U.S.-FocUSed Biochar report - BioEnergy Lists

projects (p 81 of his thesis) doubled NPP by 2050. This would place the BBTV as consuming something closer to1/6 of the US NPP. He states that today’s NPP average conversion of incoming solar energy is about 0.3% (using180 W/m2 average). He says that a future conversion of 2% is possible. This is about half the theoretical limit forC-4 plants, thereby justifying a factor of 7 improvement as being possible.On p 56, Dr. Smeets also gave another reason for not using today’s NPP values:“The difference in yield is caused by the fact that in stable natural ecosystems, plants have passed their rapidgrowth phase. Food and energy crops are usually harvested during or soon after the rapid growth phase and havethus higher average yields.”In some Asian countries the human appropriation of NPP is much higher than the above postulated US factor ofabout 1/3. 41 See also additional comments on NPP in Subsection 5.5.4.5.5.3 Additional Clarifications.Additional carbon negativity. There are additional contributions to carbon negativity (carbon neutrality discussedbelow) beyond Biochar’s initial placement in soil, including:Intentional growth of biomass (mostly trees) where none previously existed sometimes going by the nameREDD. 42Increased above-ground growth following placement of the Biochar in the soil (and the same below ground inadded Biochar-caused roots, bacteria and fungus).Reduced need for fertilizerRetention of Nitrogen OxideLowered release of MethaneLowered release of particulates from open biomass combustionAugmented sequestered carbon both above ground and in the soil.- after the char has been placed in theground with augmented productivityReduced water pumping (the use of biopower to replace fossil sources is in the carbon-neutral category discussedbelow)Possible capture of CO 2 following use of the pyrolysis gases in a process known as Biomass Emissions Captureand Sequestration (BECS). 43We estimate 20-25% sequestration additional to the postulated 1 C-wedge that should be considered in valuingBiochar. This important aspect of Biochar has just begun to get research attention and is outside the scope ofthis Section.Varying carbon content of Biochar Char is often said to be about 85% carbon when produced at typicalslow pyrolysis temperatures. How to achieve the exact assumed 4:1 ratio of 4 B-wedges to1 C-wedge must be thesubject of a much longer study. Slow pyrolysis biochar production gives about this ratio, whereas fast pyrolysisbiochar production would require about a 6:1 ratio.The important fast pyrolysis yield reduction is counterbalanced, however, with the possible use of the HTC approachmentioned above. In HTC, about 97% of the carbon in the biomass can stay in the resultant product. 44So much is uncertain in this analysis that coming within 10% on the C-wedge number would be surprising, even ifperfect on the B-wedge values. In any case, the extra equivalent carbon reductions listed in the first paragraph ofthis subsection should make up the difference in Sequestration potential. We assume the 4:1 ratio for simplicity.41 http://www.worldwildlife.org/science/pubs/imhoff_nature.pdf42 http://www.cifor.cgiar.org/publications/pdf_files/cop/REDD_paper071207.pdf43 http://en.wikipedia.org/wiki/Bio-energy_with_carbon_capture_and_storage44 http://www.biochar.org/joomla/images/stories/Pechoelbrennen/MaxPlankCharcoal.pdf60U.S.-Focused Biochar Report:Assessment of Biochar’s Benefits for the United States of America