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Julian D. A. Wiseman
Abstract: To cool the planet just add sulphur to a tame tethered tornado.
Publication history: only at www.jdawiseman.com/papers/environment/planet_cooling.html. Usual disclaimer and copyright terms apply.
Contents: Introduction; Idea 1: Albedo Enhancement; A Tame Tethered Tornado; Sources of Sulphur; Next Steps; Afterword.
This proposal puts together two separate ideas to make a planet-cooling machine.
The first is that injecting sulphur into the stratosphere would increase the earth’s reflectivity (‘albedo’), thereby reflecting some incoming solar energy.
The second is that it is possible to build an artificial tame tethered tornado, which could be used to carry the sulphur from the ground to an altitude of 10km+.
The first idea is due to Paul J. Crutzen, the Nobel prize winning specialist in atmospheric chemistry. His 2006 essay, Albedo Enhancement by Stratospheric Sulfur Injections (PDF of full text), proposes adding sulphur to the stratosphere (so, to an altitude of at least ≈10km). There the sulphur would become sulphate, which would increase the earth’s albedo. Reflecting a little sunlight would compensate for the heat retained by greenhouse gases. Crutzen proposes “continuous deployment of about 1–2 Tg S per year”.
This can be achieved by burning S2 or H2S, carried into the stratosphere on balloons and by artillery guns to produce SO2. … In the stratosphere, chemical and micro-physical processes convert SO2 into sub-micrometer sulfate particles. This has been observed in volcanic eruptions e.g., Mount Pinatubo in June, 1991, which injected some 10 Tg S, initially as SO2, into the tropical stratosphere (…). In this case enhanced reflection of solar radiation to space by the particles cooled the earth’s surface on average by 0.5°C in the year following the eruption (…). Although climate cooling by sulfate aerosols also occurs in the troposphere (…), the great advantage of placing reflective particles in the stratosphere is their long residence time of about 1–2 years, compared to a week in the troposphere. Thus, much less sulfur, only a few percent, would be required in the stratosphere to achieve similar cooling as the tropospheric sulfate aerosol (…). This would make it possible to reduce air pollution near the ground, improve ecological conditions and reduce the concomitant climate warming. The main issue with the albedo modification method is whether it is environmentally safe, without significant side effects. Locally, the stratospheric albedo modification scheme, even when conducted at remote tropical island sites or from ships, would be a messy operation.
Burning a million tons of sulphur per year would indeed be “messy”. What is missing is a cheap way to lift up the sulphur by 10km. The BBC, in Creating a 'sulphur screen', cites Professor Crutzen as wanting to use rockets.
But Professor Crutzen does not want to wait for another volcano.
Instead, controversially, he wants to duplicate the effects of volcanic eruptions and create a man-made sulphur screen in the sky.
His solution would see hundreds of rockets filled with sulphur launched into the stratosphere. He envisages one million tonnes of sulphur to create his cooling blanket.
"Hydrocarbons are burnt to lift the rocket material, and the rocket then goes into the stratosphere. In the stratosphere, hydrogen sulphide is burnt, and the sulphate particles reflect solar radiation," he explains.
But, alas, that many rockets would be expensive, and probably too expensive.
Let us also eliminate a different obvious plan: a tall solid chimney. Ignoring wind and earthquakes, to avoid buckling a concrete chimney 10km tall would have to have a radius of ≥200m, so a volume of at least 1¼ cubic kilometres, or 46× the quantity used to build the Three Gorges Dam, the structure with the record for the largest amount of concrete used. That is a lot of concrete, and it isn’t obvious how to build the top few miles of the chimney. So this seems to be impractical.
But, happily, an idea intended to be used for power generation could do the task.
The second idea is due to Norman Louat and Louis M. Michaud, to whom it reportedly occurred simultaneously, and this explanation is derived from the latter’s VortexEngine.ca.
Air vortices form naturally and simply: a water temperature of 30°C is sufficient to generate a hurricane. Likewise one can generate a vortex artificially, given a source of heat and some spin applied at the base. The spin can be produced by allowing hot air through angled air entries into a partially-roofed circular chamber. The angled entries generate spin; the heat of the air causes it to rise through the hole in the roof, drawing more air into the chamber and thus generating more spin. As the vortex grows it functions as a chimney, drawing air from the base to the top.
The inventor is selling this for power generation, using as a source of heat the hot water that would otherwise be left to sit in a cooling tower. He claims that using this waste heat would increase a power station’s “power output by up to 40% without any increase in emissions”. With the design optimised to generate power through the turbines in the angled air entries, the following parameters are given.
- Circular wall diameter 50 to 200 m
- Circular wall height 30 to 80 m
- Vortex base diameter 20 to 100 m
- Vortex height 1 to 20 km
Note the estimated vortex height. There are three obvious means of control of the vortex, by which a height of ≥10km could be maintained. First, the airflow into the circular chamber can be constricted, allowing any airspeed up to the hardware’s maximum. Second, the temperature of the incoming air can be lowered by pre-mixing it with non-warm air. Third, the humidity of the air could be increased by spraying warm water into it. Also, it might be possible to add other small-scale aerodynamic controls. Testing is required to know whether this would be enough control to maintain a stable vortex that does not leak sulphur into the lower atmosphere.
However, the vortex engine is the subject of a patent. It is assumed that the patent holders would be nice to those attempting to save the planet.
The final machine will need to lift a lot of sulphur: 1 Tg S per year ≈ 2 tonnes per minute. The following quotations are taken from reports published by the U.S. Geological Survey; the first the 2009 Mineral Commodity Summary; second the 2007 Minerals Yearbook.
… Elemental sulfur production was 8.4 million tons; … Elemental sulfur was recovered, in descending order of tonnage, at petroleum refineries, natural-gas-processing plants, and coking plants
Worldwide recovered sulfur output is expected to increase significantly. For the next 1 or 2 years, sulfur supply was expected to nearly equal demand. Severe sulfur surpluses, however, were expected beginning in 2010, accelerating thereafter as a result of increased production, especially from oil sands in Canada, natural gas in the Middle East, expanded oil and gas operations in Kazakhstan, and Venezuela’s heavy-oil processors. Additional production increases were expected to come from Russia’s growth in sulfur recovery from natural gas and Asia’s improved sulfur recovery at oil refineries. … An in-depth analysis conducted by Black & Veatch … predicted that sulfur recovery from global petroleum refineries could reach 50 Mt in 2025.
Currently sulphur costs from as much as ≈$40 per ton down to nothing (please, if you don’t take it away then we’ll have to store it). There are tens of millions of tons of blocks of elemental sulphur stored in North America, so it should be possible to obtain a million tons a year at moderate cost.
This has never been done before. Things need testing and prototyping.
A large-scale vortex machine has never been built.
It would cost only a few million ($ or € or £: the estimate isn’t that precise) to build a circular wall 100m radius and 80m high, with directed air entries and controls, near a source of waste warm water. By the standards of global warming solutions, this is almost free. For a sufficiently tall and stable vortex the machine might need to be larger still—experience can be gained only by experiment.
Will sulphur really cool the planet?
Volcanoes have cooled the planet, and it is believed by this mechanism. But knowing this before committing to the whole project is difficult. So what will the whole project cost? To build the full-size vortex engine perhaps 50 million, and the same again on lawyers’ fees to get permission to start it. To build the factory to make the sulphur in the chosen form add another hundred million, and a bit less each year for sulphurous raw material. Allowing for some approximations and over-runs, a billion a year should be over-budgeting. By the standards of global warming solutions, this is almost free.
What next? Somebody with access to money has to take an interest. Could that be you?
|— Julian D. A. Wiseman|
Paris, 13th January 2010
14th January 2010: By telephone Louis M. Michaud shared two concerns, both about water. First, if water vapour gets high into the stratosphere it can act as a long-lived greenhouse gas. But this should not be a problem with the vortex below 15km. Second, the rising air would inevitably contain some water vapour, and having reached its terminal altitude would almost certainly be saturated with water. So it would rain, and that acidic rain would be geographically concentrated. Hence the sulphur must be in a form that would not be easily washed out by high-altitude rain. This requires expertise in atmospheric chemistry beyond the skill of the the author: help wanted.
These so concern him—the patent holder—that he does not support using the vortex engine for this purpose. Persuasive expertise is needed.
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