Tropospheric Injection of Micro Diatoms
A Combined SRM/CCS Proposal with Long Term Implications for
Enhanced Hydrate Burial and General Ocean Acidification Mitigation
A Brief Conceptual Sketch Offered to the Google Geoengineering Group
Diatoms are ubiquitous to the waters of this planet and they all have self regulating biological features which makes them ideal for GE use on a regional or global scale. It is estimated that there are approximately 2 million species, yet only a fraction have been studied. This proposal does not call out for any particular species. I leave that determination to others. In general, they play an important role on many different levels. Diatoms offer O2 production, CO2 capture and sequestration along with long term hydrate burial. The potential for diatoms to produce biofuel is well known but that issue is outside of this proposal.
Through my discussions with M.V. Bhaskar, I have become aware that micro diatoms can be prepared in a dry form as a means to seed bodies of water to produce artificial diatom blooms for enhanced O2 saturation. This conceptual sketch proposes that this type of material be considered for atmospheric aerosol injection as a form of combined SRM/CCS/Enhanced Hydrate Burial and Ocean Acidification Mitigation.
:A minimum of seven main technical issues concerning this type of biological aerosol medium can be anticipated.
Will this form of aerosol stay suspended for a reasonable time? The size of micro diatoms are such that proper dispersal could produce an aerosol which would stay suspended for a significantly reasonable periods of time. The engineering of the dispersal method is similar to previous aerosol concepts. The suspension time will depend on many factors ranging from altitude of injection, latitude of injection (atmospheric cell characteristics) and general tropospheric weather conditions. The rate (if any) of atmospheric moisture absorption needs further understanding. If it is found that this medium does absorb atmospheric moisture, this could represent a means to reduce that primary green house gas, as well as, possibly providing a means for cloud nucleation/brightening.
Will the diatom aerosol reflect SR? Typically, this diatom preparation is brown. I believe it may be possible that the diatom material can be engineered to be reflective. This might be done through laminating the dried preparation with biologically neutral reflective material (white powdered sugar?). Finding the right laminating material which does not substantially degrade suspension time, seed viability or produce accumulated environmental adverse effects will need investigating along with the associated high volume production needs.
Will the diatom material remain viable through the aerosol phase into the aquatic environment? Tropospheric injection avoids the higher altitude environmental stress issues. Such as, high UV, low ambient pressure and extreme low temperatures, which may effect seed viability. However, the possibility of laminating the material to address the high altitude concerns may also be possible in the future and will need further investigation. The added complications, relative to seed survival, of stratospheric injection indicates that tropospheric injection should be the initial deployment consideration. Stratospheric injection may be avoided if coordinated and tailored regional tropospheric efforts can be developed.
Will this method address arctic ocean methane release? ESAS based tropospheric injection of this medium can have three significant benefits. The first is the immediate SRM benefit (with proper seed lamination, possible cloud nucleation/brightening). Second is the potential enhanced dissolved methane oxidation rate. Third is the enhanced wide area increase in the sediment build up rate over the shallow water hydrate fields.. The ESAS is at a critical edge of the GHSZ envelope. A rapid build up of diatom debris could expand the envelope significantly with just one added meter of diatom sediment ooze (insulation against warming waters, as well as, decreasing the porosity of the existing sediment). That will obviously take a few years to achieve. However, no other practical means to achieve this needed large area effect seems available. Also, can the resident AOM adapt to a marked increase in diatom rain?
Will this method address tundra methane release? Not completely, however this method could seed even the smallest body of standing water within a tundra region and thus provide added O2 saturation and the associated methane oxidation. As the tundra continues to warm, more standing water will emerge and thus this potential enhanced oxidation will become more important.
Will this method have a meaningful/measurable effect on ocean pH levels? Diatoms consume dissolved CO2 and thus it is a matter of scale. There is a need to determine the seed mass ratio to the total CO2 consumption that can be attributed to that seed mass. This will determine the cost effectiveness/scalability of this aspect of the concept. The current use of this diatom seed material does not take into account the aerosol phase being proposed. Seed survival rates during the aerosol phase might be determined through table top experiments, yet field test would be needed to verify any lab data. Field trials for this overall concept should not trigger significant protests as the diatom species which will be used pose no known toxic hazards and are widely considered to be ecologically beneficial.
Will this method be financially competitive with other aerosol concepts? The cost of diatom medium preparation and injection can be expected to be somewhat greater than sulfate/aluminum aerosols. This is due to the potential beneficial aspects of this biological medium after precipitation. The more material used, the greater the overall beneficial effect. That aspect represents a principal departure from that of the prior art. The prior methods seek to minimize cost through use of long lasting aerosols (which have no secondary environmental benefit). The less aerosol used, the less cost (and less potential adverse effects). This proposed method represents a means which generates second and third order ecological benefits once the aerosol precipitates. The added cost of the expected large volume of material to be used should be justifiable due to these important interrelated secondary benefits. This is not just a mitigation effort, it is potentially also a general regional ecological enhancement.
This GE approach offers at least two non global warming mitigation related benefits to society. First would be the overall water quality improvement in the operational area due to the increase in saturated O2 levels provided by the seeded diatom blooms. Second would be that fisheries may improve due to the increase in the marine food production rates at the micro level. If only those two ancillary, yet fundamentally important benefits, can be proven, the debate surrounding GE can be expected to take a new direction.
Note: If this proposal finds any acceptance, M.V. Bhaskar deserves ample credit. I have simply tried to craft his input into conventional GE terms. If it finds no acceptance, I take full credit.
Michael Hayes 6/21/11
Cheers!
Sam Carana
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It is not a safe assumption that anoxia in the water column is a factor in most methane emissions from water bodies. With fossil methane release, oxygenation is unlikely to be of much assistance. Only where methane is produced in the water column in anoxic or hypoxic conditions would this method be likely to assist significantly.
In practical terms, hypoxia is best addressed indirectly, e.g. by controlling fertilizer runoff
Only in stagnant bodies, such as the black sea, would oxygenation be likely to be beneficial. Methanogenesis usually occurs below the photic zone and mixed layer - and mixing of co2 could also be a limiting factor. Therefore biological methods would be unlikely to be effective.
A
I'm not against biological methods, you just can't easily use them for oxygenation - as nature is pretty good this way anyhow.
There are many practical ways to reduce fertilizer use. Stopping perverse farming subsidies is one, taxing fertilizer use is another.
Reducing nox from fertilizer may increase methane residency times
A
How does Agro-Silica benefit plants
Agro-Silica makes plants stronger and healthier
Silica is a primary fertilizing element for rice and grass crops. To produce 100kg of rice yield, rice demands 14.8kg of silica which is 8 times more than nitrogen which is required at 1.8 kg. Most paddy soils have silica deficiencies and require silica to be replenished regularly into the soil. The ideal silica concentration in paddy soil is 130~180 ppm. Research has shown that paddy soil containing silica less than 60 ppm produces unhealthy rice.
Australia
http://www.nutri-tech.com.au/blog/2010/06/silica-the-hidden-cost-of-chemicals/
I'm not doubting that biological methods can produce oxygen.
I'm simply saying that they won't be readily applicable to the dark, still waters where methane is produced.
There are also a lot more efficient mechanical methods than you suggest to oxygenation water. Wave making, flow diversions and impellers are but a few.
A
AndrewWater flows with Nitrogen and Oxygen in it.These do not originate in the depths of the oceans.These originate on the surface of earth and oceans and sinks to the depths.So the biological methods would remove the Nitrogen and increase oxygen at the surface not in the depths.Any mechanical means would require equipment and energy, this would add to GHG emissions even when solar, wind and wave energy are partly used.How do you propose to install mechanical devices in the depths of the oceans?A lot of methane is generated due to human activity on land.Manure, sewage, garbage land fills, rice fields, reservoirs behind dams, etc.Please suggest a solution to this.
>Wave making, flow diversions and impellers are but a few.
These are used only in ponds and small WWTPs.They are more expensive or require more maintenance or require more land, for e.g., fine bubble diffuser aerators are very energy efficient but the ceramic plates or membranes used are expensive.regardsBhaskar