Assume for a moment that the silica from tetraethyl silicate in fuel cant be done by burning the mixture a the jet engine and a special burner(possibly a ramjet) has to be used:
This suggestion still seems to be the simplest way of getting a particle of defined size. Aircraft would almost certainly be used at least for initial testing so altitude restrictions apply to all proposals. |Looking at storage and pumping on the ground and on board, the use of all the standard aircraft tanks and pumps seems to have great advantages. Having said that ,all reasonably practical ideas should be taken to the stage of testing the mechanics of implementation. This includes Alvias balloon ideas, your H2SO4 and of course the sea water spraying.The costs of such research and development are trivial in comparison with the problem. john gorman ----- Original Message ----- From: David Keith To: [email protected] ; [email protected] Cc: Ken Caldeira ; [email protected] ; geoengineering ; Wingenter ; Climate Intervention ([email protected]) Sent: Thursday, October 21, 2010 2:04 PM Subject: [clim] RE: [geo] The problem with stratospheric SRM A few comments on microphysics of stratospheric aerosols. We have examine the microphysics in a recent GRL paper. We confirmed earlier findings that the standard SO2 injection can be surprisingly ineffective because most of the sulfur is deposited on existing particles making them too large. We proposed a solution, injecting H2SO4 directly and showed that in the same modeling framework it worked far better than SO2. (Better=less sulfur mass to get same forcing, plus weak ozone surface-area benefits). This can be generalized to other condensable vapors. The paper is enclosed along with slides that may be helpful. N.B., we have reexamine assumptions and discovered an minor error in the original calculation, as it happens the new results make the direct H2SO4 scheme look a bit better, the figure on the slide is the new version. We also reexamined ozone loss, this effort was directed by Thomas Peter, one of the collaborators on the paper who runs a major stratospheric chemistry group. We have examine the engineering with an aircraft engineering group and found no first-order problems (that report will be released soon). I don't think H2S would help. It has the same disadvantage as SO2. Note that Gorman has proposed direct formation of silicates in commercial aircraft exhaust, following earlier suggestions of sulfur in jet fuel. Commercial aircraft don't flight at the right height or location to efficiently deliver materials to the stratosphere. You need to be in the tropical stratosphere get reasonably long lifetimes, this requires altitudes beyond about 18 km. Yours, David From: [email protected] [mailto:[email protected]] On Behalf Of Oliver Wingenter Sent: Sunday, October 17, 2010 7:39 PM To: [email protected] Cc: Ken Caldeira; [email protected]; geoengineering; Wingenter Subject: [geo] The problem with stratospheric SRM Dear Ken, The problem is after the initial injections, i.e. the second yea of GE, can we even create new particles with a background now 15 to 25 times higher with or with out nucleation sites? Under the present sulfate schemes it appears not. in order to "tune in" particle size and number ternary nucleation of sulfate, water and perhaps ammonia (NH3) will probably need top be invoked. Let us remember that water vapor is not finite in the stratosphere and as more particles are produced additional sulfate will be needed to reduce the vapor pressure of the aerosols. An additional species such as NH3 could help over come this limitation. Injection of H2S would lead to greater dispersion of sulfur, allowing more particle growth but is not considered in stratospheric SRM paper to date because the microphysics involved in most modeling studies has not yet been considered. The actual formation of particles in models of the stratosphere as a result of geoengineering has yet to be established. This is it greatest priority of SSRM at this time. Sincerely, Oliver Wingenter On 10/17/2010 3:41 PM, Ken Caldeira wrote: Yes, you could produce even more new particles yourself which would inhibit new particle production from someone else's emissions, but presumably the total particle count would be higher at the end of all of this than if you did not intervene. Would it be possible to act on someone else's particle production in a way that would lower overall particles counts? On Sun, Oct 17, 2010 at 1:50 PM, Oliver Wingenter <[email protected]> wrote: Dear Josh, If the concentration of background particle were large enough, a few hundred particle per cm3, then this would inhibit new particle production. At least this is case in the marine boundary layer. I understand that stratospheric microphysical models are having trouble making new particles. However, adding NH3 would allow ternary nucleation tens of thousands of times faster than sulfuric acid and water alone as is seen in the free troposphere. In terms of a volcanic eruptions like Pinatubo, I wonder how much ash made it to the stratosphere and provided nucleation sites? Sincerely, Oliver Wingenter On 10/17/2010 12:29 PM, Ken Caldeira wrote: Multiple, independent injections would decrease the likelihood of coagulation relative to injecting it all in one place. Of course, there is potential for coordinated injections to decrease coagulation (aggregation) relative to uncoordinated injections. There is no evidence that I know of that one injection could "cancel out" the effects of another injection. It seems that the main case is that the climate effect of A+B would be less than the climate effects of A plus the climate effects of B. It is an interesting research question to understand whether there are countermeasures that would decrease the effectiveness of injection by injecting something upwind from an injection site that would promote aggregation of the injected material. ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected] http://dge.stanford.edu/labs/caldeiralab @kencaldeira On Sun, Oct 17, 2010 at 10:43 AM, Josh Horton <[email protected]> wrote: Hi everyone, I am finalizing a chapter on geoengineering policy for publication and would greatly appreciate informed feedback on the following paragraph: "The aerosol most commonly suggested for stratospheric injection is sulfuric acid. Plans call for delivering sulfate aerosols by dispersing gas-phase precursor materials. Precursor oxidation and aerosol formation involve complex processes with the potential to reduce the effectiveness of stratospheric insertion. For instance, coagulation could lead to excessively large sulfuric acid particles that sediment out of the stratosphere, neutralizing the effect of the initial dispersion. Multiple, independent injections would increase the likelihood of such unintended consequences. Unsynchronized staging, scheduling, and delivery of sulfate aerosol injections would magnify the potential for perverse particulate interactions, and might jeopardize the success of geoengineering deployment. Lack of policy coordination may result in separate injection schemes that effectively cancel each other out." For those with scientific/technical backgrounds, is this a sound argument? Is the basic science correct? I am outside my comfort zone with this and want to be sure I don't miss the mark. Thanks to anyone who can offer insight. Josh Horton [email protected] http://geoengineeringpolitics.blogspot.com/ -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "Climate Intervention" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/climateintervention?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
