Andrew et al
A few comments on this thread.
Ning Zeng has it right, statements that burying beats burning in all (or even
most) cases are not supported by the evidence.
This is a case with the details and circumstances matter.
If you have wet waste near the Mississippi and the alternative is combustion of
the waste in a purpose-built biomass to electricity facility (which will be
small, inefficient, and of high capital costs) then burial wins.
If you have somewhat dry waste near a coal-fired power plant then cofiring wins.
Marty said "fundamentally" it's better to bury them burn. Marty is smart guy.
We both have the curse or blessing of physics as a background. But I have to
say I am mystified how anyone can make any kind of fundamental claim that
either burial or burning is better. I don't see any evidence for that claim in
the paper.
Stuart said: "All of these arguments were answered last year when the paper
came out, but apparently you did not digest them then, so I will repeat,
briefly. Burning biomass for electricity or making ethanol avoids fossil fuel
carbon emissions = 30% of the starting biomass carbon. Biomass is a poor
fuel, better to bury it. Please read the paper. Or is there something about
3>1 that you don't understand?"
I don't think the problem is our failure to understand that 3>1, nor do I think
that this style of rhetoric helps settle arguments on complicated topics. In
this particular case, the 30% depends on a set of assumptions, which in some
cases might be true, in some cases burial is better than burning. However in
other cases (many) they're not true.
When you do the economic analysis in $/tC terms and finds that things that are
easy breeze by matter. Example: capital costs. If you have to build a purpose
built biomass facility than the capital cost will be well north of 2000 $/kWe
and it may look big compared to the equivalent cost of building the
infrastructure to do the burial. If, you're talking about retrofitting for
cofiring then the capex looks 5X smaller. Utilization of capital also matters,
biomass is a variable resource. One advantage of cofiring is that the capital
is used all the time, if there's no biomass you just use the coal. Where is
dedicated biomass systems must stand idle when there's not much biomass, when
you calculate dollars per ton you have less utilization per unit capital and
prices go up.
Here's some of our papers that address these points:
47. David W. Keith and James S. Rhodes (2002). Bury, burn or both: A
two-for-one deal on biomass carbon and energy. Climatic Change, 54: 375-377.
This paper was invited with the paper Marty referred to because that Steve
Schneider was concerned that the burial paper seem too much like advocacy, and
wanted to hear another point of view.
95. James S. Rhodes and David W. Keith. (2008). Biomass with Capture: Negative
Emissions Within social and Environmental Constraints. Climatic Change, 87:
321-328.
A more general overview of various pathways to negative
emissions.
64. Allen L. Robinson, James S. Rhodes and David W. Keith (2003). Assessment of
Potential Carbon Dioxide Reductions due to Biomass-Coal Cofiring in the United
States. Environmental Science and Technology, 37: 5081-5089.
This paper was an attempt to quantify the potential of cofiring by doing a
state-by-state match of biomass resources and coal-fired power. There are
obvious limitations to this analysis, but it will least it was an attempt to go
beyond gross national averages. It also contains a review of the status cofire
technology by Allen Robinson a colleague at CMU who is a combustion expert.
N.B., this paper has an error in one of the axis labels of the final figure.
Jamie: if you're reading please double check that we have a corrected version
up.
126. Jamie Rhodes and David Keith (2009). Biomass co-utilization with
unconventional fossil fuels to advance energy security and climate policy.
National Commission on Energy Policy
Finally, things look different again when you consider gasification pathways to
co-processing. Here the disadvantage of wet biomass is less important. This is
a report we wrote more recently summarizing these options for a major
Washington think tank.
All of these papers are available for free download at
http://people.ucalgary.ca/~keith/Other%20Energy.html.
To sum up, I am not claiming that burial is foolish. It's a good idea that make
sense under some circumstances. I am claiming that statements to the effect
that burial is fundamentally or obviously better is advocacy not analysis.
Yours,
David
-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Ning Zeng
Sent: Monday, September 13, 2010 6:40 AM
To: geoengineering
Subject: Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center,
Washington DC
Dear Andrew and all:
The question of bury or burn is an important one that is far from resolved. One
point emphasized by several people involved in implementing climate mitigation
strategies at the Heinz Center workshop last week is that in general, there are
many other competitions with biomass use as the total supply is limited by
available land. For example, two that are being strongly promoted at this
moment are long-term product use of wood by the forestry community, and biochar
by soil scientists+, in addition to burning for energy. CO2 storage in
geological formations are not yet practical at large-scale, so one can not
assume so (and yet most stabilization scenarios count a few wedges on that!).
At the end it will all come to the economics vs carbon/energy benefit, and most
likely each method will find its niche depending on the local circumstances and
carbon price. Plenty of research and real projects will have to be carried out
before we know how much, where and when for which method.
cheers,
-Ning
On Sep 12, 9:11 pm, Andrew Lockley
<[email protected]<mailto:[email protected]>> wrote:
> An interesting paper, but one which nonetheless does not consider the
> possibilities offered by Biomass Energy with Carbon Capture & Storage.
> If you can float crop waste down the Mississipi for sinking, you can
> float it down in dry bags for burning.
>
> Typically, CCS knocks about 20% of the energy output of a power plant
> (from memory). So, it still looks like it's worth burning the crop
> waste to recover the energy, then sequestering the CO2. (Although the
> 20% may rise if the carbon efficiency of the generation process is
> lower for crop waste).
>
> Further, the paper's comparison with natural gas isn't terribly
> helpful, as it's a particularly scarce fossil fuel. Coal would make a
> more realistic comparison, in the long term - dramatically reducing the
> benefit claimed.
>
> One further point is that sequestering CO2 rather than crop waste
> doesn't carry any risk of clathrate formation.
>
> Perhaps someone could do me the courtesy of pointing out any flaws in
> my analysis?
>
> A
>
> On 12 September 2010 21:55, Marty Hoffert
> <[email protected]<mailto:[email protected]>> wrote:
>
> > Maybe the attached paper will help: An early approach explaining
> > why, fundamentally, it's better to bury crop residue biomass than to
> > burn it for energy.
>
> > Marty Hoffert
> > Professor Emeritus of Physics
> > Andre and Bella Meyer Hall of Physics
> > 4 Washington Place
> > New York University
> > New York, NY 10003-6621
>
> >
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