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Biography: Chris Rhodes. www.fresh-lands.com Professor
Chris Rhodes is a writer, speaker and researcher who became involved with
environmental issues while working in Russia during the aftermath...
Thinking Positive - Carbon Capture.
9 Feb, 2009 07:59 pm
In principle carbon capture using regenerative agriculture, ocean seeding/phytoplankton growth, biochar and algae production, coupled with societal relocalisation could become carbon negative to the tune of - 3 Gt of carbon per year, and yield a similar amount of useful biomass. Such simple sums provide temporary cheer but ignore the enormous input of time and energy required to bring them to fruition however.
The two concepts might be combined however, at least assuming there is enough time, and that the EROEI stacks-up. For the moment, however, let's think positive and assume that it does. Proposals for geoengineering always make me uneasy, including the idea of "seeding the ocean". Principally, my disquiet stems from a feeling that all aspects of nature are interconnected and by messing about with one thing, an unforeseen calamity might ensue elsewhere - the butterfly effect, to use a well-known phrase.
However, if phytoplankton could be caused to bloom, say in the Southern Ocean, 1 Gt (billion tonnes) of carbon could be captured annually. It is claimed that regenerative agriculture might sequester around 3 Gt of carbon each year (although there is some dispute about this), and that by 2050, biochar production could account for another 1 Gt of carbon annually. In principle - and this is where the link comes in - the carbon in the soil can stay there and improve its quality, but if the other kinds of captured carbon could be harvested, it might provide a useful potential source of biomass/fuel. Growing algae on a local level - a "village pond" you might call it - could provide energy to replace fossil fuels for local communities, without impacting on arable land.
Since we emit 7 Gt/year of carbon from fossil fuels, the sum comes out something like (in Gt): 7 - 3 - 1 -1 = 2 Gt left to worry about. A cut in fossil fuel use by 50% through biomass curbs that to 1 Gt. Photosynthesis already absorbs around 3 Gt of carbon/year into oceanic phytoplankton and land-based plants, and if localised algal production cuts emissions from oil by another 1 Gt (assuming that we need 1 Gt less since we have that from algal biomass), the combined scheme is carbon negative by -3 Gt/year.
Hence in 40 years this would have cut 120 Gt of carbon from the atmosphere, which would reduce the concentration of CO2 by around 50 - 60 ppm.
Now this is an extrapolation of sums I have seen done and on paper it looks pretty rosy, implying that we can eke-out our oil, gas, coal and nuclear and at the same time bring down the carbon-content of the atmosphere to pre-industrial levels by the end of this century.
What is rarely mentioned let alone costed-in is the lead-in time, the energy costs, the EROEI, the materials, the engineering and so on... that's when it begins to look less rosy.
For example, while I like the idea of biochar, the stated goal by the International Biochar Initiative (IBI) is that we could have 1 Gt/year of carbon being drawn from the atmosphere by 2050. O.K. let's assume that's 40 years time and that there is currently (in Gt terms) about zero biochar being produced currently. Even if we assume a linear growth in the technology, that "wedge" (if you draw a straight line on a piece of graph paper from 0 - 1 Gt on the y-axis up to 40 years on the x-axis) that only accounts for 20 Gt of carbon, or a reduction of about 10 ppm, which is neither here nor there, and the biomass production and processing would be simply colossal when viewed en mass.
That said, if that level is achieved by, and sustained beyond 2050, 1/7th of all carbon (14%) captured per year is significant, and could be a higher proportion if fossil fuel burning has by then been significantly curbed, either deliberately or because we have less of them available. The main benefit of biochar is likely to be in terms of improving soil quality, if it is employed as a soil-amending agent, and thereby reduces demand on water and nutrients like N and P to grow crops. The latter is likely to be particularly significant in parts of the world where the soil is poor, e.g. Africa and Asia. In the U.K. soil tends to be very rich - too rich sometimes - but even here, the incorporation of biochar into the soil would attenuate problems from run-off waters that contain too much phosphate and nitrate.
Regenerative agriculture is somewhat contested in terms of its carbon capture potential, and there is little evidence that we can "seed" the oceans in a practical fashion, or recover the plankton on any significant scale. Indeed, if massive amounts of phytoplankton were to grow through seeding, the emissions of sulphur compounds (H2S, dimethylsulphide etc.) which are oxidised to particulate "sulphate" matter in the troposphere, would have the effect of further seeding cloud formation. This might help to cool the planet through reflecting more sunlight back into space, which sounds good in GW-terms, but it would surely affect rainfall and how the earth-systems distribute water around the planet.
What I can see is that production of biochar and algae on a local level, as part of a programme of lower-energy living could offer some benefits. There is also (for once) the advantage that there are a lot of people on the planet. Hence if a community of 2000 people could catch and sequester 200 tonnes of biochar per year (100 kg/person), 7 billion of us in total could sequester almost 0.8 Gt/year (close to the IBI projection of 1 Gt/year by 2050). However, it is the curbing of energy use that really counts. Back to the village algae-pond. As a total area, we would need around 3200 km2 of ponds to fuel Britain (more of which could be turned to other purposes than personalised transport through relocalisation), that suggests that each village pond would need to be:
3200 km2 x 100 ha/km2/60 million x 2000 = 10.7 hectares for each 2000 person community. It's big but it doesn't sound impossible when broken down like this. The real problem is how to process the algae either by extraction of its oil/transesterification or bulk thermal gasification. It might be simpler to just grow the algae (and other biomass), dry it out and burn it as a source of thermal energy.
All of the above is going to take an awful lot of engineering, hence energy and time, but let's not depressed about the details, and look at those "happy sums" again.
Related Reading.
[1] http://ergobalance.blogspot.com
[2] http://en.wikipedia.org/wiki/Carbon_sequestration
[3] http://en.wikipedia.org/wiki/Carbon_sink
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By the same author
- “Peak Oil” is Nonsense… Because There’s Enough Gas to Last 250 Years.
- Threat of Population Surge to "10 Billion" Espoused in London Theatre.
- Current Commentary: Energy from Nuclear Fusion – Realities, Prospects and Fantasies?
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This is interesting because this rock, if pulverized, could take down all the CO2 man has ever emitted and tuck it inconspicuously into that terrain as magnesium carbonate and silica. This, and not any biologically based scheme, is the most inexpensive and effective way to pull down CO2.
Biotic Carbon, the carbon transformed by life, should never be combusted, oxidized and destroyed. It deserves more respect, reverence even, and understanding to use it back to the soil where 2/3 of excess atmospheric carbon originally came from.
We all know we are carbon-centered life, we seldom think about the complex web of recycled bio-carbon which is the true center of life. A cradle to cradle, mutually co-evolved biosphere reaching into every crack and crevice on Earth.
It's hard for most to revere microbes and fungus, but from our toes to our gums (onward), their balanced ecology is our health. The greater earth and soils are just as dependent, at much longer time scales. Our farming for over 10,000 years has been responsible for 2/3rds of our excess greenhouse gases. This soil carbon, converted to carbon dioxide, Methane & Nitrous oxide began a slow stable warming that now accelerates with burning of fossil fuel.
Wise Land management; Organic farming and afforestation can build back our soil carbon,
Biochar allows the soil food web to build much more recalcitrant organic carbon, ( living biomass & Glomalins) in addition to the carbon in the biochar.
Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth), is gaining widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!
Biochar viewed as soil Infrastructure; The old saw, "Feed the Soil Not the Plants" becomes "Feed, Cloth and House the Soil, utilities included !". Free Carbon Condominiums, build it and they will come.
As one microbologist said on the list; "Microbes like to sit down when they eat". By setting this table we expand husbandry to whole new orders of life.
Senator / Secretary of Interior Ken Salazar has done the most to nurse this biofuels system in his Biochar provisions in the 07 & 08 farm bill,
http://www.biochar-international.org/newinformationevents/newlegislation.html
Charles Mann ("1491") in the Sept. National Geographic has a wonderful soils article which places Terra Preta / Biochar soils center stage.
http://ngm.nationalgeographic.com/2008/09/soil/mann-text
It's what Mann hasn't covered that I thought should interest any writer as a follow up article;
Biochar data base;
http://terrapreta.bioenergylists.org/?q=node
NASA's Dr. James Hansen Global warming solutions paper and letter to the G-8 conference, placing Biochar / Land management the central technology for carbon negative energy systems.
http://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf
The many new university programs & field studies, in temperate soils; Cornell, ISU, U of H, U of GA, Virginia Tech, JMU, New Zealand and Australia.
Glomalin's role in soil tilth, fertility & basis for the soil food web in Terra Preta soils.
Given the current "Crisis" atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?
This is a Nano technology for the soil that represents the most comprehensive, low cost, and productive approach to long term stewardship and sustainability.
Carbon to the Soil, the only ubiquitous and economic place to put it.
Cheers,
Erich J. Knight
Shenandoah Gardens
540 289 9750
In the past 30 years or so the Southern Ocean has been seen to lose 10% of its plant life, the N. Atlantic lost 17%, the N. Pacific 26%, and the sub-tropical tropical oceans 50%. This devastation of ocean plants dwarfs the loss of rainforest plant life and is responsible to the great decline in sea life. Sure overfishing is bad but destruction of the ocean pastures is even more deadly.
ONLY the replenishment of mineral micronutrient iron might restore the oceans to the state of heatlh they were some 30 years ago. At that time the natural ocean plant photosynthesis fixed 4-5 billion tonnes of CO2 each year preventing if from becoming acidic death and instead becoming ocean life. That is half at least of the global CO2 problem.
That carbon bomb impacting the ocean is already so deadly that even if we do not emit a single additional molecule of CO2 the carbon bomb will still destroy higher life in the oceans. No number of energy efficient light bulbs, hybrid cars, or other emission reductions will make one whit of difference if we do nothing to stave off the effects of that carbon bomb already airborne and impacting. Reports in leading science journals note that ocean CO2 saturation is decades more advanced than thought even a year ago. The Southern Ocean is at saturation now and will be beyond help by the year 2030. The N. Pacific has been shown to be in worse condition with acidification proceed at a rate 20 times faster than previously reported.
Think of energy conservation and emission reduction in the absence of ocean eco-restoration like this. It is as if we require accident victims arriving in hospital emergency rooms to take drivers education classes before we staunch thier bleeding and tend to thier lethal wounds even though doing so will surely mean the patient will die.
(1) C.R.L. Cowan's comment reminds me of John Haymaker's book "Remineralize the Earth" which effectively proposes grinding up rock and using that rock dust to fertilize soil, so that it takes-up CO2 from the air in the form of better crop yields. The idea is that this simulates the natural processes where rock is ground by advancing glaciers during ice-ages but the enriched (remineralized) soil is then exposed during the interglacial periods. I think that both notions would in practice take an awful lot of energy to do in practice.
(2) Biotic carbon may be "sacred" and there is much to be recommended in using natural approaches such as regenerative agriculture which it is claimed could absorb 40% of all human carbon emissions. Biochar has many advantages in terms of amending soil, so that it is more fertile, and also retains water and nutrients like N and P thus reducing the demand on them in the first place. This is significant since water and also phosphate fertilizer are likely to be under increasing pressure of demand. If the char itself is sacred and should not be used as fuel, the production of char also generates gaseous and liquid components that could be used as fuel or as chemical feedstocks. Biochar is also a relatively inert form of carbon and a good way to lock-up carbon for hundreds or thousands of years thus removing it from the carbon-cycle in effect. However, to produce biochar on the scale that is being talked about would require vast amounts of engineering and I am suggesting this might be best accomplished as a summation of small-scale enterprises rather than huge centralised installations.
(3) I take the point about reducing the acidity of the oceans by CO2 removal from them. However, fertilization using iron would need to be done on a huge scale and it has not been demonstrated that the iron can be kept in solution as it were, for more than a few days/weeks. There are also issues that the presence of such "additives" might themselves compromise the ecosystems, so it is an unproven strategy.