TROPICAL CYCLONE: Could simple man-made structures in the ocean stop tropical cyclones, such as Typhoon Lupit pictured here?
Image: NASA MODIS Rapid Response Team
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Tropical cyclones, or hurricanes as they are known in the regions bordering the Atlantic Ocean, are among nature's fiercest manifestations, capable of releasing as much energy as 10,000 nuclear bombs. Hurricane Katrina leveled New Orleans and the Mississippi Gulf Coast leaving more than 1,800 people dead; Typhoon Morakot killed more people and did more damage to Taiwan than any other storm there in recorded history; and Cyclone Nargis devastated Myanmar (Burma) and resulted in at least 146,000 fatalities.
Could the formation of these storm systems be tempered or even arrested by technical means?
This past June, a plan to reduce the severity and frequency of hurricanes leaked to the public in the form of a patent application under Bill Gates's name (along with many others), resuscitating speculation about a scheme that has been proposed off and on since the 1960s. The core of the idea remains the same: mixing the warm surface waters that fuel tropical cyclones with cooler waters below to drain storms of their energy. But now Stephen Salter an emeritus professor of engineering design at the University of Edinburgh proposes a new—and possibly more realistic—method of mixing.
Salter has outlined in an engineering paper the design for a floating structure 100 meters in diameter—basically a circular raft of lashed-together used tires (to reduce cost). It would support a thin plastic tube 100 meters in diameter and 200 meters in length. When deployed in the open ocean, the tube would hang vertically, descending through the warm, well-mixed upper reaches of the ocean and terminating in a deeper part of the water column known as the thermocline, where water temperatures drop precipitously. The point of this design is to transfer warm surface water into the deeper, cooler reaches of the ocean, mixing the two together and, hopefully, cooling the sea surface. Salter's design is relatively simple, using a minimum of material in order to make the construction of each of his devices cheap (millions of used tires are thrown away each year, worldwide); his scheme would also require the deployment of hundreds of these devices.
Using horizontal wave action at the ocean surface, passive no-return valves would capture energy by closing after a wave has passed through them, allowing the circular interior of each device to raise the level of the seawater within the device by, on average, 20 centimeters. The weight of the gathered warm water would thereby create downward pressure, pushing it down the tube.
The idea is that hundreds of these floating wave-powered seawater pumps would be deployed year-round in areas, such as the eastern tropical Atlantic and the Gulf of Mexico, where hurricanes typically spawn or grow in intensity. (The devices would not, as widely speculated, be deployed only in the path of a hurricane that already formed.)
Salter says he was inspired to invent his device after seeing the damage wrought by Katrina. "I was called to a meeting at [intellectual property firm] Intellectual Ventures where they wanted to talk abut hurricanes, and they were very enthusiastic about it," he says.
The pumps have been named the Salter Sink by the firm, which patented them. Bill Gates was in the session at which Salter proposed the pumps, according to Intellectual Ventures CEO Nathan Myhrvold, and it is the company's policy to list as authors everyone present at a brainstorming session on the patents that are filed as a result of it.
Biological productivity could be side benefit
By mixing warm sea-surface water with the colder water beneath year-round, Salter thinks these pumps could keep the surface temperature below the 26.5 degrees Celsius threshold, beyond which the frequency and severity of hurricanes increase markedly. Salter and some of his co-authors on the original patent think the pump might even increase the biological productivity of the seas in which it's deployed, because it would mix nutrient-rich, deep water with warm, relatively nutrient-poor surface water. Nutrients from deeper parts of the ocean would be brought to within 100 meters of the surface, the deepest that sunlight can penetrate and power the photosynthetic plankton that are the base of the ocean food chain. This would be a boon to fish populations in the ecologically unproductive "biological deserts" of tropical seas where hurricanes spawn and the devices would be deployed. In these areas, little mixing occurs and populations of plankton—and therefore fish—are limited by available nutrients.
Ricardo Letelier, a microbial oceanographer at Oregon State University, however, points out that the effects of increasing available nutrients in the ocean can be unpredictable. "If you were to keep the pumps running continuously…you may allow phytoplankton to bloom," he says. "If you do it for too long, you get a successional pattern where grazers take over and recycle nutrients. And that's one of the problems we've had with iron fertilization experiments—the response of biological systems are not linear."
And Letelier warns that deep ocean waters contain a great deal more dissolved CO2 than surface waters do, because expiring plankton sink in the water column, almost like the rotting leaves on a forest floor. In addition, the solubility of CO2 in water increases with depth and decreasing temperature. As a result, mixing the two layers of the ocean would inevitably lead to significant transfer of CO2 from the biggest carbon sink on Earth—the ocean—to the atmosphere. The process is similar to what happens when you open a carbonated beverage—the drop in pressure causes dissolved CO2 to come out of solution and enter the air.
Is the thermal effect sufficient to abort fledgling storms?
Even if the pump were to succeed, bringing surface water to the depths of the ocean would have little effect on sea-surface temperatures, says Bill Smyth, a physical oceanographer and member of the Ocean Mixing Group at Oregon State University's College of Oceanic and Atmospheric Sciences. That's because the first 20 to 100 meters of the ocean above the thermocline are already so well mixed.
"If you take 20 gigawatts of heat away from surface, you think that has to cool it, but that is not necessarily true," Smyth says. "What it's actually going to do is raise the base of the mixed layer. If the base is at 50 meters, and you pump away the upper meter of the ocean, the mixed layer will then extend down to 49 meters. It's not that the 20 gigawatts disappear into thin air. It's just that it's not doing anything useful in terms of changing sea-surface temperature."
Salter counters that many of the areas where his pumps would be deployed, such as the Caribbean, have thermoclines that start at depths as shallow as 10 to 15 meters below the surface, thereby requiring significantly less pumping in order to strip the warm water from the top layer.
"It would just mean you'd need to pump for longer, but then [the] effect would last a lot longer," Salter says.
Are ocean thermal systems just too big for this technique?
Letelier thinks that, based on Salter's current plan, the scale of any deployment that would have sufficient effect on ocean temperatures to alter hurricanes would be impractically large. And he may know whereof he speaks, because he collaborated on a different ocean-pumping scheme involving long, meter-wide plastic tubes designed to suck water from the depths. That project failed after only 48 hours in 2006 in Hawaii but nonetheless is still being pursued by a company called Atmocean.
"I wouldn't be surprised if in the work of Salter you'd need at least one of these pumps per square kilometer just to make a dent," Letelier says. "That is a huge endeavor. You cannot do it, basically."
But Salter estimates that the mean annual transfer rate of a Salter Sink from the ocean surface to the depths would be 150 cubic meters of seawater per second, or 9.5 gigawatts of power—the equivalent of 10 large nuclear or coal-fired power plants (although this thermal energy has proved difficult to harvest). So, at this rate he calculates that for hurricane alteration his plan would require hundreds of sinks, and not the millions that have been proposed in other oceanic pumping schemes, including one in which Letelier was involved.
Then, there are the shearing currents
Another concern is shearing currents. Jonathan Nash, an oceanographer at Oregon State who is also part of the Ocean Mixing Group, points out that at the interface of the ocean's warm surface water and the cooler water beneath a wide array of competing and reinforcing undersea streams cause powerful shearing currents in which different layers of the ocean move opposite one another at speeds ranging from 20 to 50 centimeters per second.
"Those currents will take this tube and push it sideways. It will get flattened where the shear layer exists," Nash says.
Salter avers that it would be possible to create a downward tube constructed of stiffer materials, but even an extremely strong structure might not be enough, Letelier says.
"In the open ocean the amount of shear that goes on in the upper 50 meters of the water column—the mixed layer—they are incredible forces," Letelier says. "A 100-meter diameter and 100-meter-deep system in the ocean is a big wall against those currents."
The next step: Money
Despite their concerns about the plan, both Smyth and Letelier think it is worth doing more work to address the issues in the existing proposal. Unfortunately, funds to actually build one of Salter's devices have yet to materialize. "We are doing early prototypes to test the idea but our business model is invention," says Intellectual Ventures spokesperson Shelby Barnes. "We are simply not funded to do the next level of in-depth research needed, but our inventors would be interested in collaborating if there were additional resources."
To wit, Intellectual Ventures does not actually build any of the ideas it patents, despite the substantial fortunes of Myhrvold and others who are involved, which means a willing licensee would have to take on the project.
One use of future versions of the Salter Sink could be experiments that examine the responsiveness of the microbial communities of the ocean to mixing. If the Salter Sink were to be evolved into a practical geoengineering scheme, preliminary experiments of this kind would be absolutely necessary, Letelier says.
"There are some pretty big holes in the thinking that need to be patched up," Smyth says. "In science we try not to say anything's impossible or step on anybody's bright idea, but stripping away the entire wind–mix layer of the ocean—that is a huge task."
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23 Comments
Add CommentWhat hubris, to think nature can be controlled by humans. They can certainly do damage, in ways they can't predict (damage from the human perspective). I'm glad some are raising concerns about the side-effects of such a plan. There is a tendency for some people to assume that only good can come of their plans. In nature, you don't do just one thing, every action has unforeseen impacts. When will we learn that?
Reply | Report Abuse | Link to thisThe whole premise is wrong. The assumption that we don't need cyclones so lets find a way to stop them. I don't believe they exist just to cause humans problems they are probably essential to our survival. What arrogance..
Reply | Report Abuse | Link to thisFeel free to direct readers to the Intellectual Ventures Laboratory blog site, where more information can be found on the Stratoshield and the Salter Sink:
Reply | Report Abuse | Link to thishttp://intellectualventureslab.com
the plan is not to get rid of them altogether but to reduce the strength of them and thus reduce damages both financially and to the people in the path.
Reply | Report Abuse | Link to thisHurricane Katrina did NOT level New Orleans. In fact, New Orleans wasn't leveled at all. It was flooded. Flooded by the incompetence of the United States Army Corps of Engineers, which built poorly designed and shoddily constructed levees and floodwalls. This is was the conclusion of a National Science Foundation study in 2006 headed by UC Berkeley Professor Bob Bea.
Reply | Report Abuse | Link to thishttp://www.ce.berkeley.edu/projects/neworleans/
Nature has a self-controlled mechanism to diminish hurricane strenght: in the years where sea temperatures and solar cycle are in their top, favoring more abundant and stronger hurricanes, a tendency exists for dust storms from Sahara desert to reach and cool the sea by reducing insolation in the region where huricanes start
Reply | Report Abuse | Link to thisThe reconstruction of New Orleans was a "machada", hope it will take a very long time till the next superhurricane
Reply | Report Abuse | Link to thisSo am i getting it right thinking Bill Gates is trying to pre-empt this guys idea? Same old Bill! I think it's a crock though...all you would do is create hazards to shipping although some fauna might benefit like they do on oil derricks. Hurricanes will happen, people just need to build smarter near shorelines. .......and what is a 'machada'? A herd of he-goats? That might fit actually lol.
Reply | Report Abuse | Link to thisI think we should approach this cautiously. Like in forest fires, there is extra energy in the weather system, that needs to be dissipated. If we dont allow that, this may create a bigger problem down the line. We should be very mindful of doing these changes. In case of forest fires, if we dont allow the forest fires, it inevitably leads to much bigger forest fire later. I am not sure whether this is the right analogy.
Reply | Report Abuse | Link to thisTHE WAVE-POWERED PUMP
Reply | Report Abuse | Link to thisA longer version of this was posted by me in 2004.
For more on this and other ideas, see my blog at isecke.blogspot.com
There is a description of use to control hurricanes along with several other applications
On reading a book called Waves and Beaches by Willard Bascom (Anchor Books, 1980), I found a description of what I thought was a very clever device. It was a wave powered pump invented by John Isaacs, a simple and versatile device. Since that time I have often thought about applications for it. The pump consists of a float connected to a long pipe which hangs below it in the water. The pipe is fitted with a check valve that permits water to flow in only one direction. As the float and pipe move up and down with the waves, the water column in the pipe is forced to move along with the pipe when the pipe is moving in the direction that forces the valve in the pipe to close and, due to the momentum of the moving water, it continues to move in that direction even when the motion of the pipe reverses and the valve opens. This action results in a continuous flow of water through the pipe. The flow rate of the water through the pipe is proportional to the cross sectional area of the inside of the pipe and to the maximum speed of the up-down motion of the pipe. For a given size float, it can pump a lot of water at low pressure or a little water at high pressure. A short fat pipe will pump a lot of water at low pressure and a long thin pipe will pump a little water at high pressure. The pressure due to the flow of the water in the pipe is proportional to the length of the pipe. The components of the pump are simple and inexpensive.
Bill Isecke
541 Queen Anne Road
Teaneck NJ 07666
201 836 8403
bisecke AT gmail.com
Controlling the weather is a step in the right direction, go Bill :)
Reply | Report Abuse | Link to thisThis is just another completely impractical geoengineering idea, that's all.
Reply | Report Abuse | Link to thisThere are better ways against hurricanes like constructing steel and/or concrete reinforced buildings or or making building foundations higher than ground level in flooding regions, and/or improving the general shape of buildings to better stand against strong winds and so on.
Has anyone thought about the possible CO2 emissions that would be released through the increased biological respiration that would happen at the now nutrient rich surface levels? If the primary production (photosynthetic bacteria and algae) did increase due to the limiting factor (low nutrients) being eliminated or decreased, then this would cause an increase in the organisms that feed on the primary producers. These predators would respire.
Reply | Report Abuse | Link to thisThis brings to mind an experiment done in 2004 by P. Boyd about trying to sequester CO2 in the ocean's by providing the micro-organisms with enough of a limiting to grow (thus storing carbon in their bodies) and sink to the bottom when they die. What they found however was that the situation played out as described above, with the predators respiring more CO2 than the primary producers effectively absorbed.
So I guess the point I am trying to get at here is: have the effects to the ecosystem fully been thought out for this proposal yet?
Yes mahaperu I agree. You know what, if they go ahead and do this, the whole upper layer of the ocean from from the surface down to 250 meters would get warm as warm water stays over cooler water and will remain near the surface. THE PUMPS WILL ONLY HELP THE SUN TO WARM A DEEPER LAYER OF THE OCEAN SURFACE WATERS!!! When this happens, the pumps will eventually start pumping up warm water as they would have essentially trapped the warm water below the surface preventing its heat from gradually dissipating at the surface throughout the year and actually worsening the problem they are trying to solve. This would actually warm the sea surface waters to a greater depth even though at first the surface would be cooled. With deep warmer water a few years down the line, we would probably get more hurricanes and more powerful ones, after a few years of weak hurricanes. These scientists are too short sighted.
Reply | Report Abuse | Link to thisYes mahaperu I agree. You know what, if they go ahead and do this, the whole upper layer of the ocean from from the surface down to 250 meters would get warm as warm water stays over cooler water and will remain near the surface. THE PUMPS WILL ONLY HELP THE SUN TO WARM A DEEPER LAYER OF THE OCEAN SURFACE WATERS!!! When this happens, the pumps will eventually start pumping up warm water as they would have essentially trapped the warm water below the surface preventing its heat from gradually dissipating at the surface throughout the year and actually worsening the problem they are trying to solve. This would actually warm the sea surface waters to a greater depth even though at first the surface would be cooled. With deep warmer water a few years down the line, we would probably get more hurricanes and more powerful ones, after a few years of weak hurricanes. These scientists are too short sighted.
Reply | Report Abuse | Link to thisThe point that no-one that I have seen has raised is that the waters that get heated in these areas contribute towards the gulf stream that flows up towards the UK. This keeps contries like the UK warm as they are on the same latitude as siberia and canada. If you shut the gulf stream down you shot down North Est Europe and kill all the attached animals, sea life and vegitation that rely upon the temperate climate from the gulf stream. So Mr Gates is obviously prepared to freeze UK and northwest Europe just so that an area in the US that is built below sea level will be protected. A friend from Porto Rico said to me that they do not have many problems with Hurricanes in Proto Rico because their houses are build to withstand hurricanes than having the disposable attitude for construction that they have in some areas of the US and the Gulf. Just plan for the worst, since hurricanes happen every year. I would press Mr Gates to not invest in things that could shut down the gulf stream .
Reply | Report Abuse | Link to thisWhat would be the effect of a "Salter Sink" on the Gulf Stream circulation?
Reply | Report Abuse | Link to thisI think the idea is not a good on for several reasons.The process they are describing is already done by the cyclone itself. As a cyclone moves along a warm oceanic surface, it causes turbulent mixing in the oceanic mixed layer. This shear cools the oceanic mixed layer as cool water is entrained from the lower layers. This is treated as a negative feedback when considering the intensification of a cyclone. But if the warm water is deep (usually determined by the depth of 26 C isotherm), the oceanic heat content may be large (Leppier, 1972) and the cooling of the mixed layer is inhibited leading to the intensification of cyclone. Thus as we can see, the intensification of a cyclone is not a function of Sea Surface temperature but the total upper layer of the ocean through which it passes ( this energy is called as Tropical cyclone heat potential ). So if Salter Sink is deployed in the ocean, we are unable to cool the total upper layer.
Reply | Report Abuse | Link to thisSuppose if we pump the warm water to deep ocean and allow the cold water to entrain, are we sure that it will remain cold? No. Due to the heat from sun, this layer will also warm up leading to more warmer upper layer. Thus it will make the Cyclone more intense than actually it would be. Thus with Salter Sink we are not going to kill the cyclone, but further intensify it. I consider this issue as a serious one than the other factors.
I think the idea is not a good on for several reasons.The process they are describing is already done by the cyclone itself. As a cyclone moves along a warm oceanic surface, it causes turbulent mixing in the oceanic mixed layer. This shear cools the oceanic mixed layer as cool water is entrained from the lower layers. This is treated as a negative feedback when considering the intensification of a cyclone. But if the warm water is deep (usually determined by the depth of 26 C isotherm), the oceanic heat content may be large (Leppier, 1972) and the cooling of the mixed layer is inhibited leading to the intensification of cyclone. Thus as we can see, the intensification of a cyclone is not a function of Sea Surface temperature but the total upper layer of the ocean through which it passes ( this energy is called as Tropical cyclone heat potential ). So if Salter Sink is deployed in the ocean, we are unable to cool the total upper layer.
Reply | Report Abuse | Link to thisSuppose if we pump the warm water to deep ocean and allow the cold water to entrain, are we sure that it will remain cold? No. Due to the heat from sun, this layer will also warm up leading to more warmer upper layer. Thus it will make the Cyclone more intense than actually it would be. Thus with Salter Sink we are not going to kill the cyclone, but further intensify it. I consider this issue as a serious one than the other factors.
Cyclones are a cooling mechanism that pumps heat into the upper atmosphere above most of the CO2 to where it can be radiated.to space. "Heat elevators" Joanne Simpson: http://earthobservatory.nasa.gov/Features/Simpson/simpson4.php
Reply | Report Abuse | Link to thisshows that temperatures at 59k feet can be 10-18C warmer than the surrounding air.
Machada - heroic deed, macho bravado. (not sure why the word is feminine, though.)
Reply | Report Abuse | Link to thisAlways look forward to nature's response to our meddling. (This would be tongue-in-cheek, but I've bit my tongue off trying not to scream at humanity's hubris.)
Reply | Report Abuse | Link to thisTwo things spring to mind:
Reply | Report Abuse | Link to this1. A structure this large could present a hazard to navigation for shipping. How could this be avoided completely or minimized?
2. Since Bill Gates is listed (however serendipitously) on the patent application, and since The Bill and Melinda Gates Foundation makes grants in the near-zillions of dollars, why not apply to them for a bit of seed money? Nothing ventured, nothing gained.