Biochar as geoengineering

[eclipse]

Hi all,
discussion came up in another thread about whether or not biochar was a successful way to sequester carbon away for long periods of time. Well, like many things in science, it depends.

Scientific research, as well as empirical observations and testing of the terra preta (dark earth) fields in the Amazon areas mentioned above, indicates that biochar (recalcitrant carbon) resists degradation in soil and can persist in soil for hundreds or thousands of years. Scientific testing, however, has shown a staggering variance of biochar’s persistence in soil, which can range from “5 to 8,000 years,” according to soil scientist Dr. Johannes Lehmann of Cornell University.3 Persistence can depend on a number of factors, including the type of feedstock used, the temperature of the pyrolysis process that can vary from 450 to 700 degrees Celsius, the particle size of the biochar, etc. Clearly, muchmore research needs to be done to fully understand this process. Nevertheless, studies indicate that as much as 1.8 gigatons of carbon could be sequestered globally annually through widespread biochar applications.
From the 2013 Sonoma biochar Initiative citizen science project final report

34 page PDF will download if you click tiny url below
tinyurl.com/lh9uul2

[Roger Clifton]

Eclipse, you say that biochar may be a successful way to sequester carbon away for long periods.

To protect the greenhouse, the carbon would have to be locked away for good, with 90% or so still locked away after thousands of years. But insignificant amounts have been sequestered so far. Traces of biochar still persisting in the soil after 8000 years might be of interest to archaeologists, but would be negligible help to the climate.

Do you have a link to the "studies that indicate" that 1.8 Gt/a C could be put away? I suspect that these studies are little more than somebody scribbling with guesses on the back of an envelope, failing to account for the rate that its carbon returns to the greenhouse.

[David B. Benson]

Compressed biochar is almost indistinguishable from the highest grade anthracite coal. It'll stay buried as long as buried deep enough.

[Roger Clifton]

DBB says that biochar would resemble anthracite if sufficiently compressed.  I guess he means, if buried deep enough.

Both biochar and anthracite start out as vegetable matter, a mixture of cellulose and lignin, polymers of HCOH. Most of the cellulose volatilises early in both cases, as C1 and C2 (*) species in pyrolysis, or as the biogenic C1 gases (of CO2 and CH4) if buried unburnt. And that's about half your carbon for a start, returned to the atmosphere.

In pyrolysis, the lignin also gives off C1 and C2, the charring causing increasing cross-linking of the carbon atoms, so that nonvolatile tars of high carbon number remain in the char. Largely these are unstable molecules. When char is buried microbes attack the remaining aliphatic sections of the molecules, continuing to release C1. In the shrinking residue, aromatic (ring structures, often of six carbon atoms) species accumulate. Typically toxic, they are probably the cause of the persistence of biochar noted by archaeologists. The common claim that biochar improves the soil seems dubious in that light.

Anthracite is coal that has been buried so deep and tight that gas hardly escapes, methane generating bugs are suppressed, instead hydrogen slowly leaks away. Anthracite is noted for its ring structures and many-carbon molecules including anthracenes. But the depth required must be in kilometres, not practical for gigaton burial.

(*) C1 molecules have one carbon atom and include CO2 and CH4, formic acid, formalin, methanol. C2 molecules have two carbon atoms and include ethane, ethene, ethanol, acetic acid and so on. When they appear in the soil, they soon return to the atmosphere.

[eclipse]

May 29, 2014 9:12:30 GMT 9.5 Roger Clifton said:

Eclipse, you say that biochar may be a successful way to sequester carbon away for long periods.

To protect the greenhouse, the carbon would have to be locked away for good, with 90% or so still locked away after thousands of years. Traces of biochar still persisting in the soil after 8000 years might be of interest to archaeologists, but would be negligible help to the climate.

8000 years is a long time. A very long time.

By then, although I haven't done the math, biochar advocates would probably WANT some of that carbon back in the atmosphere! If biochar can even sequester away 5% of today's annual emissions, and our energy sources became carbon neutral over the next few decades, surely in 2000 years we would have completely stored the last century's emissions in the soil? Given that fossil fuel use reduces exponentially the further we go back, the 1800's emissions will be dumped into the soil in no time. What's going to happen if we have a massive biochar industry locking away all our carbon 3000 years down the track? 4000? 7000? Hopefully there will be some leakage, so that the biochar industry doesn't eventually crash us into some kind of low-carbon ice age!?

Do you have a link to the "studies that indicate" that 1.8 Gt/a C could be put away? I suspect that these studies are little more than somebody scribbling with guesses on the back of an envelope, failing to account for the rate that its carbon returns to the greenhouse.

The links to the studies are all on en.wikipedia.org/wiki/Biochar#Carbon_sink and would of course depend on assumptions and models, like much of climate science. But the 'scratching away on the back of an envelope' fails to demonstrate an awareness of how serious soil scientists are in their research or the level of thinking that has been applied to this subject. It's as patronising as someone turning around and making the same attack on, say, the calculations that demonstrate the thousands of years we could run the world on uranium in IFR's.

The burning and natural decomposition of biomass and in particular agricultural waste adds large amounts of CO
2 to the atmosphere. Biochar that is stable, fixed, and 'recalcitrant' carbon can store large amounts of greenhouse gases in the ground for centuries, potentially reducing or stalling the growth in atmospheric greenhouse gas levels; at the same time its presence in the earth can improve water quality, increase soil fertility, raise agricultural productivity, and reduce pressure on old-growth forests.[18]

Biochar can sequester carbon in the soil for hundreds to thousands of years, like coal.[19][20][21][22][23] Such a carbon-negative technology would lead to a net withdrawal of CO2 from the atmosphere, while producing and consuming energy.”[citation needed] This technique is advocated by prominent scientists such as James Hansen, head of the NASA Goddard Institute for Space Studies,[24] and James Lovelock, creator of the Gaia hypothesis, for mitigation of global warming by greenhouse gas remediation.[25]

Researchers have estimated that sustainable use of biocharring could reduce the global net emissions of carbon dioxide (CO
2), methane, and nitrous oxide by up to 1.8 Pg CO
2-C equivalent (CO
2-Ce) per year (12% of current anthropogenic CO
2-Ce emissions; 1 Pg=1 Gt), and total net emissions over the course of the next century by 130 Pg CO
2-Ce, without endangering food security, habitat, or soil conservation.[26]

Biochar is a high-carbon, fine-grained residue which today is produced through modern pyrolysis processes. Pyrolysis is the direct thermal decomposition of biomass in the absence of oxygen to obtain an array of solid (biochar), liquid (bio-oil), and gas (syngas) products. The specific yield from the pyrolysis is dependent on process conditions, and can be optimized to produce either energy or biochar.[27]

[David B. Benson]

By compressed I mean that the biochar is squeezed hard enough to eliminate all the nanostructure gas passage ways. Then there is no way for micro-organisms to attack it.

[eclipse]

Why are the long time scales still questioned?

Thus, the overall natural cycle is carbon neutral. In contrast, pyrolysis can lock up this atmospheric carbon as biochar for long periods (e.g., centurial or even millennial time scales). Therefore, the biochar approach is an attractive solution to alleviating global warming concerns. James Lovelock, famous for his Gaia hypothesis, is now advocating biochar as "One last chance to save mankind".

www.istc.illinois.edu/research/biochar.cfm

Dr Evelyn Krull from CSIRO Land and Water:"Biochar has been suggested to be stable over centuries up to millennia, so that makes a big difference," she says.

www.abc.net.au/science/articles/2009/03/04/2507270.htm



Why are the potential quantities still being questioned?

A CSIRO report released last month found that there was a global potential for one billion tonnes of carbon a year to be sequestered using biochar within 30 years.

That's a significant amount, isn't it? 1/8th or 1/9th of anthropogenic emissions? Assuming we hit a carbon neutral energy system, and assuming we hit 1 billion tonnes a year, it's only 800 or 900 years until we've mopped up the majority of the damage. A little 'leaking' of biochar carbon back into the atmosphere over the centuries is not going to undo this project.


Also interesting: it prevents Nitrous and Methane emissions
From the wiki:

"Modest additions of biochar to soil reduce nitrous oxide N
2O emissions by up to 80% and eliminate methane emissions, which are both more potent greenhouse gases than CO
2.[36]"

en.wikipedia.org/wiki/Biochar#cite_note-36

From ABC's Catalyst

Narration: Adding up to 10 tonnes of agrichar per hectare reduces the amount of carbon dioxide given off while tripling the weight of the crop or its biomass.

As well as that they measure another gas that’s important for global warming, nitrous oxide.

Dr Lukas van Zwieten: Certainly nitrous oxide is a very serious greenhouse gas, it’s 310 times more potent than carbon dioxide in the atmosphere.

One of the things that really was quite surprising – we didn’t expect it – was that the emissions of nitrous oxide from soil were significantly reduced.

www.abc.net.au/catalyst/stories/s2012892.htm

[Roger Clifton]

Eclipse... Yes, I am "unaware", I am unaware of any serious studies that say it's feasible to put away 1.8 Gt/C for good. As I say, give us a link ( a direct link!) to a peer-reviewed paper so we can read it.

The closest I know of, and probably source of the rumour, is - www.nature.com/ncomms/journal/v1/n5/full/ncomms1053.html
which assumes a residence time of 300 years, and a world-wide regime that requires every farmer and forester to deliver their by-products to the local biochar/biofuel factory to achieve a net reduction of 1.8 Pg/a of CO2 (not C) emissions. While the regime lasts that is, after which the last 300 years worth returns to the greenhouse.

That reduction is less than 5% of current emissions, less than 3 years accumulation, maintained in a continuing operation like bailing a leaky boat.

Only if all fossil carbon fuels were replaced in some Hanson-esque scenario, biochar might be credible in a desperate attempt at recovery of the damaged greenhouse. Otherwise it is just a token reduction, providing an excuse for business as usual.

Spin doctors love to distract us with token reduction schemes, just this sort of stuff. It's like they're saying "don't worry about the CO2, we put it in fizzy drinks". Let's not fall for their spin, it is patronising!

[eclipse]

Point 1: Normal biochar enthusiasts wouldn't ever deny the need to move to clean energy, fast. I don't know of any Koch-brother's agents funded to subvert the biochar meme to become 'now we don't have to do anything about clean energy', but I wouldn't put it past them. But with people like Hansen backing it, I'm in.

Point 2. References

Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant sink of atmospheric CO2. In order to fully evaluate the influence of BC on the global C cycle, an understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC-containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61–80% lower (P < 0.05) CO2 evolution per unit C over 532 days compared to their respective adjacent soils with low BC contents. No significant (P > 0.05) difference in CO2 respiration per unit C was observed between Anthrosols with contrasting ages of BC (600–8700 years BP) and soil textures (0.3–36% clay). Similarly, the molecular composition of the core regions of micrometer-sized BC particles quantified by synchrotron-based Near-Edge X-ray Fine Structure (NEXAFS) spectroscopy coupled to Scanning Transmission X-ray Microscopy (STXM) remained similar regardless of their ages and closely resembled the spectral characteristics of fresh BC. BC decomposed extremely slowly to an extent that it was not possible to detect chemical changes between youngest and oldest samples, as also confirmed by X-ray Photoelectron Spectroscopy (XPS). Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, the BC-rich Anthrosols had higher proportions (72–90%) of C in the more stable organo-mineral fraction than BC-poor adjacent soils (2–70%), suggesting some degree of physical stabilization.

www.tandfonline.com/doi/abs/10.1081/E-ESS-120045010#.U4pqpi9jAXM

"13,000 years in deep-sea environments (Masiello and Druffel 1998) and was found to have a mean residence time of 10,000 years in soils (Swift 2001)"

Page 164 at link below
www.sciencedirect.com/science/article/pii/S0016703708005875

4.3. Stability of BC

[33] The higher level of mineralized OC on a soil basis (mg g−1 soil) found in the BC-containing soils compared to the adjacent soils indicates that there is no observable limitation on potential biological activity in the BC-containing soils by factors other than OC quality. Indeed, not only higher biological activity, but also higher reproduction rates and greater bacterial species richness and diversity can be found in BC-containing soils [Pietikäinen et al., 2000; Steiner et al., 2004; Kim et al., 2007]. However, on an OC basis (mg g−1 soil OC), only a small fraction of the OC was mineralized in the BC-containing soils, significantly less than in the adjacent soils. Similar low levels of mineralized OC have only been reported when soils were incubated under conditions that reduce microbiological activity, such as low temperature [Rasmussen et al., 2006], water deficiency [Kelliher et al., 2004], or anaerobic conditions [Bridgham et al., 1998]. This was not the case for this study since optimum temperature and moisture were maintained throughout the entire incubation.

[34] Based on the double-exponential model for fitting C mineralization kinetics, the BC-containing soils have a higher amount of recalcitrant OC and also a longer half-life (60 years on average) than the adjacent soils (9 years on average). The half-life of OC in BC-containing soils is affected by both non-BC and BC organic material. Assuming that the half-life for non-BC organic materials in the BC-containing soils is the same as in the adjacent soil, then the half-life for BC in the BC-containing soils should be longer than the average of 60 years calculated for the mixture of BC and non-BC. Depending on the proportion of BC, which may amount to more than two-thirds of the OC (72% estimated by the difference in OC between BC-containing and adjacent soils from Table 2) but was not directly determined, the half-life for the BC portion may then calculate to 80 years at 30°C and optimum water content. In the natural environment, the decomposition of BC is expected to be slower than in our laboratory incubation, due to temperature and moisture conditions that are less conducive to optimum decay as well as due to less physical disruption and thus greater stability of OC. Assuming a Q10 of 3.4 as estimated above, the half-life of BC at a site with 10°C MAT may be as high as 925 years. Due to systematic overestimation of long-term BC decay by short-term incubations [Lehmann, 2007b], the true half-life of BC is most likely greater than calculated here. This agrees well with the C-14 ages of BC which have been reported to lie in the hundreds to thousands of years [Pessenda et al., 2001; Schmidt et al., 2002; Gavin, 2003; Krull et al., 2006].

[35] The low OC mineralization rate of the studied BC particles, as well as their solid-state 13C NMR spectra, suggests that the long half-life of the studied BC-containing soils is primarily due to the inherently recalcitrant chemical composition of BC. Low mineralization rates of BC were also reported by Hamer et al. [2004] and Baldock and Smernik [2002]. Their research showed that from 3 to 20 mg C per g C of fresh BC samples were mineralized. In our study, an even smaller portion of mineralized OC (from 0.46 mg to 4 mg per g C) was found than in the cited studies, even though the physically isolated BC particles in our study certainly contained some adsorbed non-BC as shown by Lehmann et al. [2005]. It is possible that compared with BC from forest fire or from domestic use, the BC used in this study (metallurgical charcoal) was produced at a higher charring temperature [Hollindale, 1999] which may lead to a lower chemical and biological reactivity. However, differences as a function of production conditions may be small given the similar NMR spectra of BC produced at different temperatures investigated by Czimczik et al. [2002] and Baldock and Smernik [2002], but warrant further investigation. More likely is that the BC particles investigated in our study had already undergone loss of the more labile fractions of BC that can occur rapidly during the first months of exposure [Cheng et al., 2006].

[36] These results suggest that over time periods studied here the proportion of a more labile fraction of BC may progressively decrease, rather than that the remaining BC becomes more vulnerable to biological decomposition. This conclusion is in contrast to interpretations of the C-14 ages of different BC fractions which showed that older BC was more easily oxidized by chemical treatment indicating that older BC was less stable [Krull et al., 2006]. It is possible that 130 years of BC presence in soil were long enough to remove labile fractions of BC, but not long enough to degrade the most stable fractions of BC to a significant extent. These results also reiterate the point made by Lehmann [2007b] that incubations of fresh BC do not capture the turnover of aged BC which may indeed be up to one order of magnitude slower than fresh BC as shown here.

onlinelibrary.wiley.com/doi/10.1029/2007JG000642/full

[Roger Clifton]

May 31, 2014 6:45:07 GMT 9.5 David B. Benson said:

By compressed I mean that the biochar is squeezed hard enough to eliminate all the nanostructure gas passage ways. Then there is no way for micro-organisms to attack it.

Heck, if we're going to heat and compress it to a hard, inert material, why bury it?

Suitably dehydrated, heated and compressed, woody material becomes thermoplastic and can be moulded. In this form it can compete with ceramic products. Composites with polythene can be extruded into structural elements. In both cases it is abating emissions of the replaced product.
www.google.com/search?q=extruded+wood&es_sm=93&tbm=isch&tbo=u&source=univ&sa=X&ei=JguLU6HRONWcugSuuYK4Cw&ved=0CDMQsAQ&biw=1366&bih=641

Modern biofuels only use the solar energy of its photosynthesis, which is horribly inefficient use of the captured carbon. Given the day of copious non-carbon electricity, vegetable matter of any grade can be upgraded into petrochemical feedstocks, including aviation fuels.

[eclipse]

Jun 1, 2014 21:09:19 GMT 9.5 Roger Clifton said:

May 31, 2014 6:45:07 GMT 9.5 David B. Benson said:

By compressed I mean that the biochar is squeezed hard enough to eliminate all the nanostructure gas passage ways. Then there is no way for micro-organisms to attack it.

Heck, if we're going to heat and compress it to a hard, inert material, why bury it?

Suitably dehydrated, heated and compressed, woody material becomes thermoplastic and can be moulded. In this form it can compete with ceramic products. Composites with polythene can be extruded into structural elements. In both cases it is abating emissions of the replaced product.
www.google.com/search?q=extruded+wood&es_sm=93&tbm=isch&tbo=u&source=univ&sa=X&ei=JguLU6HRONWcugSuuYK4Cw&ved=0CDMQsAQ&biw=1366&bih=641

Modern biofuels only use the solar energy of its photosynthesis, which is horribly inefficient use of the captured carbon. Given the day of copious non-carbon electricity, vegetable matter of any grade can be upgraded into petrochemical feedstocks, including aviation fuels.

I guess the whole point of the biochar cycle is win win win: sequestration, increased soil life and fertility, and some syngas to boot.

[Roger Clifton]

Biochar escapes...

Considering that there are many fire-prone regions around the world, it is something of a puzzle as to why there is not a corresponding amount of pyrogenic carbon in their soils. A recent study, to measure how fast it is eroded away, found instead that biochar is taken away by the groundwater. Presumably it enters the groundwater by dissolution of the oxidation products, or as colloids, potentially including elemental carbon.

[eclipse]

"13,000 years in deep-sea environments (Masiello and Druffel 1998) and was found to have a mean residence time of 10,000 years in soils (Swift 2001)"

[Roger Clifton]

Mar 7, 2016 19:15:24 GMT 9.5 eclipse said:

"(Biochar survives...) 13,000 years in deep-sea environments (Masiello and Druffel 1998) and was found to have a mean residence time of 10,000 years in soils (Swift 2001)"

Please give us links to these papers? We need to know if the "mean" lifetime really is the mean of the population of original deposits. I suspect it is only the average of the samples they were able to collect, a tiny fraction of the original biomass.

[eclipse]

Hmmm, I may have to rethink my biochar page.
www.scientificamerican.com/article/soils-cannot-lock-away-black-carbon/

But what about the Allan Savory & Joel Salatin (famous for Polyface farm) claim that if we changed cattle management to mimic the natural 'mob, mow, and move' strategy in nature, we could bring soils back to life and store all the world's carbon emissions at the same time?


www.youtube.com/watch?v=vpTHi7O66pI

[David B. Benson]

How chocolate could counter climate change
Florian Cazeres
2023 Jun 04
Phys.org
phys.org/news/2023-06-chocolate-counter-climate.html

Boutique solution makes an article on a slow Sunday.  Yawn.

[eclipse]

Biochar might have a bit of a niche, but PF makes it look like a tiny blip. Have I shared this before in another thread?

Soon we’ll be brewing up most of our food in factories. It’s called “Precision Fermentation” and it just needs electricity, water, and a tiny sprinkling of mineral fertilisers. It lets us grow all the fats and proteins we need. Food technicians can form and flavour it into fish-sticks, chicken tenders and bacon strips. The best bit? It could feed 10 billion people from a tiny area the size of greater London! Historically we’ve chopped down 2 billion hectares to graze livestock for very inefficient proteins and fats. It's so inefficient because grass only uses tiny fraction of incoming sunlight, and then livestock eat the grass at a terrible conversion rate to turn it into fats and proteins - all of which wastes an incredible amount of land to generate a tiny amount of protein. PF gets around that by basically using electricity to split water and give the hydrogen directly to fat and protein producing bacteria. It's like beer or bread or cheese, but instead of alcohol or carbs we're brewing up fats and proteins. 

Now, if we can return the 2 billion hectares we graze back to nature, that's enough space for 3 TRILLION trees! Let's regrow that. It would soak up ALL historical CO2 emissions. PF will feed the world abundant cheap food that's safe from flood and drought - and will not cause pandemics like Covid. It will conserve nature, giving forest homes to countless animals. And it would solve climate change. Win win win. "Brave Robot" are already selling PF ice-cream and cream cheese, and others are making palm oil and yoghurt and soon there will be lots of PF milk. Please watch George Monbiot explain more here - just 6 minutes. It's the best technology since renewable energy: youtu.be/6eaTIe_TBZA

[David B. Benson]

Maps reveal biochar’s potential for mitigating climate change
Krishna Ramanujan
2023 Nov 08
Phys.org
phys.org/news/2023-11-reveal-biochar-potential-mitigating-climate.html

Global dataset of crop residues suitable for making biochar