moon fell on their heads. This is a textbook case of how a civilization's culture affects their development."
Like two whole percent goes to cracking puzzles, and if you prove you crack those puzzles we let you buy things. Those puzzles? Guessing hashes for Blockchain. Not cancer or science or engineering, just automated planet wide gambling.
Then how much is used for ads? Like top to bottom, serving ads. Must be a ton. As a planetary anthropologist, seeing how much infra we built to watch people do silly dances or say things on TikTok... Like we're so addicted to ourselves that we built all this to watch ourselves do things.
I get your point with blockchain(altough i'd like a source for 2% of the entire human energy production going into it) but ads are useful actually, they make people know about what other people do which drives economy, and economy is basically a fancy word for the system that distributes each human's limited time into the various tasks society needs(which do include large scale planetary development but also for example, your local supermarket which makes you eat).
As for tiktok and silly dances, humans don't need only food and water to work reliably, they also need mental health. So leisure, amenities, relationships etc.(yeah tiktok included) are an addiction in the same sense food water and oxygen are an addiction, we just need them to work.(obviously while "addiction" to leisures is in general not a real problem, addiction to a specific thing in this list is, just like addiction to a specific food is a problem. I'm not saying tiktok addiction is a good thing)
If you think humanity's purpose is to develop their knowledge of the universe and techonological grasp, then i reassure you that(almost) everything we do on this spinning ball is a cog in the machine that ultimately sustains that development
> economy is basically a fancy word for the system that distributes each human's limited time into the various tasks society needs
That's a bit too idealist a view for me. The economy isn't strictly or even mostly about fulfilling needs of society, but the aggregated demands of those with economic power, both wants and needs. A lot of what we spend effort on is not useful to society and a lot of needs go unmet. Certainly not every wasteful activity can be waved away as investing in our mental health. Some leisure is a net negative there, too. Some spending is destructive, with no upside. We humans are only somewhat-rational actors.
the tidal systems are insanely vast and powerful. the gravitational pull of the moon and the sun is so large that even if you deploy a massive amount of kits on a small surface, you're unlikely to have an impact on the tides. theoretically it's possible, but it'd require an implausible scale of deployment
in the past twenty years the plains states like kansas and oklahoma began having earthquakes due to injection of petroleum wastewater into the ground. The government had to stop them because private industry literally does not care what gets destroyed
The sea is a harsh environment, but the energy it contains, in the form of waves (basically concentrated wind) and tides is enormous (partly thanks to the density of water.)
Of course, like with all renewable, location matters. But there are lots of places with strong tides, and lots of places with reliable waves.
Harvesting this abundant energy at scale, with reasonable maintenence costs will be the next breakthrough in green energy.
I've often thought why not dam a whole estuary or bay and use hydro to collect the energy on the the fall and rise of the tide. I know the environmental impact wouldake it unpalatable but are there any reasons it wouldn't work?
This is interesting–it made me wonder if this had ever been considered on NYC's East River, which is a tidal estuary with strong currents. Turns out there's been a company working on it for a while, with free-moving turbines rather than something that spans the whole thing: https://www.energy.gov/eere/water/articles/tidal-testing-und...
Meet project Atlantropa, a proposed plan to dam the Mediterranean (or more accurately the atlantic ocean) at the strait of Gibraltar. A project so absurd and gigantic it would deserve its own thread really.
Where I'm from they have some of the highest tides in the entire world and there's an area not far from here that has always been sort of a local talking candidate for such a huge project.
While 28 tonnes appears to be a lot of material for generating 1.2MW of energy, it compares favourably when you look at wind turbines. How often does this need maintenance though?
The positive thing about this design is that maintenance is potentially much easier than on an seafloor mounted turbine: if the tether is long enough, you can just make the craft surface next to a maintenance vessel with a small crane. No divers necessary, and no giant crane platforms like for offshore wind turbines, either.
I still worry about some of the technical aspects. The craft is going to pull it's own tether through the water behind/"under" it while it "flies" loops in the current at a speed faster than the current itself. That must induce quite a bit of drag, right? Especially because that tether is delivering several megawatts of electric power do the anchor, while holding all the mechanical load of that power being generated. That has to be a beefy cable. And the joints where that cable meets the craft and the anchor are moving parts, for all intents and purposes.
I also wonder how much the craft actually resembles a full submarine. Are there ballast tanks and ballast pumps for altitude control? Full set of diving and directional rudders? What happens when any of those fail?
Potential complexity is certainly higher than for an offshore wind turbine.
For those wondering how they transfer the generated energy from the tidal kite to the shore:
> The turbine shaft turns the [onboard] generator which outputs electricity to the grid via a power cable in the tether and a seabed umbilical to the shore.
I assume this does no harm to fish. And electricity can be easily transported back to land ( there was no mention of how this was done in the video ). Since it is portable, small, fits into a 40ft Container. And you could mass manufacture these, ship it with container. There isn't another manufacturing problem and transportation problem like wind turbine.
If Yes. You could have tens of thousands of these in north of Scotland of or seas around England.
I will 100% guarantee that the unique brand by Brit NIMBY-ism will rise, and some of my fellow citizens will complain about them affecting the nesting habits of the migrating lesser-spotted blue crested greeb warbler or something, and that'll be that. It's happened to many wind projects, this won't be any different (despite there being no evidence).
Never mind that if CO2 in the atmosphere continues to climb, all those birds will die anyway, the global food ecosystem will go crazy, hundreds of millions of people will die and so on: that picturesque estuary has to remain unencumbered with man-made engineering, or else!
> Surely there has to be a catch somewhere. Right?
Underwater things are expensive to maintain, nothing is 100% waterproof, so rust rust rust.
Underwater cables are no joke either, especially if you're building a network of sea cables. Making watertight is not cheap.
And there is the question of doing high power electricity under seawater. I'm not an engineer in that field, that I think it is going to being a whole lot of new headaches.
Underwater cables has been done as in all the Network connection across continents. The same with high power electricity under seawater.
None of these are new. However they are all 1 to 1 build up. These new tidal kite requires many to one. And I am not quite sure how this could be done. At least cheaply.
How on earth can such a small device generate so much energy? Wouldn't 1.2 MW of power make it very brittle just like a real kite? Or else why not scale it up and make one 100 times larger that generates 120 MW of power? Since tidal currents are much more reliable (I think) than offshore wind it almost seem to good to be true. There has to be a catch.
The speed of the tide between those islands is something like 5-6mph, and in some places much much higher (think tens of miles an hour).
Water is 800 times more dense, so moving water contains much much much more kinetic energy when its moving.
But that also means it has a lot more drag. That drag can be quadratic, meaning that you'd need to a monster fucking cable to stop it being dragged away by the tide.
The Grey Dogs channel between the Scottish islands of Lunga and Scarba has a peak flow of about 15km/h with large standing waves - quite incredible to watch this up close and watch the sea shooting past!
Definitely seems more feasible than a lot of crazy energy ideas! E.g. I think this makes more sense than the air versions because you don't have problems launching/landing or when the wind stops.
Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though. Also in most of the world (maybe not the Faroe Islands) this has to compete with solar & batteries which are getting cheaper and cheaper. If this is more than £5-10m then I think solar and batteries would be a much better option in most of the world.
> Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though.
Might, yes, but I think it’s unlikely all problems will be minor. Salt water isn’t kind to metal, no matter how well painted. Also, I expect barnacles will start growing on it. If you’re a filter feeder, this may be even better than sitting on the sea bed or on a whale.
Question will be how much that effects their $/MWh calculation. The only real way to find out is to try, I guess.
The good news is that we do have a bit of experience with metal machines that operate in sea water for decades. We (as in humanity, I don't) know exactly what to expect. You'd want to have a permanent service operation scaled exactly to how much overhauling capacity you need to put the tide kites in a round robin maintenance loop.
Have they? And how many of them can be ordered to surface under tide power, for easy maintenance access and towing into a maintenance dock without involving expensive divers?
I presume the tether on this would be built long enough for controlled surfacing, a longer tether means larger deadzone between inbound and outbound tide, but there won't be much energy in the flow close to the turning point anyways.
The huge difference between solar and tidal energy is the predictability. Tides can be predicted in advance - you always know exactly when and how much electricity you'll get. That's really valuable in a world of increasingly volatile electricity supply.
Solar will probably be far cheaper per installed MW (although capacity factor will be much lower), but batteries are still a long way from being cost effective. The cheapest batteries right now cost $100/kWh or $100k/MWh. Battery costs are still falling, but the curve is levelling off.
That price means that time-shifting 1 MWh of energy a day for 10 years would add $27 per MWh to the cost of electricity (ignoring ongoing maintenance costs, and assuming a 1MWh battery can do 4k cycles). The company behind this is forecasting $50/MWh of generation. Solar on its own right now sits at $30/MWh, although presumably that's for places with relatively high capacity factors.
The limitations are obvious - this is very geographically constrained. I suspect there will be a small place for this type of technology in the renewable mix - especially in remote and northern places. Then again, offshore wind is already sitting at below $50/MWh and doesn't have the same geographic constraints - so maybe it's a better bet.
I wonder to what extent its output correlates with that of wind energy in the same region. Having a reasonably independent set of generating technologies might help with the intermittent generation of sun-based renewables.
The steeper the slope the higher the power output.
I think the real question on tidal generation is how costly is maintenance. The sea is just a very unforgiving environment. Salt water and marine life fouling everything are difficult engineering problems that just add more expense than I can imagine wind turbines having.
If they can make tidal work I guess we'll end up in a world where most of their profit comes from keeping the grid alive when it's a calm and there's no sun.
I guess this may mean these technologies aren't going to really take off until we stop using hydrocarbons to make up the shortfalls...
I was hoping for some sort of diagram or animation about what this thing is set up and does underwater and how this movement gets converted to electricity. Does anybody know?
The turbine (propeller) at the back of the kite rotates and generates electricity.
Since this can 'fly' at an angle to the current, the speed of the 'kite' moving through the water, will be faster than the movement of the water - therefore the turbine can be spun faster than if it were just anchored in one spot.
The long-term projected levelized cost of the generated electricity really has to hit that $54/MWh target, otherwise the economics won't work - unless you absolutely must use some form of offshore energy production, then I guess it's an interesting niche application.
The tides are always moving so this energy is much more useful as baseload energy. They will lessen the need for energy storage for wind and solar, making wind and solar even cheaper.
So tidal doesn't actually have to be as cheap as wind and solar by itself, as it will lower the total cost of wind and solar and be economically viable as a part of the mix.
If you're a company operating wind or solar, then you will be able to have a much smaller battery installation, by using tidal kites for most of the baseload instead. And the kites actually generate energy instead of just storing it.
This system, as presented, will be really prone to *mechanical wear*. Maybe it can be done, but I need to see long-term (price & reliability) performance to believe it.
I can think of a propeller and generator, but those are solved problems. This is just a boat with a propeller. Only instead of using the generator as an engine to spin the propeller, the tides spin the propeller which generates power in the generator.
Steering is also a solved boat problem.
Then there's the tether and anchor. This is the reason it swims in a figure 8, instead of it just being a propellar anchored straight to the seabed. So the "pulling" force is actually mostly to the sides instead of directly on the tether and anchor.
I'm trying to see what prior art we can find on the internet on tethers and anchors used in fish farming and offshore oil industry, but I'm not finding many sources.
Interesting! Given the small amount of power relative to the total amount in the tides (I've seen an estimate of 3.7TW), this doesn't make a big difference to the Earth/Moon gravitational system, but I'm curious how this will affect the Moon's orbit (yes, I know it's millimeters or meters). For example, the Moon's orbit is increasing by stealing rotational energy from the Earth--i.e. Earth rotation slows down, Moon speeds up and orbital distance increases. Does this friction in the tidal system reduce the energy transfer to the Moon and therefore preserve Earth's rotational energy, or just redirect that rotational energy into our power grid? I would guess it would have to be the latter...
I believe it would reduce the transfer to the Moon. The Moon's orbit increases by stealing rotational energy from the Earth -- this happens because Earth's rotation carries its tidal bulge ahead of the Moon angularly, so the bulge pulls the Moon forward. The tidal harness uses some of the motion of the water to do work, so it gets carried less farther ahead by Earth's rotation, so it pulls the Moon forward less.
For comparison, electricity was sold to the U.S. grid at about $48/MWh in 2023. This is less than any of the cost projections mentioned in the article.
Howabout materials? It says this weighs 28 tons and makes 1.2 MW. That's 21g/W assuming a 100% capacity factor, no balance of plant, and assuming those are short tons. Compare to an iPhone 15, which consumes about 1W per 150g in use. That's a materials intensity multiple (EROI estimate) of ~ 7. An average automobile on an average commute dissipates about 67kW, or 27g/W for a multiple of ~ 1.
Perhaps surprisingly, it is a realistic cost and could be much lower if the electricity market were efficient (as opposed to being an amalgam of regional monopolies with essentially no price incentives).
When the wind isn't blowing, no wind generation. When the sun isn't shining, no solar. So these guys come in with a "gap" filling idea of using tidal, yet their own marketing says this "kite" parks itself when there is no tidal flow. So how is this continuous power generation?
It's not continuous, but would presumably be very predictable. And times of less movement would be different across the world which makes it possible to have some geographic resilience.
Fortunately they are smart. They will learn fast. This isn't a new problem. Ships do get whales caught in the propellers from time to time. I was in a ship that had exactly this experience in 2001. Whole ship stopped and wouldn't start again until the third attempt to start it. A crew member reported he saw blood and guts at the stern.
That has been attempted in the same location in Vestmanna in the Faroe Islands. From what I've been told it pulled itself loose immediately, and the anchoring was pretty significant. This kite swims in a figure 8, so I guess that doesn't pull as much on the anchor.
But this seems a lot easier to transport and install compared to cranes and the nightmare of navigating turbine blades on trucks through places. And if these hold up to water and don't cause too many problems for wildlife, there would be a lot less discussions about these "messing up my skyline", while tapping a new source of energy.
Quite interesting and cool.