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Um... as stated, biomass creation=B'(t)=/=biomass creation. Joel Send a noteboard - 23/10/2011 10:46:04 PM

Render all the carbon dioxide right out of the air into some solid form and dump it on the ground evenly and it would make a layer about about an eighth of an inch high... e.g. a thin layer of mulch.

I think the problem here is that you keep thinking that something that emits it's carbon over a century, instead of months or years, is some sort of 'stopgap', it's not, you need your annual absorption rate to equal your annual increase rate to be carbon neutral, that's the key, and you're thinking of carbon like it was a leaking pipe connected to an effectively infinite reservoir where we can store water in buckets but eventually run out of place to put the buckets and drowned... but it's also not. There is X amount of Fossil Fuels, if we burn them all we must sequester an equal quantity of carbon to keep the atmospheric CO2 levels even, ignoring for the moment that soil and ocean both sequester and release CO2 naturally and that you're standing on more carbon in the first foot of dirt beneath you than the entire atmosphere above you and all that's been in the air before at some point

Assuming that air to dirt interchange is zero and there's some fixed supply of air and fossil fuel and biomass carbon, A, F, and B.... and I'm sorry to keep banging this drum but your last set of comments makes it more clear you're missing this so we'll do equations.

So C = A + B + F; where C is a fixed value,

Pre-industrial: C = A + B and after all fossil fuels are used up this is also true.

Now, we want A to remain constant, therefore B(t) = B-initial + F and to keep a constant B'(t) = F'(t), that is, the rate of biomass increase would have to equal the rate of fossil fuel decrease, or use rate. Obviously this is not the case, were our equation correct, as CO2 ppm has risen.

To sequester this carbon, one must merely make sure at B-final = B initial + F, you are making the incorrect assumption that B'(t) = biomass creation = B(t), effectively the same as assuming miles and miles per hour were the same thing. Two men jogging to New York at the same speed only get to NYC at the same time if they began equidistant, not if one starts in Jersey and the other LA, see? Ultimately B'(t) must equal zero once F is depleted anyway, all that matters is that B-initial + F = B-final so that A final = A initial.

Discrepancy highlighted for convenience; without clarifying that I am not completely certain what you are saying in this section.

Now, just to repeat, while some things like Hemp happening to suck down carbon very quickly and cheaply, which is good, a field of Hemp might be an inferior sequestering source compared to pine, if its overall turnover rate meant that at any given time the Hemp acre had 50 tons of Carbon locked up and the Pine Acre had 100 tons, even if the pine grows slower. A Strawberry field has a fairly decent absorption rate for instance, but virtually no turnover time and might stores only a few tons per acre, making it very bad for this purpose, however that same field, if it were, say, mulched with tree bark that had to be replenished at a rate of 10% a year, might have a couple pounds of mulch per foot on it at all times, or about 50 tons an acre, suddenly making it a fairly decent sequestering point and cheaper to irrigate and potentially making a faster growing mulch source that natively stored less carbon than, say, redwoods, an appealing sequester method. The rate of absorption, while an important factor, is essentially secondary, it is the tonnage per acre that interests us. To place this in perspective, this planet has some 32 billion acres of land, to sequester 320 GT of CO2 on that would require 10 tons of additional material per acre, but would not require those acres grow faster, merely that the material on them be more massive. If, to pull some number out of my rear, an acre of pine, suddenly ripped out root and stump, weighed 50 tons of carbon, and was replaced with an acre of oak, fully grown at 60 tons, this would result in a net permanent reduction of 10 tons for that acre, even if the oak took twice as long to grow, similarly knocking down that pine and replacing it with potatoes, at say 40 tons of stored carbon on average per acre, would result in an atmosphere increase of 10 tons of carbon, but is basically yanking 40 tons of carbon out of the air each year compared to much lower amounts from those tree type [these are all made up numbers] making it an inferior crop for sequestering... however if it were used in tandem with an acre of the faster growing pine, where old pines were mulched down to make room for new pines at a rate of say 31 tons of pine mulch a year, suddenly the pine and potato acres would be at 121 tons of sequestering per two acres, or 60.5 tons, exceeding the Oak acre, and serving as a superior sequestering depot... because at any given time they'd have more carbon stored. There release rate doesn't matter any more than a chunk of limestone's does, the stuff isn't in the air.

"Permanent" is a big word. Short of sealing carbon off in an impenetrable hole (which, again, I do not advocate) it cannot be permanently removed from the atmosphere. It cannot be even temporarily removed unless the amount converted to biomass exceeds the combination of what decaying biomass and burning fossil fuels release. The time scale in itself matters no more than the form of biomass: The amount of atmospheric CO2 CANNOT be as low as pre-industrial levels unless the amount of biomass at ANY GIVEN TIME equals the pre-industrial level plus the amount needed to store all carbon released by burning fossil fuels.

That could take the form of biofuel, grain or redwoods (indeed, the last two are ultimately just forms of the first, though lumber has other uses,) but any of them would eventually die, decay and elevate atmospheric CO2 to its former levels unless replaced by an equal biomass. The only relevance long term carbon sinks have is allowing more time to develop those replacements. Theoretically, we could cycle CO2 through massive seeding projects indefinitely, but the rate at which those projects must proceed is directly proportional to the persistence of the resulting carbon sinks: If the sinks last six months we must constantly plant at a break neck pace, whereas new forests that would last a century or two would allow a more relaxed pace (except perhaps during the first round.)

So I guess it is not fair to say sequestration is a fools errand, but it would take at least twice as much area as simply creating a sink for atmospheric CO2, because however great that value is, an equal value would be necessary for when the biomass occupying it has ceased removing CO2 from the atmosphere and begun reintroducing it. There is certainly a finite amount of carbon that can enter the atmosphere as CO2; most terrestrial carbon never will (or will only do so on geologic time scales, which is practically the same for our purposes and not something we can easily control regardless.) However, unless we truly DUMP rather than merely sinking it, that finite amount, whatever it is, can never leave that atmosphere without somewhere to go, and any place we put it as biomass is a temporary solution that must be complemented by an additional sink when it inevitably begins releasing the carbon it previously stored.

Again, with the amount of terrestrial forestation falling rather than climbing that becomes a very significant obstacle to carbon sequestration as a practical solution. Sequestration requires increasing biomass by an amount equal to the increase in atmospheric CO2 since the Industrial Revolution AND SUBSEQUENTLY by an amount equal to that biomass before it releases its carbon again. As long as we continue reducing our vegetative biomass we cannot even begin the first part of that task, let alone the second, and doing the first without the second only delays rather than solves the problem. Simultaneously increasing the rate at which we clear forests AND burn fossil fuels was undeniably a double whammy that spiked atmospheric CO2, and anyone who thinks that has not increased Earths surface temperature is living in denial, but expecting to solve the problem by farming the Sahara is equally unrealistic. First and foremost, if that were an option we would not have been clearing forests for agricultural land in the first place, but, as I hope I have demonstrated, it would require planting an area 2/3 the size of Libya rather than 1/3 even if that option became viable tomorrow.

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Interesting new Biofuel innovation: Magnetic Algae Isaac - 22/10/2011 03:05:13 AM 493 Views

I must be missing something with biofuel, though this certainly sounds like good news for it. Joel - 22/10/2011 04:41:17 AM 265 Views

It's rather difficult to cram a fission reactor into a car

Isaac - 22/10/2011 05:10:23 AM 269 Views

If the batteries are that bulky then, yeah, biomass or something similar is appealing. Joel - 22/10/2011 07:15:22 AM 345 Views

We're constrained by what economics and tech permit Isaac - 22/10/2011 08:09:22 AM 266 Views

And physics, always physics. Joel - 22/10/2011 08:34:07 AM 310 Views

And scale... scale is important too

Isaac - 22/10/2011 01:40:18 PM 249 Views

True, but sequestrations bottom line is we have to remove more than is released from biomass. Joel - 23/10/2011 11:41:20 AM 366 Views

I think you're still misunderstanding this concept Isaac - 23/10/2011 01:26:14 PM 247 Views

Um... as stated, biomass creation=B'(t)=/=biomass creation. Joel - 23/10/2011 10:46:04 PM 385 Views

No, that would be net Biomass increase with time Isaac - 24/10/2011 07:49:10 AM 253 Views

But is not "net biomass increase with time" the same as "biomass creation"? Joel - 25/10/2011 02:54:16 AM 414 Views

Forget Biofuel. When do we start making magnetic people! Dannymac - 22/10/2011 07:43:43 AM 229 Views

One would have problems imagining why

Isaac - 22/10/2011 08:09:55 AM 250 Views

Except during the middle of the day, you can usually use the sun. Joel - 22/10/2011 08:36:54 AM 259 Views

Uh... have you ever tried to navigate by the sun? Ghavrel - 22/10/2011 09:05:40 PM 240 Views

Frequently, hence the comment. Joel - 23/10/2011 09:35:31 AM 322 Views

"Why"?! So I could be a Mistborn. "Why" is the least-relevant question. *NM* Gher - 22/10/2011 07:56:16 PM 135 Views

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<quote id="231836">
<quote id="231806">Render all the carbon dioxide right out of the air into some solid form and dump it on the ground evenly and it would make a layer about about an eighth of an inch high... e.g. a thin layer of mulch.

I think the problem here is that you keep thinking that something that emits it's carbon over a century, instead of months or years, is some sort of 'stopgap', it's not, you need your annual absorption rate to equal your annual increase rate to be carbon neutral, that's the key, and you're thinking of carbon like it was a leaking pipe connected to an effectively infinite reservoir where we can store water in buckets but eventually run out of place to put the buckets and drowned... but it's also not. There is X amount of Fossil Fuels, if we burn them all we must sequester an equal quantity of carbon to keep the atmospheric CO2 levels even, ignoring for the moment that soil and ocean both sequester and release CO2 naturally and that you're standing on more carbon in the first foot of dirt beneath you than the entire atmosphere above you and all that's been in the air before at some point :P Assuming that air to dirt interchange is zero and there's some fixed supply of air and fossil fuel and biomass carbon, A, F, and B.... and I'm sorry to keep banging this drum but your last set of comments makes it more clear you're missing this so we'll do equations.

So C = A + B + F; where C is a fixed value,

Pre-industrial: C = A + B and after all fossil fuels are used up this is also true.

Now, we want A to remain constant, therefore B(t) = B-initial + F and to keep a constant B'(t) = F'(t), that is, the rate of biomass increase would have to equal the rate of fossil fuel decrease, or use rate. Obviously this is not the case, were our equation correct, as CO2 ppm has risen.

To sequester this carbon, one must merely make sure at B-final = B initial + F, you are making the incorrect assumption that B'(t) = biomass creation = B(t), effectively the same as assuming miles and miles per hour were the same thing. Two men jogging to New York at the same speed only get to NYC at the same time if they began equidistant, not if one starts in Jersey and the other LA, see? Ultimately B'(t) must equal zero once F is depleted anyway, all that matters is that B-initial + F = B-final so that A final = A initial.</quote>
Discrepancy highlighted for convenience; without clarifying that I am not completely certain what you are saying in this section.

<quote id="231806">Now, just to repeat, while some things like Hemp happening to suck down carbon very quickly and cheaply, which is good, a field of Hemp might be an inferior sequestering source compared to pine, if its overall turnover rate meant that at any given time the Hemp acre had 50 tons of Carbon locked up and the Pine Acre had 100 tons, even if the pine grows slower. A Strawberry field has a fairly decent absorption rate for instance, but virtually no turnover time and might stores only a few tons per acre, making it very bad for this purpose, however that same field, if it were, say, mulched with tree bark that had to be replenished at a rate of 10% a year, might have a couple pounds of mulch per foot on it at all times, or about 50 tons an acre, suddenly making it a fairly decent sequestering point and cheaper to irrigate and potentially making a faster growing mulch source that natively stored less carbon than, say, redwoods, an appealing sequester method. The rate of absorption, while an important factor, is essentially secondary, it is the tonnage per acre that interests us. To place this in perspective, this planet has some 32 billion acres of land, to sequester 320 GT of CO2 on that would require 10 tons of additional material per acre, but would not require those acres grow faster, merely that the material on them be more massive. If, to pull some number out of my rear, an acre of pine, suddenly ripped out root and stump, weighed 50 tons of carbon, and was replaced with an acre of oak, fully grown at 60 tons, this would result in a net permanent reduction of 10 tons for that acre, even if the oak took twice as long to grow, similarly knocking down that pine and replacing it with potatoes, at say 40 tons of stored carbon on average per acre, would result in an atmosphere increase of 10 tons of carbon, but is basically yanking 40 tons of carbon out of the air each year compared to much lower amounts from those tree type [these are all made up numbers] making it an inferior crop for sequestering... however if it were used in tandem with an acre of the faster growing pine, where old pines were mulched down to make room for new pines at a rate of say 31 tons of pine mulch a year, suddenly the pine and potato acres would be at 121 tons of sequestering per two acres, or 60.5 tons, exceeding the Oak acre, and serving as a superior sequestering depot... because at any given time they'd have more carbon stored. There release rate doesn't matter any more than a chunk of limestone's does, the stuff isn't in the air.</quote>
"Permanent" is a big word. Short of sealing carbon off in an impenetrable hole (which, again, I do not advocate) it cannot be permanently removed from the atmosphere. It cannot be even temporarily removed unless the amount converted to biomass exceeds the combination of what decaying biomass and burning fossil fuels release. The time scale in itself matters no more than the form of biomass: The amount of atmospheric CO2 CANNOT be as low as pre-industrial levels unless the amount of biomass at ANY GIVEN TIME equals the pre-industrial level plus the amount needed to store all carbon released by burning fossil fuels.

That could take the form of biofuel, grain or redwoods (indeed, the last two are ultimately just forms of the first, though lumber has other uses,) but any of them would eventually die, decay and elevate atmospheric CO2 to its former levels unless replaced by an equal biomass.  The only relevance long term carbon sinks have is allowing more time to develop those replacements.  Theoretically, we could cycle CO2 through massive seeding projects indefinitely, but the rate at which those projects must proceed is directly proportional to the persistence of the resulting carbon sinks:  If the sinks last six months we must constantly plant at a break neck pace, whereas new forests that would last a century or two would allow a more relaxed pace (except perhaps during the first round.)

So I guess it is not fair to say sequestration is a fools errand, but it would take at least twice as much area as simply creating a sink for atmospheric CO2, because however great that value is, an equal value would be necessary for when the biomass occupying it has ceased removing CO2 from the atmosphere and begun reintroducing it.  There is certainly a finite amount of carbon that can enter the atmosphere as CO2; most terrestrial carbon never will (or will only do so on geologic time scales, which is practically the same for our purposes and not something we can easily control regardless.)  However, unless we truly DUMP rather than merely sinking it, that finite amount, whatever it is, can never leave that atmosphere without somewhere to go, and any place we put it as biomass is a temporary solution that must be complemented by an additional sink when it inevitably begins releasing the carbon it previously stored.

Again, with the amount of terrestrial forestation falling rather than climbing that becomes a very significant obstacle to carbon sequestration as a practical solution. Sequestration requires increasing biomass by an amount equal to the increase in atmospheric CO2 since the Industrial Revolution AND SUBSEQUENTLY by an amount equal to that biomass before it releases its carbon again. As long as we continue reducing our vegetative biomass we cannot even begin the first part of that task, let alone the second, and doing the first without the second only delays rather than solves the problem. Simultaneously increasing the rate at which we clear forests AND burn fossil fuels was undeniably a double whammy that spiked atmospheric CO2, and anyone who thinks that has not increased Earths surface temperature is living in denial, but expecting to solve the problem by farming the Sahara is equally unrealistic. First and foremost, if that were an option we would not have been clearing forests for agricultural land in the first place, but, as I hope I have demonstrated, it would require planting an area 2/3 the size of Libya rather than 1/3 even if that option became viable tomorrow.
</quote>

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