Charcoal: The Next Green Alternative
by Jeremy Elton Jacquot, Los Angeles on 05.23.07
As hard as it may seem to utter "charcoal" and "green" in the same sentence (go on, give it a try), Johannes Lehmann and his colleagues would have you believe that charcoal, or as it's known by researchers in the field, "biochar," is the next big thing in the fight against global warming. In essence, Lehmann, an associate professor of crops and soil sciences at Cornell University, proposes that biochar, which is produced when biomass is baked in the absence of oxygen through a process called pyrolysis, be buried, or "sequestered," in the soil as an alternative approach to tackling climate change.
Results from his research indicate that not only does biochar sequestration keep carbon dioxide from reaching the atmosphere; it actually extracts the greenhouse gas and helps decrease atmospheric concentrations. Although burning wood waste or ethanol made out of corn is considered "carbon neutral" because the carbon dioxide released in the process will be reabsorbed by other plants (i.e. no net gain or loss barring the effects of deforestation and soil depletion), sequestration is considered a "carbon negative" process since there will be an actual net decrease in the carbon dioxide concentrations.
In an article he published in the latest issue of the journal Nature, Lehmann wrote that "Our calculations suggest that emissions reductions can be 12 to 84 per cent greater if biochar is put back into the soil instead of being burned to offset fossil-fuel use."
While not a new process (Lehman says its use goes back hundreds of years to the Amazon Basin), interest in biochar didn't pick up steam until just recently as the increasing focus on global warming by the world community pushed scientists and policymakers to find new, viable solutions. "Three years ago (biochar) was not considered (for sequestration), but now people are starting to. It's gaining momentum," he says.
Lehmann and his colleagues suggest that biochar could be mixed with topsoil in farming to remove the carbon from the crop's lifecycle, an effect that, when magnified over several countries, would result in a sharp reduction of atmospheric carbon. They argue that the technology is already available and that the pyrolysis process, which also produces biofuel in the form of bio-oil, could make biochar use an economically attractive proposition. "The biophysical benefits are now clearly spelled out and far enough advanced that economists can help to find opportunities to make it work," Lehmann said in a recent interview.
::Biochar turns a negative positive
See also: ::Soil Color = Carbon Content: Sequestering Useful Carbon, ::A New Twist on Using Wood for Fuel
It makes some sense. We got into this mess because we took carbony black stuff out of the earth (petroleum) so putting carbony black stuff back into the earth might restore the balance, and save our asses. Or something like that.
Can you tell I'm not a chemical engineer?
I've read about this before and there's one thing I don't quite understand.
I take biomas (sawdust, switchgrass, whatever) and I bake it in the absence of oxygen. The result is charcoal, similar to what I to BBQ burgers with in the summer.
At that point, it's got energy in it. why would someone bury it instead of burning it to generate electricity?
What's the driving economic factor? If it were a by-product that was being buried, I could see it.
But we'd be burying something with real value. Seems it'd be difficult to convince people do do this.
Or is this something that governments would use?
The thing about biochar is that it creates an extremely nutritive soil source that is less easily eroded. They found patches of fertile topsoil in South America where there are generally fairly unfavorable conditions.
From Discover Magazine - "While most Amazonian earth is notoriously nutrient poor, yellowish, sterile, and unscented, there are extensive patches of soil that are mysteriously dark, moist, fragrant, and filled with insects, microbial life, and organic matter. Scholars have come to realize that by devising a way to enrich the soil, the early inhabitants of the Amazon managed to create a foundation for agriculture-based settlements much more populous than scholars had thought possible."
Considering the state of industrial agriculture right now, once the oil is either gone or prohibitively expensive, there will likely be massive food shortages. We have engineered cash crops to be entirely dependent on petrochemical-based fertilizers, pesticides, and herbicides, which is in turn mostly due to the sheer volume of topsoil that is carried away every year. Biochar is an organic highly nutritive substance that could help us regain usability of the massive amounts of land (basically most of the rural midwest) that have been stripped of their beneficial topsoil.
If we did that, coupled with other more ecologically wiser tactics such as implementing biodiversity and planting perennials as opposed to annuals (as well as making it a community thing again (SUPPORT LOCAL ETC.)) we'd probably get through peak oil much easier.
Here's a great article on biochar from Discover Magazine:
http://discovermagazine.com/2007/apr/black-gold-of-the-amazon
Anastasia,
What you are referring to also has the name "terra preta del indio", or just terra preta. I wrote a blog entry on it a while back, which you can see if you'd like:
It's amazing to see the difference between typical Amazonian soil and terra preta. Also, the fact that these soils exist despite a complete lack of maintenance for hundreds of years after their creators left or died off says that terra preta is also an excellent sequestration source. At least for a few hundred years.
Is charcoal more valuable as a fuel then something to enhance biomass production? Will market forces keep charcoal from the soil?
It depends partly on how much value the charcoal holding decision maker places on the health of our limited soil resources. For producers not maintaining soil, part of the price they get for their crop is lost soil health and dropping yields. To maintain soil health, land managers have to actively choose to retain and or build soil carbon. Largely because of charcoal's recalcitrance, adding charcoal appears to be the single most efficient long term practice available to conserve and build soil carbon. To some significant part of the population, that awareness will result in elasticity of demand for agrichar.
For the cash-flow-driven cold-hearted bean-counter approach (not that that's a bad thing) agrichar pencils out to having fundamental value, but only for those wise enough and willing to take the risk to wait on it. Since that's what farmers do for a living, you can expect agrichar's target audience to be receptive to the following concept.
Charcoal added to soil must increase biomass production to compete against fuel. One of the criteria that biomass producers will be mulling is one of biomass break even - at what point is the net increase in harvested biomass expected to equal the net biomass returned to the soil as biochar? Anything less than say three years is going to be fairly compelling. Biochar seems capable of breaking even on a biomass basis within a few years given the right circumstances, thus the interest. The sweet thing about the biomass break even approach is that it doesn't much matter what the fuel value of the biomass is - the question becomes "can you afford to wait to sell much more later by selling a little less now?".
If the net biomass produced is of higher value (grain, timber) than the charcoal feedstock (stover, slash pile), break even periods on the order of decades can become attractive.
"Why not burn the charcoal for energy?" -- because this produces exactly the opposite effect of what they're after. Burning carbon produces carbon dioxide.
Better: Pyrolysis takes a complex material (wood), and drives off shorter hydrocarbons (it breaks down complex hydrocarbons into hydrogen and carbon and shorter hydrocarbons). The shorter hydrocarbons are *cleaner burning* than the wood would have been, because you've already separated them from some of the carbon. So pyrolysis, while it does take energy, can also produce energy -- more than enough to be self-sustaining (given a supply of wood to work with).
Best: Putting the carbon in the soil has many, many benefits over putting it in the air -- increased fertility (which means plants that take CO2 and produce wood will grow faster and better and do more of that), heavy-metal and other pollutant absorption (there's a reason carbon (activated charcoal) is used in gas masks and aquarium filters), and more.
Burning the carbon to produce a little energy and a lot of CO2 is simply not worth the loss of the other benefits.
This could be a great opportunity for the fast-growing willow hybrids. They'll grow into "mature" trees in as little as five years, and are great for turning into soft charcoal, which can be returned to the soil to make the next generation of trees grow even faster and better, while pulling the carbon dioxide out of the atmosphere.
This makes no sense at all.
Where does the energy come form to heat it? Why would you grow plants to burn them, when you might need food?
Are you suggesting to cut down plants to burn and bury them, as something to do to pass time?
How would this scale, should 500 million people do this every day to so that another billion can drive cars?
Where is the land to do this, are you going to use crop land, how many million square miles would be needed?
Think about, labor force, land area, current land usage, and time whenever some one suggests growing anything with reference to biofuel or carbon sinks.
good answers.
How is biochar different from just turning the fields under? old fashioned fertilizer
I could imagine a logging company having biochar cookers hanging off the back of their equipment to do this. in that environment they probably won't want to or be able to till. also reduce fire hazard.
Seems like a lot of trouble though
good answers.
How is biochar different from just turning the fields under? old fashioned fertilizer
I could imagine a logging company having biochar cookers hanging off the back of their equipment to do this. in that environment they probably won't want to or be able to till. also reduce fire hazard.
Seems like a lot of trouble though
I've read about this before and there's one thing I don't quite understand.
I take biomas (sawdust, switchgrass, whatever) and I bake it in the absence of oxygen. The result is charcoal, similar to what I to BBQ burgers with in the summer.
At that point, it's got energy in it. why would someone bury it instead of burning it to generate electricity?
What's the driving economic factor? If it were a by-product that was being buried, I could see it.
But we'd be burying something with real value. Seems it'd be difficult to convince people do do this.
Or is this something that governments would use?
Talking about sequestration is a red herring here. If nothing were done to the biomass (wood chips from lumber processing, corn husks from farming, whatever) the CO2 wouldn't just escape into the air. It is only by mis-management of the biomass (burning) that the CO2 would go into the air.
How does this charcoal plan compare to simple composting? That gets the same (if not better) benefit to the earth and happens naturally...
I suppose that makes sense since charcoal contains a lot of "buckyballs" or (C60) carbon atom based molecules resembling structures of soccer balls. This heavily double bonded structure serves as a supernucleophile that can bond with CO2.
Controlling the reaction however may be a problem. Pyrolysis is described as a reaction closed off from molecular oxygen but Lehman's plan of putting this material in the soil is going to expose the charcoal to the open atmosphere made up 20% of oxygen. So, I wonder if it would deplete the atmospheric oxygen that we kinda want to keep around.
And plants require CO2 for photosynthesis and ultimately for glucose production. How are the plants going to grow if the immediate carbon dioxide is removed from the air by the charcoal? Lehman should consider mixing it with the topsoil only during off-season then, or he might get a lot of lawsuits from angry farmers.
Many years ago, they used to make charcoal out in the forest. They would simply cut the trees in the area, stack it up, light it and make charcoal. Not as sophisticated as today's methods, but still effective. Then the charcoal would be loaded into sacks and taken out on horseback. Remnants of those charcoal flats are still present today.
Every time I worked around these flats I noticed that the trees were bigger on the fringes of the flats. No trees grew on the flats themselves. Why is that?
Well, the increased amounts of potash on the fringe areas and a better carbon to nitrogen ratio (C:N). However, the carbon amounts on the flats are too high to be of any use, and has effectively sterilized the site.
Seems to me you can go overboard with carbon in the soil.
Not surprisingly, everyone associates the production of biochar and charcoal with the partial pyrolysis of wood waste. So did I.
Except that was impossible in the context of the Amazonian Indians who simply lacked the technology.
I figured out how they did it using corn stalks. Read about it in the blog that I am maintaining. It is actually quite amazing.
http://globalwarming-arclein.blogspot.com
One thing, open traditional charcoal making had a yield of 20% Using a closed oven - I describe a farm friendly system - that yield can easily jump to 40% and perhaps close to the 80% theoretical.. This is a huge difference
Do not forget that something has to act as the fuel and that quite properly should be the volatiles out gassed rather than the charcoal which provides a much lower energy.
Any left over can be shipped as fuel.
I must admit that I am getting a touch tired of the fuzzy thinking supplied by the promoters of pyrolysis equipment. However economic common sense will eventually straighten it out when they actually know what is permitted.
Something about this seems very, very fuzzy math. Not too far away from ethanolonomics.
Yeah, guys, I'm with you, this sounds really terrible. We should just keep mining potash and drilling for oil, and use that to grow crops. And we should keep using those industrial methods for farming. Because this sounds like fuzzy thinking, right? I mean, if we keep doing what seems to be working now, what could possibly go wrong?
I'll be out shopping for an Escalade!