Jim, CROPS would emulate the action of rivers, which during storms carry huge amounts of terrestrial biomass to burial in the near shore and deep ocean. The ability of terrestrial plants to reverse the anthropogenic accumulation of atmospheric CO2 is clearly evident in the Keeling curve. Every summer CO2 levels fall dramatically due primarily to terrestrial plant growth in the northern hemisphere. In the following autumn and winter respiration returns that carbon back to the atmosphere as the biomass rots on the soil surface. If that process can be interrupted by sequestering terrestrial biomass production that is presently under human control without unsustainable environmental damage, then we should do so.
= 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: jim thomas [mailto:[email protected]] Sent: Thursday, September 16, 2010 12:21 PM To: David Keith Cc: Stuart Strand; [email protected]; [email protected]; [email protected]; James Rhodes Subject: Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC David Apologies. That was not supposed to imply that you had lied but rather that those who make claims that biomass is carbon neutral are, in my experience, either practicing wishful thinking or attempting to mislead. I wasn't actually meaning to put you in the latter camp but i understand, given where we stand in other debates, how you assumed this was an attack. For now.. chill out, no attack intended. Second I was replying in general terms to a set of general assertions in an email and not to a peer-reviewed paper so no I didn't provide footnoted references. Let me read the paper you are referring to and i'll get back to you. Third, glad to hear there is some agreement that using purpose grown biomass for sequestration (whether burned, buried or biocharred) doesn't make sense. Looking at the figures on "earth overshoot" and the dire state of ecosystem collapse documented in the millennium ecosystem assesment I can't help but concluding there's no spare stock of existing 'waste' biomass sensibly available for energy use either.... when in balance, nature doesn't really do wastes... go well Jim On Sep 16, 2010, at 2:27 PM, David Keith wrote: Jim "Lie" is a pretty strong word. What specifically do you think I lied about? Can you back this claim up? Is this really the way you want to engage in public debate on issues where we must make sensible choices to protect our environment? Two responses, one general one specific: First, your claims about the efficiency of cofiring to not match an extensive body of literature based on widespread industrial experience. While there's nothing magic, about peer-reviewed literature, and experts can certainly be wrong, I think that the standard of evidence here needs to be a little higher than pure assertion and reference to journalistic accounts. You might start out by pointing out specific errors in the discussion of biomass combustion efficiencies in our co-fire paper or one of the many papers we cite therein. For example, there are a number of fine papers on the energy requirements for biomass transportation. I think you need to provide some pointers to why these are wrong. Second, I agree with you that there's a great deal of over promotion about the speed and productivity of biomass regrowth and about offsets. For that reason, I have I have spent a fair amount of time argued against use of purpose grown biomass because it takes so much land for nature. I can point you to a nice section in my student Jamie's thesis that documents the over estimates of biomass availability by some who promote BECS. Indeed on closely related point, we just got a paper into ES&T that examines biomass emissions from fossil fuel production, finding that, for example, clearing of peat lands for oil sands operations can have a surprisingly large emissions, and have a very long time horizon because of the slow (or not) recovery of the peat. If we tried to solve a significant part of the climate problem using large-scale purpose grown biomass we would, to put it bluntly, create an environmental disaster. So I think on this one we may be on the same side. It would be nice if here and elsewhere you would do a bit more work to check a person's views before you attack them. However, when it comes to use of waste fuels (the topic of our biomass cofiring paper) these arguments aren't relevant. Of course there are other issues, nutrients, emissions from transportation of the fuel that have been discussed in this thread and elsewhere. There are no free lunches here. Yours, David -----Original Message----- From: jim thomas [mailto:[email protected]] Sent: Thursday, September 16, 2010 10:51 AM To: David Keith Cc: Stuart Strand; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; James Rhodes Subject: Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC On Sep 16, 2010, at 11:38 AM, David Keith wrote: while cofiring biomass in coal-fired power plants without capture does not rank on your list at all, because there is no capture, it still avoids emissions of carbon. And because the capital cost of retrofitting plants large coal plants for biomass co-feed is very low and their combustion efficiency (for the biomass) is high this can be a very cost-effective way to reduce carbon emissions with biomass. Of course, it's not sexy and it's limited. David this simply isn't right. Firstly there IS carbon emission. Depending on how wet your feedstock, is biomass can in some casess emit more co2 per kilowatt produced than coal - thats real co2 aloft in the atmosphere for the next century. Whether that Co2 can subsequently be quickly fixed by theoretical replacement plants depends on what those plants are and how assiduosly they are managed. At present most co-firing of coal for electricity is using woodchips and other forest biomass. Releasing the carbon from a mature tree takes seconds, refixing it in another mature tree takes decades - maybe as long as seventy to a hundred years. All of that time the initial Co2 released is still aloft and still impacting the climate. That biomass can't even pretend to be carbon neutral for several decades and as we all know timeframes are critical in addressing climate change. Environmental journalist david baumann puts it starkly: "it would take over 100,000 one-year old trees to equal the weight of a 50 year old tree of similar species. Five year old trees take around 30,000. So you see for every tree we cut down and burn we'd have to plant 100,000 to resequester that much carbon in one year, 30,000 in five years. We'd also have to find the space to plant them." . The orthodoxy used to be that you can just plant fast growing eucalypts to sequester the CO2 faster than the older trees but that was based on a single study from the 1960's only applicable to one particular forest type and in fact its now understod that old growth forests sequester much more carbon than young plantations and that for the first 20 years or so a young plantation that replaces old growth is stil giving more co2 into the atmosphere than its fixing. Moreover the carbon footprint of bringing biomass to the power plant is not insignificant as biomass is heavy stuff with low energy content (heavier when wet but drying consumes space and energy too). Heres one quick back of teh envelope calculation on that: a standard 40 ton truck full of recently harvested woodchips will emit close to a kilogram (0.91kg) of CO2 for every km that it drives when delivering those woodchips for burning at a biomass electricity plant. Even a smallish 50MW plant would require 12750 such truckloads per year. At an average distance for sourcing woodchips of 68 km, that amounts to almost 790 tons (788,970 kg) of extra CO 2 emissions per year just for transport of wood chips alone. or put another way an additional 15 tonnes of Co2 per megawatt. Lets say instead of wood you can use a biomass feedstock that replenishes quickly such as annual crops, grasses or algae. (This doesn't address the transport problem in fact it worsens it- you would likely need more truckloads of crop residue than woodchips to get teh same energy output). As Andrew correctly noted, production of agricultural biomass feedstocks have significant greenhouse emissions associated with them. The more material you take from the land for burning, the less you have to replenish soil fertiity and hence the more nitrogen fertiliser is required to maintain productivity. Fertiliser production is responsible for approximately 1.2% of total GHG emissions - equivalent to the full greenhouse gas emissions of Indonesia or Brazil. In the US alone thirty percent of energy use in agriculture is accounted by fertilizer use and production. Thats before acount for nitrous oxide emission from fertiizer applications and then again any methane or nitrous emissions form eutrophication and runoff into dead zones such as the gulf of mexico. Algae is no better - commercial freshwater algae systems require higher concentrations of fertiliser than corn because they have no soil to pull nutrients from and we know what large scale saltwater algal production looks like - its called ocean fertilization and it raises its own problems. You can harvest wild algae from eutrophic systems and deadzones but thats building dependence on an ecoloically unhealthy feedstock for your energy needs. Even before you plant biomass feedstocks there will be significant soil carbon release from land clearances and land use change associated with turning so-called 'marginal'/unproductive lands over to biomass cropping. The Stern report identified a full 18 percent of climate gas emissions were the result of land use changes, second only to emissions from the power sector. This is the reason why the folks who initially argued for biomass to be counted as carbon neutral within the IPCC last year admitted they had made a 'critical accounting error' (searchinger et al) and so on... The claim that industrially burning biomass for power 'avoids emissions of carbon' is at best unexamined wishful thinking, at worst an outright lie. Jim Jim Thomas ETC Group (Montreal) [email protected]<mailto:[email protected]> +1 514 2739994 Jim Thomas ETC Group (Montreal) [email protected]<mailto:[email protected]> +1 514 2739994 -- 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.
