nding Global Warming via Biocoal Sequestration
David B. Benson
Hansen et al., March 2008,"Target CO2: Where Should Humanity
Aim?" found here:
http://www.columbia.edu/%7Ejeh1/
states that we need to soon reduce atmospheric CO2 from the
current 385 ppm to an initial 350 ppm for compelling reasons.
Here is an outline of a plan for doing so.
The world economy is about 67 trillion dollars (GDP).
Imposing a VAT of 1% raises then 670 billion dollars per year.
This sum is used to grow biomass, convert it to biocoal, and
sequester the biocoal in carbon landfills, every year until
the goal of 350 ppm is met.
Using Powder River Basin style earth movement, it would cost
about $16.50 per tonne to sequester the biocoal. In addition,
the biomass must be harvested, moved to the hydrothermal
carbonization facility, converted to biocoal (while generating
some process heat for electricity generation), and then the
biocoal moved to the landfill site. By conducting all these
operations in parts of the world with ample excess land and
low-cost labor (Africa) I will assume these steps can be done
for only $33.50 per tonne, under half the amount required in
the developed world. Thus the carbon capture and
sequestration net costs are assumed to be $50 per tonne of
biocoal.
I will assume, for simplicity, that the biocoal is 85% carbon.
Humans are currently adding about 8.5 gigatonnes of carbon
(GtC) to the active carbon cycle per year, mostly by burning
fossil carbon. Just to maintain the current 385 ppm of
atmospheric CO2 then requires producing and sequestering
10 gigatonnes of biocoal per year. This costs $500 billion
per year, leaving a net of $170 billion available for
producing and sequestering additional biocoal to reduce the
concentration of CO2 in the atmosphere.
To reduce the concentration to 350 ppm requires removing
about 185 GtC from the active carbon cycle. At the rate
of ian additional 3.4 gigatonnes of biocoal per year, using
the net funds available, we would remove 2.89 GtC from the
active carbon cycle each year. Assuming this is done at
a steady rate, it will require 64 years to bring about the
desired initial atmospheric CO2 concentration of 350 ppm.
About Biocoal
Popular accounts:
http://www-dw.world.de/dw/article/0,2144,2071791,00.html
http://biopact.com/3007/05/scientists-describe-hydrothermal.html
A demonstration plant is described in the following link.
http://biopact.com/2007/08/belgian-dutch-partnership-to-develop.html
Technical article:
M.-M. Titrisci, et al.,
Back in the Black: hydrothermal carbonization of plant
material as an effiecient chemiccal process to treat the CO_2
problem?
New Journal of Chemistry, 207, 31, 787--798 (25 references). (Linked
below)
http://www.rsc.org/delivery/_ArticleLinking/DisplayHTMLArticleForFree.cfm?JournalCode=NJ&Year=2007&ManuscriptID=b616045j&Iss=6
or as a .pdf file
http://www.rsc.org/Publishing/Journals/NJ/article.asp?doi=b616045j
James Annan
>
> I will assume, for simplicity, that the biocoal is 85% carbon.
> Humans are currently adding about 8.5 gigatonnes of carbon
> (GtC) to the active carbon cycle per year, mostly by burning
> fossil carbon. Just to maintain the current 385 ppm of
> atmospheric CO2 then requires producing and sequestering
> 10 gigatonnes of biocoal per year.
It's not as bad as that, actually. A large chunk of what we are
currently producing is being soaked up by oceans and biomass. So we
only need to sequester about half of gross emissions to stabilise
atmospheric CO2, and anything more will cause a decline. Of course
this sink will not last for ever (the ocean will saturate) but it
does reduce the scale and urgency of the issue (setting aside for now
whether this sort of target is sensible in the first place).
James
David B. Benson
On Mar 18, 10:12 pm, "James Annan" <james.an...@gmail.com> wrote
...
> currently producing is being soaked up by oceans and biomass. So we
> only need to sequester about half of gross emissions to stabilise
>
> James
Thanks. I ignored this point under the assumption that as the decline
begins, the ocean, land and biomass will all give up some of the
excess CO2 to maintain equilibrium. Of course, water with excess CO2
which descends into the deep ocean won't be seen for quite a long
time, but I have assumed (this may be long) that very little has gone
deep yet.
Michael Tobis
suggetsion) I don't expect that concentrations would stabilize.
The details are complicated, but as I understand it, to first order an
excess unit of CO2 on decadal time scales has a 50% chance of ending
up in the biota or the ocean. That is, the biota and the ocean are
equilibrating to the excess, not to the amount. Accordingly David's
approximation seems much better to me than James' does. (Such drawdown
as exists is on millenial time scales and is thus of second order on
the time scale of interest here.)
David, am I reading correctly that you are proposing sequestering the
biocoal directly? Why not burn it and sequester the CO2 instead?
Also, you get a third of your cost back because you are replacing coal
which is not free.
mt
David B. Benson
> ...
> biocoal directly? Why not burn it and sequester the CO2 instead?
Many variations are possible. This sketch-of-a-plan has the advantage
of not only being easy to explain, but surely providing safe, secure,
permanent sequestration. Sequestering CO2 does not offer that high
assurance at this time.
The price of coal is now high enough (see Wednesday's TNYT) that
investors ought to be seriously considering making biocoal to compete
in the metalugical anthracite market. Looks to me there is money to
be made, in a carbon-neutral fashion.
jdannan
> The price of coal is now high enough (see Wednesday's TNYT) that
> investors ought to be seriously considering making biocoal to compete
> in the metalugical anthracite market. Looks to me there is money to
> be made, in a carbon-neutral fashion.
There was an interesting article in NewScientist a few months ago,
suggesting that "peak coal" may also be upon us rather earlier than many
official estimates (and for similar reasons).
"THERE used to be a saying about taking coal to Newcastle, but these
days the issue is getting the stuff out. Newcastle in New South Wales,
Australia, may be the biggest coal export terminal in the world's
biggest coal-exporting country, but even it is having trouble keeping up
with demand. The line of ships waiting to load coal can stretch almost
to Sydney, 150 kilometres to the south. At its peak last year, there
were 80 vessels in the queue, each forced to lie idle for up to a month.
"The delays have been increasing since 2003, and not just because of the
port's limited capacity. Gnawing doubts are also beginning to emerge
about the supply of coal, not just in Australia but worldwide, and not
only because of logistics but also because of geology. In short, coal
may be running out."
James
Don Libby
Newsgroups: gmane.science.general.global-change
To: "globalchange" <global...@googlegroups.com>
Sent: Tuesday, March 18, 2008 5:08 PM
Subject: [Global Change: 2477] nding Global Warming via Biocoal
Sequestration
>
> the biomass must be harvested, moved to the hydrothermal
> carbonization facility, converted to biocoal (while generating
> some process heat for electricity generation), and then the
> biocoal moved to the landfill site. By conducting all these
> operations in parts of the world with ample excess land and
> low-cost labor (Africa) I will assume these steps can be done
Two potential flies gathering around the ointment: land management and labor
management.
The price of charcoal in Africa is skyrocketing due in part to supply
restrictions brought about by bans on traditional charcoal producers'
deforestation practices. The charcoal market is sending a clear signal:
Africa needs to produce more charcoal (or a cheaper, more suitable
substitute). But sustainable forestry policy demands that this be done as
efficiently as possible, with attention to reforestation and biodiversity
preservation.
Building a modern capital-intensive mechanized biocoal industry in the
tropics (e.g. a Million Herreshoff Furnaces) will be challenging, and not
least of the challenges will be social equity concerns for workers displaced
from the traditional charcoal industry by mass production of low-cost
biocoal. With livelihoods at stake, there is potential for social conflict
if the benefits of industrialization are not shared fairly. The history of
industrialization in the developed world has taught us that there should be
equal power-sharing between the interests of capital and labor, which
requires establishing respect for the rule of law to avoid open conflict.
The history of industrialization in the developing world has taught us this
is not always so.
This brings us to fly number two: slavery in charcoal camps. Charcoal is
used extensively to produce pig iron in Brazil, and slavery has been
documented. Respect for human rights and the rule of law are sometimes
lacking in tropical forests where industrial production under conditions of
extreme poverty is concerned. It is a challenge to ensure that the biofuels
and carbon offset industries play by the rules in developing countries. We
should move forward to meet that challenge in the tropics, and also consider
the potential to grow these industries in temperate climates, where the
regulatory framework for socially just and ecologically sustainable
industrial forestry is better established. If the agribusiness marketing
machine can be turned on to Agrichar, then we may begin burying charcoal on
a large scale, at a profit.
African charcoal market:
http://www.sundayvision.co.ug/detail.phpmainNewsCategoryId=7&newsCategoryId=132&newsId=616830
Slavery in charcoal camps:
http://www.bloomberg.com/news/marketsmag/modern_slavery1.html
Agrichar:
http://www.abc.net.au/catalyst/stories/s2012892.htm
-dl
Don Libby
Newsgroups: gmane.science.general.global-change
To: <global...@googlegroups.com>
Sent: Sunday, March 23, 2008 5:22 AM
Subject: [Global Change: 2483] Re: nding Global Warming via Biocoal
Sequestration
>
> African charcoal market:
> http://www.sundayvision.co.ug/detail.phpmainNewsCategoryId=7&newsCategoryId=132&newsId=616830
>
That link is bad, try this one instead: http://tinyurl.com/2k8647
-dl
David B. Benson
First, biocoal is made via hyrothermal carbonization, basically a
pressure cooker. So no Herreshoff Furnaces are used.
Second, I certainly agree that sound, healthy practices are required.
Third, there is an abundance of suitable, non-arible, unforested land
elsewhere in Africa than in the tropics. The entire Sahel, most of
Madagascar, most of Nambia, etc.
Don Libby
Sent: Sunday, March 23, 2008 1:32 PM
Subject: [Global Change: 2485] Re: nding Global Warming via Biocoal
Sequestration
>
> Don Libby:
>
> First, biocoal is made via hyrothermal carbonization, basically a
> pressure cooker. So no Herreshoff Furnaces are used.
>
It's not clear to me what advantage biocoal batch production via pressurized
hydrothermal carbonization would have over continuous char production via
fast or slow pyrolysis for the purpose of landfilling or soil amendment.
For example, here is a company with a continuous fast pyrolysis process
developed to the point of early commercialization, which produces char as
well as liquid and gaseous fuels from a variety of feedstocks:
http://www.dynamotive.com/ .
It would seem to me that char produced by pyrolysis in Ontario would serve
the carbon sequestration purpose at least as well as biocoal produced by
hydrothermal carbonization in Namibia, no?
Thanks,
-dl
David B. Benson
> ...
> the carbon sequestration purpose at least as well as biocoal produced by
> hydrothermal carbonization in Namibia, no?
>
will stay unchanged in the ground for millions of years. That
may not be true of biochar. It certainly is not when applied
as a soil amendment. See this survey report:
http://terrapreta.bioenergylists.org/node/578
The other problem is cost, primarily that of collecting the
biomass and transporting it to the reactor (which might be
hydrothermal carbonization, torrifaction, or pyrolysis). The
costs in Africa will be substantially less than in Ontario.
Do note that in my original post starting this thread, I
provided several links regarding biocoal. One is to an
article about a demonstation plant in The Netherlands which
produces 75,000 tonnes per year. It doesn't appear that batch
versus continuos is an issue.
hgerh...@yahoo.co.uk
> will stay unchanged in the ground for millions of years. That
> may not be true of biochar.
includes my own institutiton, namely the Energy Research Centre of the
Netherlands#.
http://www.ecn.nl/publications/default.aspx?nr=c05013
You will find much more by googling "ECN torrefaction".
The article you quote:
http://biopact.com/2007/08/belgian-dutch-partnership-to-develop.html
is a cut and paste job by an overworked editor. Look at the graphic:
http://i169.photobucket.com/albums/u238/biopact2/biopact_biocoal_comparison.jpg?t=1186749895
It has zero scientific content and comes from this website:
http://www.biocoal.net/comparison.html
The Biopact story basically fuses two stories that have nothing to do
with each other, and then throws in some further information gleaned
from a very dubious website, the sole connection being the use of the
term "biocoal".
> It certainly is not when applied
> as a soil amendment. See this survey report:
>
> http://terrapreta.bioenergylists.org/node/578
there are differences in biodegradability between different kinds of
coal, lignite, peat, torrefied biomass etc.., but I don't think they
are well researched, and I suspect that coal may be safe from aerobic
degradation for millions of years because it is in an anaerobic
environment.
Does anybody here know of research looking at the potential albedo
effects of using carbon as a soil conditioner?
# The usual disclaimer, this is my own private opinion and I am not
speaking for my own employer in this forum.
David B. Benson
On Mar 26, 12:30 pm, "hgerhau...@yahoo.co.uk" <hgerhau...@yahoo.co.uk>
wrote:
> ...
And used to refer to different materials. The original use of the
term 'biocoal' was for the material produced by hydrothermal
carbonization. In my oopinion it should not be used for torrified
wood.
Your comment regarding aneorbic environments may well be correct, but
the prior treatment of the biomass clearly makes a difference as well
in that very old, deeply buried charcoal is rarely found. (I know of
no such from the geologic literature; only some in soils and still
young enough to approximately carbon radiodate.)
My original point was that we can begin now to bury the excess carbon
using a method known to be permanent. The technology exists (even if
you didn't care for my link to the story about the demonstration
plant.) All that is lacking is the will.
Michael Tobis
mt
David B. Benson
> Wouldn't the best way to end up with a given amount of buried coal be ...
Yup. But it is a done deal, about 500 GtC worth. Much of that needs
putting back, one way or the other.
That said, if biocoal can be produced as inexpensively as I estimated,
provided the locations are not stranded (that is, transportation costs
are too high), biocoal could compete with coal in today's market
place.
Indeed, the cost of metalurgical grade anthracite (coking coal) is now
so high that I am quite convinced that bio-anthracite can readily find
a market. It just takes somebody to start doing it.
But the point was that for quite a modest tax, it would be possible to
start 'putting it back' today, safely and 'forever' secure.
hgerh...@yahoo.co.uk
> using a method known to be permanent. The technology exists (even if
> you didn't care for my link to the story about the demonstration
> plant.) All that is lacking is the will.
working in the field. People have been pressure cooking biomass in all
sorts of variants for ages. The Max Plank institute is relatively new
to this and I do not think they have found anything particularly novel
or exciting. Nor are they about to commercialise their process in
Coevorden, that plant has nothing to do with their lab scale
dabbling.
Nor do I see any evidence that this particular pressure cooking
variant would make biomasss especially resistant to biodegradation
compared to other carbonisation methods, or any reason why they the
term biocoal should suddenly be restricted to their product, when it
was used by others long before they got into this business.
Not to say that there aren't differences in biodegradation behaviour,
but you can't just point to a distinction between "charcoal" and
"coal", say the former is degraded over time and the latter isn't, and
then losely associate a particular carbonisation method with "coal"
and another (all others???) with "charcoal" and declare that therefore
one carbonisation method is superior to the other. That logic doesn't
work.
hgerh...@yahoo.co.uk
> refrain from digging that amount up in the first place?
might wish to dig up coal and simultaenously bury some carbon of
recent biogenic origin. High ash content with the wrong ash elements
causing boiler fouling would come to mind, especially if the ash
elements that are most difficult in combustion equipment are good for
fertilisers (eg potassium).
We are then talking high cost, low efficiency for the combustion of
charcoal, and additional benefits beyond carbon sequestration for
burying the charcoal.
If you then ask, given a certain quantity of charcoal, whether it's
better to burn it instead of coal or bury it, you might find that the
charcoal sells for more as a soil conditioner / fertiliser than as a
fuel, and that burying it also keeps more carbon out of the air than
burning it in inefficient dedicated plants that displace very
efficient coal fired generation.
Whether it actually makes sense of course depends on how valuable as a
soil conditioner/fertiliser charcoal really is, and how serious the
problems are when combusting it. Personally, I think the soil
conditioner benefits of charcoal are oversold by advocates of burial,
and the combustion issues are manageable. Note that I am biased in
this particular dogfight, because I am currently employed to do
research on biocoal, that is torrefaction of biomass, with the near
term market being co-firing with coal.
David B. Benson
wrote:
> ...
> or exciting. Nor are they about to commercialise their process in
> Coevorden, that plant has nothing to do with their lab scale
> dabbling.
> Nor do I see any evidence that this particular pressure cooking
> variant would make biomasss especially resistant to biodegradation
> compared to other carbonisation methods, or any reason why they the
> term biocoal should suddenly be restricted to their product, when it
> was used by others long before they got into this business.
pressure cooking method is that it is possible to produce anthracite.
Surely this is not possible via pyrolysis or torrifaction? Not even
bitumin?
> Not to say that there aren't differences in biodegradation behaviour,
> but you can't just point to a distinction between "charcoal" and
> "coal", say the former is degraded over time and the latter isn't, and
> then losely associate a particular carbonisation method with "coal"
> and another (all others???) with "charcoal" and declare that therefore
> one carbonisation method is superior to the other. That logic doesn't
> work.
ground while naturally produced charcoal appears (so far) to last for
only thousands, sometimes a few tens of thousands of years. Of
course, torrifaction does not naturally occur (in any quantity) so
there is no data.
Since hydrothermal carbonization was done specifically to produce
actual coal, very much faster than nature does it, it appears to be
the most secure way to produce a carbonaceous material for permanent
burial of carbon. I doubt that it is more expensive to produce in
quantity than biochar or torrified wood. In principle any source of
biomass could be used. [The process is rather similar to hydrothermal
liquification. There is a demonstration plant in The Netherlands
(Amsterdam, I think) which uses municiple waste water (clarification
sludge) to produce high-quality biodiesel via hydrothermal
liquification.]
With regard to natural coal persisting due to an anerobic environment,
I now do not think that is a requirement. I know of a site with
anthracite only a few centimeters under the soil. Paleoamericans used
the anthracite for heat, leading to a very wrong radiocarbon date!
Regarding using biochar as a soil amendment, all the trials to date
suggest this is a winner. Except if the goal is long-term storage of
the carbon in the ground. Actual field experince shows that about
half returns to the active carbon cycle after a few years. The other
half persists for lengths of time which may depend upon the soil type,
etc. The Amazoniam Terra Preta soils appear to provide carbon dates
of up to 7000 years, but the other data is all from naturally occuring
charcoal. That data suggests to me that soil type may well play an
important role. In any case, I know of no reports in the geological
literature of any naturally occuring charcoal in srata more than a few
tens of thousands of years old.
Despite our differences of opinion, I greatly appreciate your informed
comments on this thread.
hgerh...@yahoo.co.uk
> pressure cooking method is that it is possible to produce anthracite.
> Surely this is not possible via pyrolysis or torrifaction? Not even
> bitumin?
you'll get a solid product that is richer in C and poorer in O. That
can nicely be plotted on the van Krevelen diagram, eg (see slide 6 of
10) and results in the same trend as for peat/bituminous coal/
anthracite:
http://www.thermalnet.co.uk/docs/ECN_%20Torrefaction%20of%20Biomass%20as%20pretreatmentLille.pdf
As for their product being exactly like coal otherwise, they say:
http://www.mpg.de/english//illustrationsDocumentation/multimedia/mpResearch/2007/heft/pdf23.pdf
"The product is brown or black, feels exactly
like coal and has the same calorific value and
many of the same chemical properties as fossilized
coal. There are, however, some characteristic differences.
For example, the nature of the carbon
bonds is more aliphatic and there are only a few
aromatic moieties. Furthermore, vegetable carbon
is more chemically reactive and has an open,
porous structure. ...
If the bound carbon were to be considered
for use as a means of improving the soil in the
natural environment, the lack of biodegradability
is obviously something that would need to be
quantified."
> I doubt that it is more expensive to produce in
> quantity than biochar or torrified wood.
more expensive it gets, and the less energy remains in the solid
product.
ECN don't just do torrefaction (heating to around 250C in the absence
of oxygen), but also something called torwash (heating to around 200C
in water under pressure). The latter is clearly more costly (due to
the requirement for pressure vessels) and is intended for difficult
feedstocks with a lot of ash and plenty of moisture to start off with.
Residence time has a very direct impact on cost, having to heat
something for 12 hours rather than 12 minutes means the same equipment
will handle 60 times less material (or respectively you need to build
something 60 times as big to handle the same throughput of biomass)!
For cheap equipment that's not a problem, but for pressure vessels
that need to be built to stand a potential thermal runaway and
consequent explosion ...
> With regard to natural coal persisting due to an anerobic environment,
> I now do not think that is a requirement. I know of a site with
> anthracite only a few centimeters under the soil. Paleoamericans used
> the anthracite for heat, leading to a very wrong radiocarbon date!
and the like) is more biodegradable than anthracite. I must say that
I've only got educated guesses for the issue of very long term
biodegradability in soils. For torrefied biomass we are interested in
whether it'll biodegrade when stored outside in large heaps for a few
months or years and that sort of thing. This is a very different
question from intimate soil contact for thousands of years. I would
guess that fine distribution might matter, because bacteria living in
anthracite might have to live from anthracite alone, while a bit of
charcoal in soil would allow bacteria to crunch on the carbon as a
little extra.
Don Libby
Newsgroups: gmane.science.general.global-change
To: "globalchange" <global...@googlegroups.com>
Subject: [Global Change: 2514] Re: nding Global Warming via Biocoal
Sequestration
>
> On Mar 31, 4:58 pm, "Michael Tobis" <mto...@gmail.com> wrote:
>> Wouldn't the best way to end up with a given amount of buried coal be to
>>refrain from digging that amount up in the first place?
>
> Yup. But it is a done deal, about 500 GtC worth. Much of that needs
> putting back, one way or the other.
<...>
> But the point was that for quite a modest tax, it would be possible to
> start 'putting it back' today, safely and 'forever' secure.
Diamonds are forever. I suppose graphite is too, for present purposes.
Both can be synthesized, for a price: is it worth it? Pressure-cooked
bio-anthracite may be stable enough, indeed ordinary charcoal may be stable
enough, but further research is required to measure biodegradability. Seems
like a good idea. I suspect the excellent article you posted
(http://orgprints.org/13268/01/Biochar_as_a_soil_amendment_-_a_review.pdf),
or something very similar will find its way into the next IPCC assessment
report on "mitigation strategies". Certainly worth a closer look, but the
closer I look at the ointment I see a multiplying myriad of flies.
On economic grounds, one estimate says torrefied wood transported 80 miles
or less is competitive with coal at $80/ton for electricity production in
South Carolina (
http://terrapreta.bioenergylists.org/files/TorrefiedWoodPresentation_2-08.pdf )
. Central Appalachian coal is currently selling at about that price (Powder
River Basin coal goes for about $15/ton). Annual torrefied wood production
from logging slash would amount to 10% of annual coal use for South
Carolina. This suggests that even with the biofuel carbon offset, the coal
plants should be fitted with carbon capture and storage technology if a
radical reduction in carbon emissions is desired.
That analysis assumes that forestry slash can be utilized for torrefaction,
which is by no means certain. Looking at biomass removal as an alternative
to prescribed burns in US forests, no less than 34 technical, economic,
environmental, and socio-political barriers have been identified (
http://www.wrapair.org/forums/fejf/documents/task4/WRAP_Non-Burning.ZIP).
In Wisconsin, with abundant forestry residues, two wood-burning electric
power plants (Xcel Energy 100 MW units at French Island and Bay Front), and
greater demand than available supply of waste-wood, market research has
shown fuel-wood plantations to be more viable than forest residue harvest.
Woody biomass energy plantations compete for land with food crops, and have
a long investment recovery period: there are no woody biomass energy
plantations in Wisconsin despite favorable conditions (
http://www.rs-inc.com/downloads/FOE%20Bioenergy%20Final%20Report_091707.pdf
).
In February 2008 the NRC docketed Duke Energy's application to build two
AP1000 power plants at the site of the existing Lee nuclear generating
station in South Carolina, which amounts to about 33% of existing coal-fired
generating capacity in that state. Doubling that state's nuclear capacity
would eliminate coal from its generating mix - probably the most direct path
toward "leaving coal in the ground", rather than fussing around in the
forest. Doubling nuclear capacity would leave many smaller gas and
oil-fired plants to experiment with carbon capture and storage along with
bio-gas and bio-oil combustion, and would leave bio-char to be marketed
primarily for soil improvement rather than energy production. If carbon
emission taxes (or caps) and tradable carbon offset/sequestration credits
can be secured by bio-char/gas/oil (and nuclear power) producers, so much
the better for a "carbon negative" energy mix.
-dl
hgerh...@yahoo.co.uk
> a long investment recovery period
generation biofuels. Currently we produce substantially more food than
we actually need, due to large meat consumption, food overconsumption
and indeed (though so far still to a much lesser extent) biofuels. I
see two huge positives about that, that way we've got plenty spare in
case of problems, and we encourage learning in agriculture reducing
long term costs.
These two positives apply much less in the case of non food energy
crops. If there's a megadrought next year, we can reduce corn
consumption by cattle or by ethanol plants virtually overnight,
clearing a forest to plant food crops again is a little more time
consuming.
And it's not just fuel cells or PV that can benefit from learning
effects, agriculture can too, and forcing investment into agriculture
and prices for farm produce to levels where just enough is produced in
the average year, and too little, when there's a major problem,
doesn't seem to me the best way to insure food security.
David B. Benson
> (Powder
> River Basin coal goes for about $15/ton).
Transportation costs drive the price up to the $85 range.
David B. Benson
wrote:
> ... the less energy remains in the solid
> product.
I doubt this is the case for the Max Planck Institute method of
pressure cooking. All of the mertials inside the pressure
cooker remain inside, except water and maybe some VOCs.
> For cheap equipment that's not a problem, but for pressure vessels
> that need to be built to stand a potential thermal runaway and
> consequent explosion ...
the pressure vessel and the process, once started, is exothermic.