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Submersible Glider Powered By Thermal Changes
An anonymous reader writes about a new robot submersible that uses temperature differences in the sea to power operation for more than twice as long as previous, battery-dependent vehicles. "The torpedo-shaped glider moves through the ocean by changing its buoyancy to dive and surface, unlike motorized, propeller-driven undersea vehicles. To power its propulsion, the submersible gathers thermal energy from the ocean. When it moves from cooler water to warmer areas, internal tubes of wax are heated up and expand, pushing out the gas in surrounding tanks and increasing its pressure. The compressed gas stores potential energy, like a squeezed spring, that can be used to power the vehicle. To rise, oil is pushed from inside the vehicle to external bladders, thus increasing the glider's volume without changing its mass, making it less dense. The oil can be shifted inside to increase the density and sink the vehicle."
Call me crazy, but I thought I remembered seeing something like this on the Discovery Channel (or somewhere on cable) a year or two ago... It's a pretty clever device, using the up and down motion to propel itself forward through the water for a reduced energy expenditure. Still, I'll bet they have a ways to go before these things can safely navigate the real hazards of long-term ocean research (I wish the article had working links to more info). Power consumption is a big part of that, but I'd imagine there's a lot of other stuff that can go wrong. The ocean is a pretty unforgiving environment for machines of any sort.
Irony: Agile development has too much intertia to be abandoned now.
That would be misinterpreted by the whales as an act of war...
You're crazy.
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Just sayin'...
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Submarines don't use changes in depth to push them horizontally. This device is a bit like a sailplane.
http://michaelsmith.id.au
and it works brilliantly. Mind, it's not a submersible so it's not quite so cool. it's just a device that opens the window in my greenhouse so that the tomatoes don't get too hot in the summer!
I know, I was shocked too, but the vaporware tag is wrong.
They have had one working that has traveled 1400 kms so far since launch in December. Better article here
http://www.cbc.ca/technology/story/2008/02/08/tech-glider-undersea.html
They've been testing it by cutting some cables, right?
It is spelled GLIDER. G L I D E R
On a more serious note gliding or "flying" under water as means of improving fuel efficiency and maneuvrability are not new. Research has been going on this since the 60-es. None of it has produced anything particularly spectacular.
Neat design, though there is a simpler way to do it. Put some solars on the glider, charge it on the surface, after that use the energy to compress the air used to expell the ballast tank. Sink. Reach target depth (gliding). Spew out ballast the same way a submarine does. Float up. Gliding. Sit on the surface while charging for another dive.
Trivial to do. No need for complex thermal stuff and you can probably survey half of the Pacific at a leasurely pace on one run until your batteries run out of charge cycles. This type of kit needs to float to the surface to transmit data back to base anyway, so why not do something productive in the meantime.
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and newer subs are not motorized, but nuclear-powered. Excuse me but what do you think a nuclear reactor and a turbine are? If they had 100 guys pulling a lever that moved the propeller, then you could say that they aren't motorized ( and you could argue that they have an human motor anyway...). But saying that a nuclear sub isn't motorized...
Scientists research, they discover, they do not invent. Engineers invent. Doesn't anybody in journalism know the difference between a scientist and an engineer? Also, the Prius is actually a bit like a conventional submarine - IC engine charges the batteries - and is therefore (from a marine engineering perspective) very old tech dating from before WW2. This on the other hand is seriously clever. In fact, it's like powering your car off a massive array of engine thermostats (which rely on wax as the operating means.) So a better lead in would be "Engineers have developed an energy efficient vehicle which is nothing whatever like a Prius - it uses temperature gradients in the sea to power itself."
Perhaps Microsoft deserves to take over Yahoo.
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Last I checked submarines had air tanks for buoyancy control, and newer subs are not motorized, but nuclear-powered. Something change in the past few hours while I was sleeping?
And those 'newer subs' use a nuclear reactor to power - guess what? - a motor.
There was a time when the average slashdot user had more than two braincells to rub together, but that time seems sadly past.
I'm old enough to remember when discussions on Slashdot were well informed.
Rather, gliders travel in virtue of the laws of reality alone. And at a speed of c/4.
Last I checked submarines had air tanks for buoyancy control
The air tanks are used mainly used to switch between surface and submerged modes, for trimming (keeping the sub horizontal), and to compensate for changes in water density. Because the amount of lift generated by a body does not change much with its depth, the air tanks cannot provide fine control of your diving depth. Also, a naval sub prefers not to use the air tanks once submerged, because venting air leaves a trail on the surface.
For fine depth control, a sub uses its diveplanes: wing-like surfaces that provide lift (positive or negative) as long as the sub keeps its speed above a minimum.
In effect, this glider reverses the process: changes in buoyancy are used to generate an upwards/downwards force, which is converted by the wings into forward motion.
newer subs are not motorized, but nuclear-powered.
You mean some newer subs are nuclear-powered. Conventional-powered submarines are still being built today. Often, in addition to the traditional diesel engines, an air-independent propulsion system is installed, either a Stirling engine or a set of fuel cells.
They never said that it had to carry people, and I bet it's a great research vessel since they have one working as a previous poster already said. Since it rides thermal currents in the ocean I think that you could put a GPS tracker in it and find some very good data about changing ocean currents, not to mention the vast amounts of other data you could gather with something like this that doesn't really need to refuel or resupply.
"Some books contain the machinery required to create and sustain universes."-Tycho
I assume you're getting at the same thing that I'm wondering... how much of an impact does this have on water temperature, currents, etc., if they're trying to call it "green"?
Of course, "green" doesn't mean much, but energy is never free, and taking it from an ecosystem is always going to have consequences.
In this case, we could try to use these, make them popular, and find out that they not only take heat energy from the oceans, but also change currents.
Likewise, we could try to cool the ice-caps somehow, but that wouldn't "counteract" what's happening with global warming; it would a more volatility to the system, with more extreme cold in one place battling more extreme heat elsewhere. The weather system is already too screwed up as it is without that.
And that's the REAL problem with this AND global warming: that we take things, on a massive scale, without any real respect for the damage it causes, or the slow processes that are needed to create what we take quickly. We can barely admit that we're doing damage, let alone facing the fact that the damage cannot be undone easily.
I'm not saying that we shouldn't use wind power, or solar power, or thermal power, or even combustion engines. BUT, we need to every bit of energy we take from the world -- in WHATEVER form -- depletes it, and that the only real solution is to cut back on how much we take.
Nice try though.
Absolute power corrupts absolutely. indymedia
True that!
But given this is a robotic submersible, why does it need air conditioners and lights?
No, the energy in that plan doesn't come from the sea temp, it comes from the ballast. The thing you're depleting is the available buoyancy material, whether it be helium, air, or oil.
For a closed-circuit buoyancy engine, you have to physically pump the buoyancy material around to get your change in density. This pumping is against whatever the ambient pressure is, so the deeper you allow it to drop, the more force you have to pump against to get your buoyancy back and return to the surface.
Since you have to pump the same volume of material either way, against a force that depends on the depth , it takes more work to get your buoyancy back the deeper you go. This works whether do the pumping on the bottom with oil-bladders, or at the top with air bladders.
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