Ocean CO2 Capture-William Hall
See my prior posts over the last few days on ocean fertilization and farming for the capture and sequestration of carbon. ~half the surface of the oceans of the world is basically desert because there is so little iron and/or magnesium available that phytoplankton can't make enough chlorophyll to survive. Supplying these trace elements in micronutrient quantities seems to be sufficient to make these areas literally bloom. It remains to the 'farmers' to seed the fertilized areas with optimum mixes of phytoplankton and zooplankton to maximize the carbon captured; and then to add and manage suitable suites planktivores and higher order predators to package the captured carbon in fecal pellets and carcases that will rapidly sink to the ocean floor before the captured carbon can be recycled into CO₂. Some of the premium animal protein can be harvested as fish-fillets, etc. to replace the need for dedicating vast areas of arable land surface to farming animal protein. In turn, this would allow revegitation and farming to optimize carbon capture and sequestration on land. Of all the schemes I have seen more thermodynamically, physically, logistically, and economically practical than any other proposal I have seen. Except for the need to refit converted fossil fuel transporters with wind/photovoltaic propulsion to make them green, most of the required infrastructure already exists in the soon to be redundant fossil fuel and mining industry. Deployment could be started on a large pilot scale within a year. Might not be terribly efficient from year one, but at least some carbon would be captured with efficiencies to increase rapidly through trial and error learning as well as guidance from controlled experimentation. A further advantage is that this system comes equipped with a built-in emergency switch. If it shows signs of going awry turn off the micronutrient taps to starve it to a stop as the residual chlorophyll carries trace elements to the bottom along with the last of the captured carbon.
Over the last few years there has been increasing evidence that the temperature-related rates of 'natural' greenhouse emissions from soils, wildfire, burning peat, thawing permafrost above and below current sea level, newly exposed areas of previously ice covered ocean, etc. are growing faster than anything humans have done to reduce emissions. Aside from increasing greenhouse gas concentrations, several other factors (e.g., reduced snow cover and ice melting) also contribute positive feedback to global warming. If humans cannot very quickly manage to stop and reverse the warming, the speed will have ramped up past the point where where readily available carbon has burned up (i.e., including dead organic matter and humans along with most of the terrestrial biosphere). There are three broad categories of things we can do towards reversing the warming: immediately stop all anthropogenic greenhouse gas emissions (methane is the most urgent); draw down, capture and safely sequester existing GHGs atmosphere; and increase our planet's ability to reflect solar energy (i.e., increase albedo). The latter processes would have to be implemented at geoengineering scales to have any hope of working. Given that several geological scale processes involving positive feedbacks with global temperature are already operating and building inertia, I doubt that stopping anthropogenic GHG emissions on its own will do more than temporarily slow the rate of GHG emissions -- requiring the successful implementation of at least one of the geoengineering solutions. Given that negative consequences of most of the proposals for significantly altering Earth's reflectivity seem to outweigh any possible benefits, they would seem to be very last resort options. For a while I have been researching proposals for capturing and sequestering carbon. Several mechanical and chemical processes work in lab-bench tests or even at pilot scale but seem totally implausible or even impossible to have a net benefit when scaled up to a global scale due to unfavorable economic/logistical/production issues, thermodynamics, or resource requirements. Biological approaches seem to be practical winners on all grounds - including the probability of being able to capture and sequester enough greenhouse carbon to allow our planet to actually begin cooling. The article linked here provides very significant observational data from peer-reviewed science validating at least part of the proposal.
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In 1990, the oceanographer John Martin proposed that the Southern Ocean is starved of iron, and that deliberately seeding its waters with the nutrient would allow phytoplankton to grow. The blooming plankton would soak up carbon dioxide, Martin argued, and cool the planet and slow the pace of global warming. Researchers have since tested this idea in 13 experiments, adding iron to small stretches of the Southern and Pacific Oceans and showing that plankton do indeed flourish in response. Such iron-fertilization experiments have typically been billed as acts of geoengineering—deliberate attempts to alter Earth’s climate. But Savoca and his colleagues think that the same approach could be used for conservation. Adding iron to waters where krill and whales still exist could push the sputtering food cycle into higher gear, making it possible for whales to rebound at numbers closer to their historical highs. “We’d be re-wilding a barren land by plowing in compost, and the whole system would recuperate,” says Victor Smetacek, an oceanographer at the Alfred Wegener Institute for Polar and Marine Research, in Germany. (Smetacek was involved in three past iron-fertilization experiments and has been in talks with Savoca’s group.)
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09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)~~ Ocean fertilization and farming to capture greenhouse carbon and sequester it as sea-floor sediments 09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)09:53, 6 November 2021 (MDT)~~ Facts: approximately half of the surface area of the world's oceans is a desert for photosynthetic (i.e., carbon fixing) algae because there are not enough atoms of iron (and/or sometimes magnesium) to support the formation of functional chlorophyll required to capture the energy of light needed to drive the formation of carbohydrates from water and CO₂. Photosynthetically formed carbohydrates provide virtually all of the food and building blocks of the biosphere. Proposal: Fertilization: As long as the resources the algae require (e.g., traces of iron and magnesium, larger quantities of nitrogen, calcium, phosphorus, sulfur, etc) are available in the water around them, algae multiply prodigiously until they begin using up other limiting nutrients that may also be scarce (but much more abundant than iron and magnesium) in the desert zones. The required C is generally fairly abundant in the form of carbonic acid everywhere in the oceans because water has an affinity to absorb CO₂ from the atmosphere to form the acid. Given that iron and magnesium are micronutrients, that only need to be present at parts per billion or million, mining, transporting and dispensing limiting nutrients over large areas of ocean should be logistically feasible. At least at the outset, it should also be economically feasible to refit soon to be redundant fossil fuel bulk carriers and tankers to dispense iron/magnesium dusts or solutions (e.g., as chlorides, acetates, nitrates, sulfates, etc. that might work better as fertilizers). Given no economic need for fast port-to-port transit, the fertilizer dispensing ships could also be refitted for all-electric wind/solar photovoltaic propulsion. Farming: Farming has the goal to maximize and optimize the resulting phytoplankton growth and the expanding ecosystem this will support to condense and package the maximum tonnage of carbon into parcels (e.g., feces and dead organisms) that are dense and large enough to fall into the ocean depths and add to the sediment on the sea floor before their carbon content can be recycled as CO₂. Farming would involve seeding fertilized areas with selections of phytoplankton, zooplankton, and larger consumers ranging from various kinds of 'jellies', 'bait' fish, pelagic carnivores (e.g., tunas & sharks), and even whales (see linked article!). It is possible that the capture of carbon could be multiplied further by harvesting a proportion of the larger fish for premium animal protein, with the offcuts and offal allowed to rapidly settle to the ocean floor. The harvested protein would then be used to replace much of the farming of land animals for protein -- allowing the agricultural land devoted to animal protein production to be revegetated and optimized for carbon capture and sequestration. It may also be feasible to make the fleets of boats required for farming activities carbon neutral through electrification, and refitting a proportion of the surplus fossil fuel carriers as mobile charging stations for the fleets. Imagine a refitted container vessel surrounded by a floating network of deployable/retrievable, solar arrays able to fold down to the size of a standard container for transport and storage, and unfold when deployed. Obviously it will take a lot of research and experimentation to sequester the maximum tonnage of carbon per year, but even initially, some carbon will be captured and sequestered. Even with all the likely savings and pay-backs, such a project will be very costly and labor intensive (interesting and satisfying jobs here for anyone and everyone). However, when compared to proposal I am aware of it should cost less and have a higher chance of actually working when expanded to a truly global scale (if repurposing land-based animal agriculture is included - this would be MORE than a quarter of the total planetary surface engaged in carbon capture and sequestration). Finally, people worry greatly that doing anything at a global scale represents major risks if something goes wrong. However, unlike many other proposals (e.g., for albedo control) this has a fairly conspicuous 'off switch'. If the ecosystem goes too far out of control, stop fertilizing it, and what's left in the system will soon enough fall to the bottom along with the starving remnants of the ecosystem, thus returning the surface waters to their previous desert state.
