The problem with using terrestrial biomass residues to combat CO2 accumulation is that there is a limited supply that is available for human use without doing environmental damage. These consist mainly of crop residues from high yielding agriculture and managed forests. There are competing uses for this biomass in terms of CO2 impacts: energy production, soil amendment (including biochar), and burial. Each of these uses has impact on CO2. It appears to me that we are in agreement on ranking in terms of the efficiency with which the limited biomass resource is used in terms of its carbon sequestration efficiency. My assessment is:
1. Burning with carbon capture (BECS), somewhere higher than 100%, maybe 115%; 2. Burial, including CROPS, about 90% 3. cellulosic ethanol with carbon capture, about 80% 4. biochar about 70% (50% in the soil, 20% energy capture) 5. burning or cellulosic ethanol without carbon capture, about 30% 6. Leaving it on no till soil, less than 10% Are there problems with this ranking (if not the numbers)? So if using this limited resource for carbon capture most effectively is the top priority, then we can wait a few years for BECS to be practical and do that intensively. In the meantime we can start working on all of the others as well, including burial and CROPS. Economics are another matter. We think we could do CROPS across basins for about 70 euro/t C, although some local areas may be able to do it for much less. David can give us the BECS estimates. I hope that they are less, but one has to worry about the intensive capital investment required. Still we have to build CCS plants anyway so why not BECS? One answer might be that gas and even coal are more economical use of the capital investment for the plant operator, since they are better fuels. It looks to me that subsidies will be required for CCS and BECS, either by carbon tax or carbon market, so why not for CROPS and burial as well? It will depend on how the market works out and whether cost and efficiency estimates can be attained. But if the cheapest use has a low carbon sequestration efficiency (such as burning without carbon capture or cellulosic ethanol) it is a waste of the carbon capture potential of the biomass. Most people look at biomass and see a valuable source of energy. Lots of research is being directed to making portable fuels from lignocellulosic biomass. Energy production is valued a lot more than carbon sequestration. But if fuel production is done without capture and storage of the CO2 from the process, it will not have as big an impact on atmospheric carbon as burial would. So to me, it is a matter of priorities: energy production or reducing atmospheric carbon. There are lots of successful carbon free ways to make energy, especially with stationary sources, but not that many ways to sequester carbon. Presently, all of our research into carbon sequestration is on one technology, CCS. That seems to me to be a risky policy, where there are good alternatives waiting. = Stuart = Stuart E. Strand 490 Ben Hall IDR Bldg. Box 355014, Univ. Washington Seattle, WA 98195 voice 206-543-5350, fax 206-685-9996 skype: stuartestrand http://faculty.washington.edu/sstrand/ From: geoengineering@googlegroups.com [mailto:geoengineer...@googlegroups.com] On Behalf Of Marty Hoffert Sent: Wednesday, September 15, 2010 6:11 AM To: ke...@ucalgary.ca Cc: z...@atmos.umd.edu; geoengineering@googlegroups.com; James Rhodes Subject: Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC I agree with David that whether to bury or to burn depends on details like whether you can burn the biomass AND bury its CO2, and whether you are looking at methane or coal as the alternate fuel for generating electricity. A big problem is that we have too few pilot plants measuring actual performance versus idealized limits in parameter space. This is a problem for all alternate energy sources. People get into huge arguments over these numbers and come to different conclusions about a technology's viability. I like to think we engineer/applied physics types are ethically compelled to abandon our beautiful theories in the face of ugly facts -- something our social science colleagues aren't quite as obsessed about. The reason I circulated that paper from climatic change was to stimulate quantitative discussion & if it did I'm happy. Marty Hoffert Sent from my iPhone On Sep 14, 2010, at 8:42 PM, David Keith <ke...@ucalgary.ca<mailto:ke...@ucalgary.ca>> wrote: 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: geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com> [mailto:geoengineer...@googlegroups.com] 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 <and...@andrewlockley.com<mailto:and...@andrewlockley.com>> 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 > <marty.hoff...@nyu.edu<mailto:marty.hoff...@nyu.edu>> 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 > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>. 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