Hi Folks,
This is a conceptual sketch on the use of a biological aerosol. It is a very
raw concept, yet I found it an interesting thought.
*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.
1.
*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.
2.
*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.
3.
*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.
4.
*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?
5.
*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.
6.
*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.*
7.
*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
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