We did not consider biochar because of the confusion of types of biochar technologies and the poor characterization of the carbon balances for most of them. Carbon is lost in most of the biochar processes as I understand them, but a quantitative carbon balance for biochar is less clear. Compared to most soil residue management practices with are marginally effective at retaining surface crop residue carbon, it seems to me that biochar may be able to add a significant semi-permanent boost to soil carbon stocks.
But the whole biochar technology is poorly understood. For example, there issues of toxicity in the incorporation of biochar into agricultural soils that have not been adequately explored. Does fresh biochar release polyaromatic hydrocarbons that can be taken up by crops? A lot of research is needed before biochar is applied at large scales in our agricultural soils. I support funding that research right alongside the funding of research into oceanic crop residue sequestration. But, importantly, how often can biochar be used to store carbon in a given soil? Every year, for a hundred years as necessary, until our agricultural soils are nothing but biochar? Are our agricultural soils the correct place to sequester the excess fossil fuel carbon in the atmosphere? That fossil carbon came from deep sediments. The permanent solution is to return it to deep sediments. = Stuart = Stuart E. Strand 167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195 voice 206-543-5350, fax 206-685-3836 skype: stuartestrand http://faculty.washington.edu/sstrand/ -----Original Message----- From: Sam Carana [mailto:[email protected]] Sent: Friday, January 23, 2009 7:10 PM To: [email protected]; Stuart Strand; geoengineering; greenhouse effect; geo-engineering Subject: Re: [geo] Re: Crop residue ocean permanent sequestration The "only" method? Why not start with biochar burial? That would have the additional benefit of making soil more fertile, help water retention and prevent erosion. Current farming practices all too often result in loss of carbon from the soil, which eventually ends up in the atmosphere. This would also mitigate the point that Greg Rau brings up, i.e. that removing crop waste from the land would come with a need for additional fertilization of the soil. Apart from the benefits for the soil, it would seem to me that this a cheaper solution than to bury carbon deep underneath the ocean. Furthermore, some of the carbon could be used for industrial purposes, such as for making carbon fiber, in the building industry, etc. So, why not start with pyrolysis of organic waste at relatively low temperatures, and then using the char for agricultural and industrial purposes. Cheers! Sam Carana On Sat, Jan 24, 2009 at 4:55 AM, Greg Rau <[email protected]> wrote: > Congrats!. Will read with interest. In the meantime my questions are: > 1) does this differ in concept from Metzger and Benford 2001? > 2) crop residues contain other things besides C, such as N, P, trace > elements, etc. By removing these from land won't this require greater > fertilizer use to maintain crop production? > 3) Barring dumping in existing anoxic zones, might (some) decomposition in > water column/sed surface impact deep (and eventually via circulation, > surface) ocean chemistry and biology? > Thanks, > Greg > go dawgs > > We have just published the following peer reviewed article in Environmental > Science and Technology: > > > > Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon > Back to Deep Sediments > > Stuart E. Strand and Gregory Benford > > > > For significant impact any method to remove CO2 from the atmosphere must > process large amounts of carbon efficiently, be repeatable, sequester carbon > for thousands of years, be practical, economical and be implemented soon. > The only method that meets these criteria is removal of crop residues and > burial in the deep ocean. We show here that this method is 92% efficient in > sequestration of crop residue carbon while cellulosic ethanol production is > only 32% and soil sequestration is about 14% efficient. Deep ocean > sequestration can potentially capture 15% of the current global CO2 annual > increase, returning that carbon back to deep sediments, confining the carbon > for millennia, while using existing capital infrastructure and technology. > Because of these clear advantages, we recommend enhanced research into > permanent sequestration of crop residues in the deep ocean. > > > > Available on line here: > > > > http:// pubs.acs.org/journal/esthag > > > > or email me requesting a reprint > > > > = Stuart = > > > > Stuart E. Strand > > 167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195 > > voice 206-543-5350, fax 206-685-3836 > > skype: stuartestrand > > http:// faculty.washington.edu/sstrand/ > > > > Using only muscle power, who is the fastest person in the world? > > Flying start, 200 m 82.3 mph! http:// en.wikipedia.org/wiki/Sam_Whittingham > > Hour http:// en.wikipedia.org/wiki/Hour_record > > 55 miles, upside down, backwards, and head first! > > > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
