Making Charcoal Counters Climate Change

September 27, 2008 at 12:41 pm 2 comments

Simpler Way To Counter Global Warming Explained: Lock Up Carbon In Soil And Use Bioenergy Exhaust Gases For Energy

ScienceDaily (May 12, 2007) — Writing in the journal Nature, a Cornell biogeochemist describes an economical and efficient way to help offset global warming: Pull carbon dioxide out of the atmosphere by charring, or partially burning, trees, grasses or crop residues without the use of oxygen.

When bioenergy is produced by pyrolysis (low-temperature burning without oxygen), it produces biochar, which has twice as much carbon in its residue than that from other sources. This makes bioenergy carbon-negative and improves soil health.

This process, he writes, would double the carbon concentration in the residue, which could be returned to the soil as a carbon sink. The exhaust gases from this process and other biofuel production could then be converted into energy.

This so-called biochar sequestration could offset about 10 percent of the annual U.S. fossil-fuel emissions in any of several scenarios, says Johannes Lehmann, associate professor of soil biogeochemistry in the Department of Crop and Soil Sciences at Cornell.

“Biochar sequestration, combined with bioenergy production, does not require a fundamental scientific advance, and the underlying production technology is robust, clean and simple, making it appropriate for many regions of the world,” said Lehmann. “It not only reduces emissions but also sequesters carbon, making it an attractive target for energy subsidies and for inclusion in the global carbon market.”

Most plants pull carbon dioxide out of the atmosphere and lock it up in their biomass or in soil organic matter. But taking this a step further, Lehmann recommends heating the plant biomass without oxygen in a process known as low-temperature pyrolysis. When returned to the soil, biochar creates a stable, long-term carbon sink.

“Biochar also has been shown to improve the structure and fertility of soils, to enhance the retention and efficiency of fertilizers as well as to improve the productivity of soil,” said Lehmann.

Capturing the exhaust gases from the pyrolysis process produces energy in such forms as heat, electricity, bio-oil or hydrogen. By adding the biochar to soil rather than burning it as an energy source (which most companies do), bioenergy can be turned into a carbon-negative industry. Biochar returned to soil not only secures soil health on bioenergy plantations but also reduces greenhouse gas emissions by an additional 12 to 84 percent.

Compared with ethanol production, pyrolysis that produces biochar and bioenergy from its exhaust gases is much less expensive, Lehmann said, when the feedstock is animal waste, clean municipal waste or forest residues collected for fire prevention.

Lehmann said that as the value of carbon dioxide increases on carbon markets, “we calculate that biochar sequestration in conjunction with bioenergy from pyrolysis becomes economically attractive when the value of avoided carbon dioxide emissions reaches $37 per ton.” Currently, the Chicago Climate Exchange is trading carbon dioxide at $4 a ton; it is projected that that the price will rise to $25-$85 a ton in the coming years.

MLA

Cornell University. “Simpler Way To Counter Global Warming Explained: Lock Up Carbon In Soil And Use Bioenergy Exhaust Gases For Energy.” ScienceDaily 12 May 2007. 15 September 2008 .

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Limitations Of Charcoal As An Effective Carbon Sink
ScienceDaily (May 4, 2008) — Fire-derived charcoal is thought to be an important carbon sink. However, a SLU paper in Science shows that charcoal promotes soil microbes and causes a large loss of soil carbon.

There has been greatly increasing attention given to the potential of ‘biochar’, or charcoal made from biological tissues (e.g., wood) to serve as a long term sink of carbon in the soil. This is because charcoal is carbon-rich and breaks down extremely slowly, persisting in soil for thousands of years. This has led to the suggestion being seriously considered by policy makers worldwide that biochar could be produced in large quantities and stored in soils. This would in turn increase ecosystem carbon sequestration, and thereby counteract human induced increases in carbon-based greenhouse gases and help combat global warming.
However, a new study by Professors David Wardle, Marie-Charlotte Nilsson and Olle Zackrisson at SLU, the Swedish University of Agricultural Sciences, in Umeå, scheduled to appear in this Friday’s issue of the prestigious journal Science, suggests that these supposed benefits of biochar may be somewhat overstated. In their study, charcoal was prepared and mixed with forest soil, and left in the soil in each of three contrasting forest stands in northern Sweden for ten years.
They found that when charcoal was mixed into humus, there was a substantial increase in soil microorganisms (bacteria and fungi). These microbes carry out decomposition of organic matter (carbon) in the soil, and consistent with this, they found that charcoal caused greatly increased losses of native soil organic matter, and soil carbon, for each of the three forest stands. Much of this lost soil carbon would be released as carbon dioxide, a greenhouse gas.
Therefore, while it is true that charcoal represents a long term sink of carbon because of its persistence, this effect is at least partially offset by the capacity of charcoal to greatly promote the loss of that carbon already present in the soil.
The study finds that the supposed benefits of biochar in increasing ecosystem carbon storage may be overstated, at least for boreal forest soils. The effect of biochar on the loss of carbon already in the soil needs to be better understood before it can be effectively applied as a tool to mitigate human-induced increases in carbon-based greenhouse gases.
Adapted from materials provided by Swedish University of Agricultural Sciences.

Swedish University of Agricultural Sciences. “Limitations Of Charcoal As An Effective Carbon Sink.” ScienceDaily 4 May 2008. 15 September 2008 .

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2 Comments Add your own

  • 1. Erich J. Knight  |  September 29, 2008 at 5:00 am

    The Rest of the Biochar Story:

    Charles Mann (“1491”)in the Sept. National Geographic has a wonderful soils article which places Terra Preta / Biochar soils center stage.
    I think Biochar has climbed the pinnacle, the Combined English and other language circulation of NGM is nearly nine million monthly with more than fifty million readers monthly!
    We need to encourage more coverage now, to ride Mann’s coattails to public critical mass.

    Please put this (soil) bug in your colleague’s ears. These issues need to gain traction among all the various disciplines who have an iron in this fire.
    http://ngm.nationalgeographic.com/2008/09/soil/mann-text

    I love the “MEGO” factor theme Mann built the story around. Lord… how I KNOW that reaction.

    I like his characterization concerning the pot shards found in Terra Preta soils;

    so filled with pottery – “It was as if the river’s first inhabitants had
    thrown a huge, rowdy frat party, smashing every plate in sight, then
    buried the evidence.”

    A couple of researchers I was not aware of were quoted, and I’ll be sending them posts about our Biochar group: http://tech.groups.yahoo.com/group/b…guid=122501696

    and data base;
    http://terrapreta.bioenergylists.org/?q=node

    I also have been trying to convince Michael Pollan ( NYT Food Columnist, Author ) to do a follow up story, with pleading emails to him

    Since the NGM cover reads “WHERE FOOD BEGINS” , I thought this would be right down his alley and focus more attention on Mann’s work.

    I’ve admiried his ability since “Botany of Desire” to over come the “MEGO” factor (My Eyes Glaze Over) and make food & agriculture into page turners.

    It’s what Mann hasn’t covered that I thought should interest any writer as a follow up article.

    The Biochar provisions by Sen.Ken Salazar in the 07 farm bill,

    Dr, James Hansen’s Global warming solutions paper and letter to the G-8 conference last month, and coming article in Science,
    http://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf

    The many new university programs & field studies, in temperate soils

    Glomalin’s role in soil tilth & Terra Preta,

    The International Biochar Initiative Conference Sept 8 in New Castle;
    http://www.biochar-international.org/ibi2008conference/aboutibi2008conference.html

    Given the current “Crisis” atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?
    Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth), is gaining widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!

    This technology represents the most comprehensive, low cost, and productive approach to long term stewardship and sustainability.
    Terra Preta Soils a process for Carbon Negative Bio fuels, massive Carbon sequestration,10X Lower Methane & N2O soil emissions, and 3X Fertility Too. Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration.

    Carbon to the Soil, the only ubiquitous and economic place to put it.

    Erich
    540 289 9750

    Reply
  • 2. shadowphenyx  |  October 1, 2008 at 4:18 am

    At the same time however while I “favour” the idea of using biochar I have also run across evidence that it biochar increases micro-organism activity. This then counters its sequestration capability by increase carbon release from the soil (because of increase microbe activity). [Which makes sense after the fact]

    Of course the soil is still more fertile overall because of biochar.

    Ultimately even biochar may not be a one shot solution to soil and carbon releases that influence climate change due to changing land use.

    An environmental biologist,
    Sunny Lam

    Ffenyx Rising
    http://ffenyx.wordpress.com || http://www.linkedin.com/in/sunnylam

    Reply

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