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Post by eclipse on May 25, 2014 19:06:03 GMT 9.5
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.
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Post by Roger Clifton on May 29, 2014 9:12:30 GMT 9.5
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.
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Post by David B. Benson on May 30, 2014 9:06:15 GMT 9.5
Compressed biochar is almost indistinguishable from the highest grade anthracite coal. It'll stay buried as long as buried deep enough.
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Post by Roger Clifton on May 30, 2014 15:46:44 GMT 9.5
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.
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Post by eclipse on May 30, 2014 21:42:17 GMT 9.5
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!? 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.
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Post by David B. Benson on May 31, 2014 6:45:07 GMT 9.5
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.
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Post by eclipse on May 31, 2014 14:36:40 GMT 9.5
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Post by Roger Clifton on May 31, 2014 15:32:35 GMT 9.5
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.htmlwhich 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!
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Post by eclipse on Jun 1, 2014 9:44:17 GMT 9.5
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Post by Roger Clifton on Jun 1, 2014 21:09:19 GMT 9.5
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=641Modern 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.
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Post by eclipse on Jun 2, 2014 20:13:03 GMT 9.5
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=641Modern 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.
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Post by Roger Clifton on Mar 6, 2016 10:03:34 GMT 9.5
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.
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Post by eclipse on Mar 7, 2016 19:15:24 GMT 9.5
"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)"
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Post by Roger Clifton on Mar 10, 2016 8:15:05 GMT 9.5
"(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.
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Post by eclipse on Mar 10, 2016 9:33:11 GMT 9.5
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Post by David B. Benson on Jun 5, 2023 3:41:07 GMT 9.5
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Post by eclipse on Jun 5, 2023 8:17:50 GMT 9.5
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
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Post by David B. Benson on Nov 9, 2023 4:46:53 GMT 9.5
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