One of the consequences of global warming is that more energy is available in the ocean and the atmosphere to produce weather. Energy from the sun heats up the surface of the ocean. As that heat irradiates up and fuels storms, they can become ever more dangerous hurricanes. Reducing their destructive potential is possible if we could cool off the surface of the ocean.

A few years ago, Intellectual Ventures inventors, including wave energy expert Stephen H. Salter, an emeritus professor at the University of Edinburgh, began work on a new approach that may offer a more feasible and affordable way to drain energy from hurricanes and typhoons.

As we head into this tough hurricane season, we wanted to answer some of the most common questions we receive about the Salter Sink.

How does it work?
The system would work by cooling the sea surface in one or more key regions of “hurricane alley,” the warm corridor in the Atlantic Ocean through which the most damaging storms typically pass. (A similar corridor exists in the western Pacific Ocean, and the same principles apply there.) The system need not cool the upper ocean by much to succeed. A drop in the temperature of the warm layer by as little as 1–2 °C would be expected to drain significant power from an oncoming storm, lowering peak wind speeds and storm surge heights. The system would not prevent hurricanes from making landfall, and it would probably need to be deployed for most of the year, not just when a storm is imminent. Preliminary calculations suggest that it could reduce the strength of cyclonic storms substantially, perhaps weakening a category five hurricane to a category four or three—and thus preventing billions of dollars of damage and the cost of human lives lost.

Do you have plans to build or deploy the Salter Sink any time soon?
Our focus is on invention, not on product deployment. That doesn’t mean we don’t prototype our ideas and take them some of the distance, but the final solution – especially in the case of the Salter Sink – is beyond our charter. Here in the lab we have done some experiments and computational modeling work to validate this idea, but a lot more research needs to be done by experts in related fields such as climate science and oceanography, and we need partners to pursue the project further. Our hope in publicizing this invention is to suggest that practical defenses against at least some catastrophic storms may be possible, and to encourage more systematic research and invention in this area.

Why hasn’t anyone else thought of this idea?
This general approach is not a new idea: a company named Atmocean (not affiliated with Intellectual Ventures) has fielded prototype versions of a system that would use wave-driven pumps to lift deep, cool waters up to the surface, as a way to improve ocean fertility and CO₂ absorption.

Over the years, many ideas have been advanced for technological approaches to weaken or dissipate hurricanes that threaten major population centers. So far these ideas have generally been considered impractical [Landsea 2007], in most cases because they are simply inadequate to address the phenomenal power packed into cyclonic storms, which is measured in the trillions of watts [Emmanuel 1998].

What are the risks?
A great many questions still remain to be answered about the practicality of this invention. One key issue has to do with subsurface currents, which in some areas of the ocean create strong shear forces that would deform the tube of a Salter Sink or even tear it apart. Another question we have explored, through simulation and laboratory experiments, is just how efficiently Salter Sinks of various sizes would cool the surrounding warm layer of surface water.

As with other geoengineering technologies, there is also the difficult question of who would pay for construction, deployment, and maintenance of a coastal protection system. Tsunami warning systems, already widely used in coastal zones, offer one possible model. Although a system to suppress hurricanes would likely be far more complex and expensive, it would also offer greater and more frequent protection. A third-class of questions surrounds the possible environmental effects of increased mixing between surface waters and mid-waters.

For more information please check out these related blog posts “Introducing the Salter Sink” and “Our Answers about Geoengineering,” and the Salter Sink Whitepaper.

Energy from the sun heats up the surface of the ocean.  As that heat irradiates up and fuels storms, they can become ever more dangerous hurricanes.  Reducing their destructive potential is possible if we can just cool off the surface of the ocean.  Even just one degree centigrade might be the difference between a category 4 or category 5 hurricane.  This is a nearly ridiculous notion because of the scale involved.  Thousands of square miles of ocean surface might need to be cooled off.

The Salter Sink is a simple idea, with massive potential.  Two insights make it very compelling:

Everywhere there is hot water on the surface of the ocean, there is cold water down below.

This makes us think you just need to stir the ocean up a little bit.  Of course, that too would take a staggering amount of energy, but…

There is a tremendous amount of energy available – in waves.

Wave energy is often dismissed as impractical to use because it is located far from people (where we need energy).  It is also difficult to harness because of the harsh conditions equipment would have to sustain.

The Salter Sink works as a wave powered pump.  Waves push hot water into the top of the cylinder, which pumps the water inside down.  It comes out the bottom (around 200 meters below) and mixes with colder water.  This brings the temperature on the surface down over time.  A Salter Sink can move about a gigawatt of thermal energy!  It may take thousands of these to protect America’s Gulf region (for example) but we estimate the cost would be much lower than the damage caused by one of these storms.

This concept is delightfully simple and singularly gargantuan. It has captured our imagination here in the lab for a couple years, and we hope lots of other folks will find it interesting as well. This movie illustrates the idea, and we also have a Salter Sink White Paper with more detail.

High quality m4v video.

In the mean time, I’d like to point out that we aren’t building this device, and have no plan to. We are exploring ideas to solve the world’s hard problems in energy and climate issues, and need lots of other folks to research them too before they can be considered for deployment.

We’re looking forward to discussing these ideas and will post more about them here later this year.