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Underwater Ocean Kites To Harvest Tidal Energy
eldavojohn writes "A Swedish startup has acquired funding for beginning scale model trials of underwater kites, which would be secured to a turbine to harness tidal energy for power. The company reports that the kite device allows the attached turbine to harvest energy at 10 times the speed of the actual tidal current. With a 12-meter wingspan on the kite, the company says they could harvest 500 kilowatts while it's operational. This novel new design is one of many in which a startup or university hope to turn the ocean into a renewable energy source."
At first I read "Ocean Kitties" and wanted to see pictures of those...
Because of the tides, the Earth's rotational energy is being stolen by the moon, which is using that energy to slowly escape from orbit. (This is a diminishing effect over time, that will eventually reach equilibrium.) But when we leach this energy for our own purposes, we are changing the delicate balance of that equation. ...Siphon off too much energy from the tides, and we could either increase the rate at which the Earth is slowing, bring the moon crashing down upon us, or both!
Won't somebody think of the children? We owe future generations a planet fit to live on and capable of sustaining the future.
HSJ$$*&#^!#+++ATH0
NO CARRIER
now whales can enjoy the "renewable revolution" like migratory birds and bats do with windmills.
THL phish sticks
...supply of their starfighters to provide us with more of these kites.
-Will P.
Is it possible to exhaust the wind or sea's natural momentum, if there is such a thing? Where does the energy ultimately come from? In other words, is it theoretically possible to have so many wind farms (or, in this case, tide farms) that the atmosphere becomes still?
(captcha: "universe". heh.)
Seems this would be relatively high maintenance. Anyone who owns a boat knows that stuff can and will grow on it, which will have to be cleaned off eventually, no? Setting aside the initial cost, which isn't mentioned, wouldn't the maintenance be costly?
So has anyone considered what will happen when we massively start harvesting global tidal energy?
Will it affect global oceanic heat redistribution? (( If the ocean currents slow down then northern Europe reverts to looking like northern siberia. ))
What about the earth/moon relationship that drives the tides? Do we end up sucking more energy out of the moons orbital velocity leading to a decay in the moons orbit?
Environmentally, what happens to the organisms that live in the tidal zone?
Someone should have done the calculations before we started the petrochemical revolution. Where are we headed with the tidal energy thing?
If they're anything like my kites, they'll just end up nose-first in the silt.
Great minds think alike; fools seldom differ.
short answers: No, there is. The sun. No.
I suppose the whales might prefer it to the alternative:
http://news.bbc.co.uk/2/hi/americas/8664137.stm
last i checked power wasn't measured in meters/second.
very confused summary.
Like windmills, PV solar (and arguably, thermal solar), this will use a ton of capital (in multiple dimensions -- energetic, costs, and materials) to harvest very diffuse energy. The cries to subsidize installation -- and possibly operational -- costs will start almost immediately.
Dog is my co-pilot.
Tidal forces are from the moon, and over time the moon is getting farther away. Clearly, if we harvest tidal energy we will force the moon away faster as it makes up for the difference. If NASA times it just right, we could put people on the moon, launch the moon at Mars and have people walking on Mars just months later. Melt the polar icecaps on Mars, use tidal kites there, and repeat as needed to keep using the moon as our Earth/Mars space shuttle. Add Phobos and Deimos into the mix and space tourism can take off.
Next, we use the tide from the sun to travel to Alpha Centauri.
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We're talking tidal energy, so for the sea it's the moon (not the sun).
The numbers don't look very promising for this kind of device.
Let's assume you have a 12-meter by 5-meter "kite" and it's moving out with the tide.
And let's assume the tide is a huge one, like 10 meters.
Also let's be generous and assume the kite can sequester an average of one meter of depth of water.
That's 60 cubic meters of water, falling 10 meters, twice a day.
Jut for fun, switching back to English units, about 60 tons falling 63 feet per day.
or 120,000 pounds falling 63 feet per day. That's about 87 ft-lbs/sec, or about 110 watts. .33 cents an hour.
Wholesale electricity is going for about 3 cents a kilowatt-hour, so this kite is at best making
I don't think you can build deploy, and operate, and pay for a kite that size on that kind of income.
Just the interest lone has to be more than that.
Thanks to BP and Transocean its a Fossil Fuel source
GGP here - sorry, that sounds pretty stupid. The moon is orbiting the earth, i.e. doing nothing but falling. For that to be a source of energy, shouldn't the moon be coming closer and closer to the earth? Otherwise you're just creating energy out of nothing, by the mere fact of having celestial bodies close together.
The solution is obvious. I am selling gravity credits to absolve you of your moon-doom guilt. Each credit you purchase represents energy gathered from sources not directly linked to the moon's potential energy plus some of the profits will be used to fund missions that will increase the moon's potential energy. This gravity offset program will save the earth for our posterity. As the administrator of this program, I will, of course, take a percentage of the sales as compensation. My motives are, however, purely in the interest of the future.
One last thing: Sometimes I wonder; "Is that someone's signature? Or do they type that at the end of each post?"
Well ok. Anything wrong with that?
Well, if you can design a windmill, solar cell, tidal turbine or other naturally-powered generator so that you can leave it alone for decades (centuries?), it can pay itself off compared to the cost of operating a traditional fuel-burning plant, although the payoff time would be so slow it may need subsidies to get investment going.
I do agree that, beyond research/prototype funding, government shouldn't subsidize these technologies until they are able to compete commercially on their own merits. Until it's cost effective, the money is better spent on clean coal or nuclear.
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Rotation of the earth + gravity = tides.
Sig withheld to protect the innocent.
I was having difficulty visualizing this technology, from the text description. Here is a YouTube video that sheds more light. Spoiler: essentially the tethered kite does figure-8 patterns to continually move the turbine through the water.
http://www.youtube.com/watch?v=1qCDRj8TE9Y
Pretend I said something meaningful or insightful here.
The moon is orbiting the earth, i.e. doing nothing but falling. For that to be a source of energy, shouldn't the moon be coming closer and closer to the earth?
Actually what's happening is that the moon is getting farther away from the earth, gaining orbital velocity at the cost of earth's rotational velocity.
The source of energy is actually the earth's rotational energy, of which there is quite a bit.
The enemies of Democracy are
What units is that measured in? I'm not making sense of this sentence. Since when did the tidal current harvest energy in the first place?
So we have free energy until the moon crashes into the earth. I highly doubt that anything we are doing to suck that energy up is actually accelerating the process.
You haven't been paying attention to PV development lately, have you?
They've made quite a bit of progress lately. If you shop around your panels can be paid off in 10 years of less (PV lasts 30+ years). In energy costs its even less than that now.
And solar thermal pays off quicker than that and lasts even longer.
As for 'operational costs' you aren't familar with how windmills and panels work at all, are you?
Wind farms are unlikely to stop the wind. Wind is a byproduct of temperature differentials, and as such, as long as the earth isn't exactly the same temperature everywhere all the time, there will be wind.
Tidal farms, on the other hand, I don't know. Tides are due to the difference in gravitational fields at different points on the earth. As such, the tidal energy comes from the Sun's and the moon's gravitational field. Since neither the sun nor the moon are losing mass through the use of tide turbines, what has to change is the distance between the sun, moon and earth. Somehow, I think the time scales on which this becomes a problem are large enough that we'll have entirely different problems then.
The only real problem I can see with tidal turbines is that if they are large enough, they will restrict the flow of the tides, and tides will become less pronounced - which will have an immediate impact on any tidal areas. And since tidal areas and shallow bays are pretty much where the food chains for a lot of marine animals reside, this could be a real problem. But again, it would have to be something on the scale of putting turbines across the entire straight of Gibraltar, and reducing the flow to near zero. Unlikely to happen, but not impossible.
Those who can, do. Those who can't, sue.
Come on, it's better to just keep digging up and draining the ground until there's nothing left and hope for a bright future. That way when all the economically viable hydrocarbon sources are used up we'll have no backup plan and really be able to commit to sucking the teat of whatever corporations corner the next energy dependencies.
Is it possible to exhaust the wind or sea's natural momentum, if there is such a thing? Where does the energy ultimately come from? In other words, is it theoretically possible to have so many wind farms (or, in this case, tide farms) that the atmosphere becomes still?
(captcha: "universe". heh.)
I think we're OK for a while. There's many 'renewable' energy sources that can, and are, being tapped, and we're nowhere near extracting any significant fraction of them so far:
1. Tides, as in this article, come from the sun & moon interacting with the earth; http://en.wikipedia.org/wiki/Tides
2. Sunlight; there's plenty to spare: http://en.wikipedia.org/wiki/Solar_energy "Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used."
3. Let's not forget geothermal: http://en.wikipedia.org/wiki/Geothermal_power
Of course, that last one, being strictly a gift of today's Earth, could be compared to 'traditional' energy sources such as hydrocarbons (oil, gas, coal) and nuclear. We're nowhere near running out of those yet either.
"this will use a ton of capital (in multiple dimensions -- energetic, costs, and materials)"
Renewables are hardly unique in that. A single-reactor nuclear plant costs over 5 billion euros (see Olkiluoto 3) and takes half a decade to build.
If moon is doing the tide then how come there's high tide 2 times a month.
So actually sun contributes at least as much as the moon or a bit more. And the interference max of those is the high tide.
But earths rotation and continents actually make it meaningful.
If moon is doing the tide then how come there's high tide 2 times a month.
So actually sun contributes at least as much as the moon or a bit more.
No, the sun's effect is about half that of the moon. Though that's still significant.
But earths rotation and continents actually make it meaningful.
Earth's rotation is where the energy is actually coming from. It's why the earth is slowly losing rotational velocity to the tune of about ~15 microsecond longer day per year
The enemies of Democracy are
should be painfully obvious: where does that subsidy come from? Why, yes, from economic activity derived from burning fossil fuels.
We should be looking at truly sustainable energy solutions, not scams.
We will know an energy source is working properly when politicians seek to tax it.
Dog is my co-pilot.
I know I am a bit off topic here, but I am looking for some insight from someone who has a good understanding of physics to help me understand something.
There is obviously a LOT of energy being exerted by the moon and the sun in the form of gravity on the earth. All of these other solutions rely on harnessing this energy via a third source, such as harvesting the energy transmitted by the waves. Would it be possible to directly harness this gravitational and centripetal energy?
20th century Marxism is not progress...
Come on, it's better to just keep digging up and draining the ground until there's nothing left and hope for a bright future. That way when all the economically viable hydrocarbon sources are used up we'll have no backup plan and really be able to commit to sucking the teat of whatever corporations corner the next energy dependencies.
Well yes, you're exactly right, it _is_ better to do that. It always makes sense to keep using a cheaper product (as long as you accurately calculate all the costs) than a more expensive one. Some people argue we don't accurately account for the costs of fossil fuels (thus the interest in a carbon tax which is a way of doing so, albeit a tremendously inaccurate one guaranteed to be subject to massive political interference such that it most likely won't serve it's purported purpose in any useful way). But assuming the pricing is accurate, it's not like suddenly one day all the wells are going to run dry and there will be no oil. It will just gradually get harder and harder to extract (i.e. more expensive) and at some point it will make economic sense to evaluate alternatives. Indeed, this process has been going on since the day after the first oil well was drilled. Also, it's not like research into alternatives isn't going to be happening the whole time. Subsidizing economically unviable alternatives distorts this whole process in stupid ways (like germany having a huge installed solar base despite being a relatively inefficient place to actually do solar). In this sense, a carbon tax would be much better than subsidies - if you could actually create a level playing field where all technologies were priced properly, you'd wind up with the best one winning out. Unfortunately, that's a big if, and frankly it's never going to happen, because nobody will ever be able to accurately price these things even if you could keep the politicians from sticking their fingers into the pie and screwing things up. That's why I generally favour the status quo because _even with the unfair advantage fossil fuels have due to not fully accounting for environmental costs_, I think we are still better off than we would be with the massive inefficiencies that would invariably occur when trying to account for them in some artificial way controlled by a massive bureaucracy. And that's not even taking into account that wind and solar have some obvious effects that are not incorporated into the costing for them, and probably have still others that we haven't discovered yet but that will manifest if they are ever deployed on a large enough scale.
Yes, forcefully taking money from people is wrong. Charge enough for the energy to cover the costs, if ti's a feasible technology the energy companies will adopt it and it will pay for itself in time.
Yur gul-durned tidal power is throwin off me coal-fi'ed atomic clock! Ain't chou hippies ever tink 'bout keepin proper TIME!
I'm feeling hungry for some land fish.
He also mentioned the wind, which is ultimately an effect of the sun heating different sections of the Earth to different degrees.
If you are not allowed to question your government then the government has answered your question.
If moon is doing the tide then how come there's high tide 2 times a month.
I assume you meant two times per day? That's because the moon raises tidal bulges on both the near and far sides of the earth. Thus, as the earth turns, you pass under these bulges roughly twice per day. That's essentially the exact definition of a "tidal effect."
It's not like the moon pulls water away on the near side and does nothing on the far side. The tidal effect is caused by the differential of the moon's gravity across the earth's volume. This has a "squashing" effect.
Which means they will never be cost effective.
Clean coal does not exist, cannot exist and will not exist. It is just a marketing phrase.
This is not gonna work. Those kites would be right in the flight path of the rare spotted owl fish. Their mating habits will change and they might rub a dolphin the wrong way.
Not my fault. If you'd power your atomic clock with a renewable energy source, like hamsters or grad students, then you wouldn't have this problem!
The enemies of Democracy are
Belgium.
When you're afraid to download music illegally in your own home, then the terrorists have won!
How long would it take barnacles and other creates or plants to start to grow on this thing thereby increasing drag? I don't recall seeing anything growing on the blades of a windmill...
Has anyone thought of the job losses in the oil industry?
'Political power grows out of the barrel of a gun.' - Mao Tse-tung
Yes, while we're at it we should do away with those leafy trees, billions of acres of them, sucking all the energy out of the breeze. Might as well put an end to all the small furry animals too, and I never did trust birds, beady little eyes on them.
Seriously, the green hysteria machine has a lot to answer for.
What he can't kill, he has sex on. Trent.
at some point it will make economic sense to evaluate alternatives.
Well some people can see a little further then you and realize this stuff takes time to develop. It's good to have options BEFORE you desperately need them. And I wouldn't want this stuff made in a rush. That would just be bad planning.
Step one, lets confine these contraptions to a smaller segment so we don't collide with as many other living things, such as blue whales. That's also got to hurt the kite so it make s economic sense too providing you can steer wildlife around them. We will just have them fly closer together, but the tethers might tangle, so they must fly in organized formation. A figure 8 is out because they would just twist up their cables, so a circle it is.
Step two; To keep them from diving into the mud on the bottom during storms, and ruining their expensive little turbines, we can join them together on a central hub. Since they are on a central hub we can save weight by using one central generator, no individual cables to tangle, kill, or mame fish, and there will be fewer parts, therefore fewer turbine failures.
Ok, the final design looks like, well..., a big light weight propeller. And if so, how does "improving" on a brand new design bring me back to square one? What is so novel here, and what have they really solved? We have had tidal water turbines on the market for years and I have not seen a single one installed in my area yet. Economically they have just not been able to prove their worth without upsetting too many people about the damage they could do to the local environment. How does a kite solve those same problems and become "more economical" than an "improved design" of the same general technology?
Is that any different than the U.S. taxpayers subsidizing oil prices via their military engagements?
How does this scheme, and others, deal with the variety of underwater overlords that enjoy crudding up the works on underwater structures?
Please note I'm not Watercooler Guy, tossing out a cheap caltrop to maintain nerd herd level. I'm honestly curious. Most if not all of these schemes rely on precision surfaces exposed to seawater. Some of these projects will have been thought through beyond initial theory, so we must have some techniques and numbers by now. Where are we at with that technology?
For the punters, like me, who'll say "what about bottom paint?", bottom paint is bloody poisonous, as well as not perfect. So there we have the question of how long it's good for before the mechanism has to be raised and recoated, and what are the local & not-so-local effects that a field of poisoned structures will have on things like fishing and general eco-system.
So, where are we at with that particular problem of tidal power schemes? Somewhere on /. we're going to have a few people who've acutally looked into this, and hopefully they'll pipe up.
I wish I were as wise as ya'll so as to be able to decide which of these great technologies was going to be our best future decision.
The fact is, no one does know, and if they're really sure, they'll invest their own money (ie, buy shares in a company) into it instead of everyone else's (ie, clamoring for energy subsidies).
In general, subsidies have done very poorly at developing practical alternatives and very well at perpetuating inefficient systems that serve as a drag on their economy and real future progress. Compare corn ethanol to the massive boost in investment when oil hit $100 a gallon.
It's not as though we're going to wake up one morning and all the fossil fuels will be gone. There will be a (relatively) steady increase in price that will last decades. At some point along that, it will make sense for people to start investing heavily in finding more efficient alternative energy sources. Until then, these projects are mostly just a way to siphon off government funds on generally pointless endeavors. Not that I blame them - who *doesn't* want the government to pay people to use your product.
I can agree with that except for solar pv. If the economies of scale that take effect so strongly with lithographic processes can be caused by subsidizing solar pv to the point where it becomes competitive, then I'm more than willing to subsidize it. Of course, that's a big if.
Sure I'm paranoid, but am I paranoid enough?
It's only fair, since we so heavily subsidize the oil industry.
Or are you one of those people who believe that the cleanup and economic disruption in the Gulf will be eventually paid in full by BP? If so, I have some beachfront property in Prince William Sound I'd like to sell you.
"I guess the moral of the story is, don't paint your airship with rocket fuel." -- Addison Bain
But twice a month, the tides are extra high (and extra low). One of the extra high tides is higher than the other, this is when the sun and moon are on the same side of the earth. The not-quite-so-extra-high is when sun and moon are on opposite sides of the earth.
the tides are not caused by the gravity of the moon, exactly, but by the differential of the moons gravity on the near side of the earth vs. the far side of the earth.
THL phish sticks
I, for one, welcome our new Shipstone overlords.
http://www.heinleinsociety.org/concordance/S_HC.htm#shipstone "
When one pauses for a Coke, the deal is with Shipstone.
"
There is no right to feel safe thru security vaudeville at the expense of everyone's freedom, privacy and tax money.
That's the same system Sky Sails use (video). The kite makes, among other manoeuvres, figure 8 loops, and reaches speeds of up to 180 knots (180 nautical miles an hour, 207 mph, 333 kmph) in winds of 3 to 8 Beaufort (10 to 40 knots). It's actually a very similar design, that's also doing its part in reducing fossil fuel consumption.
I hope they manage to balance construction and maintenance costs with profits. It sounds promising, but then so do a lot of things.
I'd rather you rationally disagree than irrationally agree.
Well it still requires people with their own money to invest in this stuff. Because we're talking about subsidies. Now, if the government built it entirely, then the government would own it. But they're only encouraging investment in a general direction. A cleaner, safer, more sustainable future.
And ethanol is a fantastic alternative to farm subsidies.
Great locally, but not a silver bullet. Just not enough energy to harvest globally (same problem with wind power).
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1. A windmill this isn't. (And it's no regular watermill, either.) Comparing gliding surfaces to windmills might seem intuitive at first, but when you consider how most of the experimental kite systems for both land and sea actually operate, it's usually an apples-oranges comparison.
2. So far, very similar land-based systems for using kites in the air to generate power have proven themselves viable and immediately useful, and are approaching commercialization. They can get at winds in higher altitudes without a tower (just cables instead) and can also be flown in tandem on the same line to increase the power generated at a single installation, something that windmills can't easily do. Oceanic systems will almost certainly enjoy the same reduced overall cost (we're talking extremely typical hardware for these things - the only exotic component of the whole system is the automatic controls) and scalability of their land-based cousins. (Again, both windmills and tidal dams scale very poorly. Tethered gliders don't, as any kite train will prove.)
3. Since the amount of infrastructure required to support these things physically is so much lower than a tidal dam (or a windmill tower) it can be assumed that the return on investment is going to be higher, both in terms of money and energy. This particular design should also be highly portable, but a lot of that depends on how it connects to the power grid on shore.
4. Siting is everything, but nearly everywhere in the world ocean currents are most definitely not diffuse. (Something which also applies to winds at higher levels, especially in places near the jet stream.) There are three options for dense renewable power, and we only exploit one of them on a routine basis. One is hydroelectric power from rivers and waterfalls. Another is high-altitude wind, which land-based kites are already beginning to tap. The third is the ocean current, of which tides are a part, and is accessible using nearly identical technology to high altitude wind power. (HAWP) There's no reason to yet assume that ocean current power is just another 'secondary' power source, though healthy skepticism is always warranted on a case to case basis.
This isn't the method I would have chosen, personally. Using a boom or a winch works great on land for flying kite-based systems as opposed to 'turbine aloft' designs, with this system being more like a 'turbine adrift'. But I digress. This kind of dismissal is unwarranted and completely premature, especially when comparable technologies are shaping up very nicely. Likewise, it's too early for me to slap my seal of approval on it, but I believe the chances of success and competitive primary power generation here are a great deal higher than you think. With all due respect I'm confident that your assumptions that this won't be an economical power source will be proven very wrong, and look forward to that.
A follow-up question- would it be possible to build so many solar panels that all the energy from the sun gets sucked up and the planet freezes over?
Harvesting energy from the tides will sap additional orbital energy from the Moon, causing it to spiral off into deep space. SAVE THE MOON!
What do you mean geothermal could be compared to hydrocarbons? Isn't geothermal powered by the heat difference between terra and subterra? Is that heat entropy really exhaustible?
I hate it when people just give off statements, and expect us to blindly believe them without any arguments connecting it to a common set of paradigms.
This is not about you being right or wrong. (I think you are right.)
It is about the arrogance.
Reminds my of the typical physician’s got complex.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
The answer is: Yes. Obviously.
Put a roof above everything on the whole planet, essentially encapsulating it in a shell of solar panels, and the planet will freeze over.
The same thing is true for wind. A wind turbine takes kinetic energy from the moving air, and transforms it into electrical energy. Hence the air loses kinetic energy. Hence it slows down. Because of the law of energy conservation. QED.
See, when you want to act smart, you have to check that what you want to present as a silly question, isn’t actually a valid one.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
I'm glad you took my question at face value, instead of seeing the point I was making. Yes, technically if someone were to cover the entirety of the planet's surface with solar panels (of course ignoring the fact that there's nowhere near enough resources, manpower, or time in a person's life to actually accomplish such a feat) then most of the sun's energy would not reach the surface (I'm sure a little of the warmth the panels soaked up would reach the surface via heat transfer) but no country, or even every country combined together, could actually pull that off.
Likewise, the amount of wind turbines required to sap all the wind energy from the atmosphere would be staggering, and you couldn't just put them on the surface, you'd have to stack them so they reached the higher levels- the atmosphere's moving around up there, too- and you'd have to pack them densely enough that no air could get past any blades.
I would hope you don't actually consider either of these things to be even remotely feasible, even if they are theoretically possible.
See, saying QED after a post really just doesn't make you sound any smarter at all. It tends to have quite the reverse effect.
I love the slanted quote from the article:
"One of the big advantages of their technology, Minesto executives say, is its small size -- 12 meters for the wingspan and one meter for the turbine -- relative to other tidal-energy designs"
They neglect the 100' tether and the area inscribed by the kite.
They also neglect to mention that at slack tide the kite must be reeled in and re-launched as there will be no movement to keep the kite off the bottom. This is much more complex that a kite staked to the bottom of the ocean.
On the positive side, I bet the kites would work well in strong ocean currents like the Gulf Stream.
Finally a question;what is the minimum tidal speed that would be required to "fly" these kites and how that compares with tidal speeds around the world?
Movak
Different energy sources make sense for different reasons. Windmills for instance have a very small unit size, but that also means that if one is down for maintainance there is little difference to the total energy generated. Distribution and peaks also drive the use of technologies other than pure base load ideas. Some technologies are actually complementary in ways I doubt you have considered, for instance solar thermal providing preheating at a coal thermal power station (Liddell NSW, Australia). I can also see a strong argument for wind driven pump storage to supply water for hydro at peak loads.
Then there is the obvious niche filled since the 1970s of small installations off the grid where PV solar etc is competing against internal combustion engines. Then there's things like google's solar in datacentres - effectively just a giant UPS which makes perfect sense if California's electrity supply is as poor as it used to be.
It isn't arrogance. Its just that sometimes I don't feel like explaining myself. Sometimes I am pressed for time, sometimes I am lazy, sometimes it won't do any good, sometimes it is part of my sense of humor and sometimes I feel that brevity is a virtue.
Tangentially related:
I hate it when people ask me to provide sources when common knowledge and some googling will do. Hell, half the time my sources are not from the internet and I would have to google just to find a different but related to provide.
Like windmills, PV solar (and arguably, thermal solar), this will use a ton of capital (in multiple dimensions -- energetic, costs, and materials) to harvest very diffuse energy.
Kites use two orders of magnitude less material than a turbine of equivalent swept area. Water is two orders of magnitude denser than air.
This is starting to add up to something that doesn't sound so diffuse any more.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
I was getting at the newer coal processes, which generally fall under clean coal. I'm in Terre Haute, and nearby there is a plant using a similar (if not same) process, which is high efficiency compared to conventional coal plants (therefore cleaner), and they can separate the sulfur as a liquid, which is much cheaper and more effective than typical scrubber setups (hence cleaner), in addition to sorting out a lot of the heavy metal pollutants (I don't know the specifics). I know there is no such thing as coal being as clean as wind, and I never meant that; the hyperbole is marketing hype, but clean coal simply means clean relative to normal coal plants. Coal is cheap and plentiful, so we will continue using it no matter how much people complain about it as they want expensive wind and solar without paying more for it. By investing in clean coal, we can at least reduce how much we pollute with the coal we are using. I'm all for eliminating coal, but only when it is realistic to do so.
As for the other technology becoming cost effective, yes it should- I am not proposing we stop research, simply we stop subsidizing wind farms beyond prototype runs. We over-invested in ethanol before it became cost effective, and now it's a complete disaster. If we waited until the (yet to come) efficient cellulosic ethanol before investing, it would have saved a lot of headaches. Wind is developed enough it doesn't need subsidy in ideal locations. The technology is still developing to make it effective to build large wind farms in the Great Plains, yet Indiana is already getting one of the largest US wind farms put up. If we waited 10 years I bet the windfarm could be built without subsidy.
Keep in mind money is finite (congress doesn't know this yet), so money spent on subsidies means money not going to research to better improve the technology. The subsidized windfarms help get manufacturing more efficient, but most of that money goes to businessmen and investors, not scientists and engineers.
I'm sure subsidies can be cost effective if used properly, but the way they are right now I feel research gets a much higher ROI.
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The tides are "not-quite-so-extra-high" when the sun and the moon are at 90 degrees to one another (relative to earth). When they are at opposite sides of the earth, you also have high tide, because the sun amplifies the moon's "squashing" effect (as described by pclminion at the post above). see: http://en.wikipedia.org/wiki/Tide#Range_variation:_springs_and_neaps
Whenever in an argument, remember this.
assume we pull energy out of it.. the moon will come closer to earth (or reduce it's movement away) - so the total energy supply would be the potential energy of the moon in relation to earths gravity well.
Quite the opposite! The moon will move farther away, faster.
You state this yourself. The earth is slowing down and the moon to move farther away.
Harnessing tidal energy does obviously not reverse the process - it speeds it up. The kites are an additional brake on tidal waves, which will (very slightly) increase the torque on the moon.
The energy source is the earth's rotation.
I lost my sig.
it's all fun and games until you catch THE KRAKEN !!!
so if a wave smashes into a shore ...errr...
the impulse travels thru the continent and
exits the other side to become a wave again?
-
oh, that's why beaches are hot. the kinetic energy
of the wave is turned into heat.
Judging from the actual amount of power you can find in waves, we'd need to build a bloody shitload of these turbines to have any effect at all, really.
Besides, there's places on the planet where reducing the energy in incoming waves might actually be a good thing.
People replying to my sig annoy me. That's why I change it all the time.
Interesting world you live in. However in mine sometimes things go wrong without some sinister figure stroking a white cat organising them, although I'll have to admit the utterly stupid and sometimes outright criminal way the Californian power system was run in the 1980-90s could easily inspire such paranoia - but I could just look at that from a distance and laugh.
:)
The main point is not too many eggs in one basket.
Another good point to consider is wide distribution of power sources or a robust power transmission network. Once when there were major blackouts in my area a power station less than 1000km away was not running at full capacity but the transmission line was close to being red hot and couldn't take any more current. Firing up an idle unit wouldn't have done anything in that case. That incident did inspire construction of another major transmission line linking the two areas.
Bah - kids today! I had to make do with a Z80 asm instructor
It really IS all about the motion of the ocean?