John and ccs: There are many estimates of available biomass, although not many for CDR (through Biochar, BECCS, etc). A recent one (still not for CDR) that seems to have been well done is in a new WF report at this site (especially its Section 5 and several appendices):
http://wwf.panda.org/what_we_do/footprint/climate_carbon_energy/energy_solutions/renewable_energy/sustainable_energy_report/ I believe WWF can be assumed to be cautious on over-use of the global biomass resource. In this study for 2050, their total use of biomass is about 40% of the total energy demand - which is mostly renewable - and at a total of about 250 EJ/yr (possible because of assumed aggressive energy efficiency estimates). Their Fig. 5.1 says they are using about half of the technically available biomass - and they barely utilized any of the tremendous land area now being used for livestock. Because they calculate everything in energy (Exajoule) terms, we need to use a factor about 30 GJ/tonne C to obtain that a projected total carbon in biomass use (in 2050) of about 100 EJ converts to about 3.3 Gt C/yr (about half of today's fossil use/deposition of carbon). To get this same amount as Biochar (not considered at all by WWF), we would need to employ approximately twice as much input biomass - about the amount shown as technically available in their Fig. 5.1. I think this is a feasible goal. To check on its reasonableness, I need to get more deeply into the assumptions, but the yield values in Table C-2 seem OK (on the order of 4-6 tonnes C/ha-yr.) But your question relates to all CDR. New extra standing biomass is possible beyond the above. Today photosynthesis on land has an NPP (Net Primary Productivity) of about 60 Gt C/yr. If this were increased to 70 (or 80), even before any additional harvesting, there could be a huge annual CDR increase of 10 (to 20) annual Gt C. Eventually this new added standing biomass can/should also be converted to Biochar (divide these annual C-values by 2 to get Biochar). Of course with Biochar there are additional annual out-year sequestration benefits (both carbon neutral and carbon negative). I believe there are eventual combined benefits from Biochar that are from 50% to 100% of today's fossil annual C-inputs. Not to be sneezed at - and larger than any other approach I know of. Hope this WWF reference is helpful in answering your question below on Biochar being "scaled enough". Other thoughts on this? Ron ----- Original Message ----- From: "John Nissen" <johnnissen2...@gmail.com> To: "geoengineering" <geoengineering@googlegroups.com> Cc: "John Nissen" <j...@cloudworld.co.uk>, "Peter R Carter" <petercarte...@shaw.ca>, "Anthony Cook" <wynotpoint...@yahoo.com>, "Ron Larson" <rongretlar...@comcast.net>, "Sam Carana" <sam.car...@gmail.com> Sent: Tuesday, March 6, 2012 7:02:52 AM Subject: [geo] Rapid ocean acidification militates rapid CO2 removal (CDR) [Resent with correction] Hi all, Is there an alternative to rapid CDR to reduce the atmospheric CO2 level and hence slow ocean acidification? Acidification is progressing at the fastest rate for 300 million years, faster even than in the PETM [1], and spells catastrophe if not curbed over the next decade or two. I am supporter of biochar for CDR on a large scale. But few people think biochar can be scaled enough to actually start reducing the atmospheric CO2 level in the face of CO2 emissions set to climb for decades. So we need a combination of low to medium cost CDR schemes, capable of scaling to the very large. Yesterday I heard about a scheme for use of solar energy (e.g. in Sahara) to power the scrubbing of CO2 from the atmosphere and the production of hydrogen from H2O. The hydrogen would then be combined with the captured CO2 to create a carbon-neutral hydrocarbon fuel, which could then be cheaply and efficiently piped to countries wanting a green energy source, e.g. for cars and electricity generation. Apparently it's much cheaper and more efficient to pipe liquid fuel than transmit the equivalent electric power over the same distance. Cheers, John P.S. If hydrogen can be produced from H2O, could a hydroxyl byproduct be used for combination with scrubbed methane (CH4) to produce further carbon-neutral fuel? Atmospheric methane levels are rising ominously. [1] http://planetark.org/wen/64838 -- 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. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- 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. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
