Monday, May 11, 2009

The Science of Biochar

The science of Biochar is just beginning. We've only just started thinking about restoring soils as a way to help both mitigate and adapt to climate change, but most people in the mainstream have hardly heard of Biochar.
Let alone understanding the implications and the potentially huge impact Biochar could have in helping our entire society become sustainable.

One of the primary reasons I put my career on hold and have been working full time trying to help start the Canadian Biochar Initiative was because I saw some potential with the technology, but it is only recently that I have begun to understand the magnitude of its potential for good.

I've been communicating a lot with people who have been talking about climate change recently. There are some who say that we don't have very much time before we need to start drawing down hard on atmospheric CO2.

It was Johannes Lehmann of Cornell University who first emphasized that Biochar "could remove billions of tonnes of carbon from the air each year".
That caught my attention, so I wanted to reproduce his calculations.

This is nothing to laugh at, because governments in Canada are now starting to spend increasing billions of our taxpayer dollars on schemes to reduce our "emissions intensity" with megaprojects like underground Carbon Capture and Sequestration (CCS) which would only reduce the projected carbon emissions from the Alberta Tar Sands by about 7.5% after about six years -- and would require an additional 20 to 50 years of substantial investment in infrastructure to have any significant impact at all.

It might also require that we use an additional 900,000 gigawatt-hours of energy -- per year! This is equivalent to hundreds of new nuclear plants or hundreds of thousands of Wind turbines. All this at a time when governments are running multi-billion dollar deficits.

We could end up spending trillions of taxpayer dollars undertaking a monumental task that ultimately ends up being fruitless -- especially if we find out 10 years from now that CO2 wasn’t the primary cause of climate change.

After all, we could let nature do the sequestering for us – by allowing nature to thrive – and then pulling the carbon out of the atmosphere as we pyrolyze the residuals in a process that also provides us with an energy surplus. This is the "magic" of Biochar!

At worst it would be environmentally benign and at best it could be tremendously beneficial with respect to food security, secondary environmental contamination issues like fertilizer runoff and leaching (which affects our oceans and other water bodies as well as our groundwater) and could possibly even help reverse desertification.

So even if Biochar could conservatively sequester 1 or 2 Gigatonnes of CO2 per year, that would still be 3 to 4 magnitudes of order greater than CCS.

And, interestingly enough, the Alberta Research Council has calculated that we might actually be able to utilize Biochar at a profit -- particularly for farmers!

Now, I live in Ontario, so I was only recently introduced to the Palliser Triangle in southern Saskatchewan and southeastern Alberta. I knew it was dry out west, but I learned that the Palliser Triangle actually covers more than 200,000 square kilometers of area and it's so dry that sand dunes actually cover more than 3,400 square kilometers of the region.

I completed a soil science course last year at the University of Guelph for the first time.
I've always been interested in Geography, so it was interesting to learned that only 5 percent (about 46 million hectares) of Canada's vast terrain is actually suitable for crop production and that 85 percent of this (about 39 million hectares) is in the Prairie Provinces.

I also learned that, in the long term, soil degradation is the most serious threat to the agriculture industry in Canada and that 5 percent of cultivated Prairie farmland is at high to severe inherent risk of water erosion, and that 20 percent of the cultivated land continues to be at risk of moderate to severe wind erosion.
Wow! Seems that our soils aren't robust and fertile as we once thought and we are degrading them at ever increasing rates.

What are the implications for future food security?

Now, getting back to the Palliser Triangle and Biochar.
200,000 square kilometers translates to 20 million hectares.

Now that I knew about the Palliser Triangle, I thought, "Well, if we could put 5 tonnes of Biochar on each hectare in this triangle this would translates to 100 million tonnes of carbon.
(Actually, if we assume that the permanently recalcitrant carbon in Biochar is only 80% then this is only 80 million tonnes.)

Since each tonne of carbon would be equivalent to 3.67 tonnes of CO2, this translates to 293.6 million tonnes of CO2.
Now, compare that to the "up to five million tonnes annually by 2015" for CCS.
That's more than Fifty Times (50X) the amount of carbon sequestered!

It also vastly exceeds the 67 million tonnes of CO2 equivalent emissions that the Tar Sands might reach by 2015. In fact, it's more than four times more!

So what's the economics of it?
I've estimated that for $200 million -- for research to prove that Biochar is either neutral or even beneficial to Canadian soils, we could sequester these 293.6 million tonnes of CO2.
That works out to a cost for the taxpayer of only $0.68 per tonne of CO2.

Of course this is simplifying the costs, but... maybe not, if we consider the increased yields for farmers and reduced soil erosion and potentially reduced need (and cost) for fertilizers, among many other benefits like protecting watersheds.
And this is where I started to think, maybe this has real possibility.

So I came back to the question of soil carbon.
I knew that in the past century as we've been plowing and essentially 'mining' our soils of nutrients that we have seen the organic carbon content in most fields go from about 5 percent down to about 3 percent.
I also remembered that the "Terra preta" soils -- those pre-Columbian soils that were created by humans in the Amazon Basin -- had, on average, about three times more soil carbon than in the surrounding poor soils.
I remembered from my soil course that some soils in Canada were very carbon deprived, and found out that the soils of the Palliser Triangle actually have some of the lowest soil carbon content in Canada -- somewhere around 1% soil carbon, which is quite low.

So, based on what I learned about soils in my Guelph University course I did a few simple calculations and I found out that adding 5 tonnes of Biochar per hectare would actually only increase the carbon content of the soils in the Palliser Triangle by about 0.2%, and if the average soil carbon content is only 1% right now and our target is to double it (to only 2%) it would take at least four applications of Biochar (at 5MG/ha) to get to 2% carbon content in the soil -- and this would be equivalent to 1.174 Gigatonnes of CO2 sequestration!
This very closely matched Johannes Lehmann's calculations. Dr. Lehmann had once said that the Earth's soils could remove between 5.5 and 9.5 billion tonnes of carbon from the air each year.

This amount of CO2 sequestration capability – on less than half of the total cropland in Canada – was already enough to offset all of the CO2 emissions from the Tar Sands for at least the next 17.5 years. It didn’t even account for the other 26 million hectares of land suitable for crop production in Canada that might also benefit from Biochar!
And it didn’t account for the fact that we might be able to bring our soil carbon content up to 3% or even 5% or more.

So, with Biochar, Canada could actually very quickly reach our Kyoto commitments -- and even go far beyond them.
What I realized was that Canada could even become a carbon negative country.

After all, according to official government statistics, Canada only produced 721 Megatonnes of greenhouse gas emissions in 2006 (carbon dioxide equivalent emissions).

So if we could sequester almost 300 Megatonnes of CO2 on just 20 million hectares of land, what if we were to add 10 tonnes of Biochar on each of the 46 million hectares of croplands in Canada?
I would think that we could draw down carbon pretty fast.

And, remember, my contact at the Alberta Research Council said that we could do it at a profit!


  1. Keep up the good work Lloyd. Make sure you set up to file these under different titles. You are a real encouragement to the AirTerra guys

  2. more natural gas is used making fuel from tarsand then if natural gas would be used if the natural gas was used as fuel.

  3. We are working with the Clinton Global Initiative on pilot pyrolysis plants to create bio char in Senegal, Mali, Haiti and Brazil.
    Technology from a French firm with 3 pilot plants providing carbon offsets for Air France.

  4. This sounds like a good scheme, but I've got a question on the detail. I don't mean to be critical, I just want to learn more.

    What happens to biochar if there isn't any life to bind it (if it needs any binding). The reason I ask is that while I know biochar is a fantastic growth medium for the microbes that work to enrich soil, I still think that those microbes and the other parts of the ecosystems that make soil work will need the right climate. The Palliser Triangle, with its sand dunes, seems like a place where even rich soil would have difficulty thriving. Some of Climate Change is already inevitable, and I don't see that making the Triangle more habitable. So, if you put biochar in the ground in dead environment, is there a chance that it (or a percentage of it) will just degrade into CO2 and leak into the air? I suppose much of it is very stable, as pi bonded carbon, but that raises the horrible possibility of resuspension in the atmosphere as Black Carbon aerosol.

    Is a climate that supports live, thriving soil a better climate for making biochar a secure long term carbon store and if so, what are the implications? Biochar does support soil life, but are there other necessary ingredients?

  5. I would like to know what the actual steps are to convert carbon dioxide emissions into carcon suitable for the soil. What energy needs to be consumed, or if it is relying on plants to pull the carbon from the air - what are they, where will they grow and and what is the scale necessary to make this kind of impact?

    I suspect the most important factor determing the the amount of carbon that can be maintained stably in the soil in the Palliser Triangel is rainfall. For microorganisms to interact with the carbon and create renewable soil, they need water. Once the microorganisms are thriving, soil maintenance such as the regular plowdown of green manure (fallow crops) will keep the soil healthy and the carbon levels constant. The productivity of the area should also dramatically increas so long as they don't ruin the soil with factory farming methods.


  6. Thanks for that, Bob. I can't imagine an area hosting sand dunes could have much rainfall.

    Another question I've got is one that's plagued me about bio-energy for some time. We're talking about soil carbon content. For carbon to be sequestered, it needs to stay in the soil, but does the growth of plants not take some carbon from soil and some from the air. I've heard it mentioned that trees add carbon to soil, but to all plants do that? If not, do we need to be careful about what we grow as feedstock for agrichar and ensure that it either increases or does not decrease soil carbon? And would the management (or lack thereof) of carbon in the soil where feedstock is grown not have implications for Lloyd's calculations above?

    I think I can answer your question, Bob, in rough terms, about converting carbon dioxide to agrichar. The first is using plants to convert the CO2 to biomass (during which my question above must be taken into account), then you do something like pyrolyzing the biomass. You heat it to something in the neighbourhood of 900 degrees (I think) in the absence of oxygen. Without oxygen, the biomass doesn't burn, but it chars into agrichar AND creates bio-gas (methane, etc.). Presumably, the gas can be recycled in the system to provide the heat necessary to continue pyrolysis and, again supposedly, there will be gas to spare. I've never seen an energy balance on even a theoretical example, but the idea is that if there is bio-gas left over after the energy needs of the process are met, then agrichar (biochar, whatever) is a carbon negative source of renewable energy.

    The point you raise about where feedstock will be grown is an important one. A study came out recently examining the carbon footprint of woodfuel heating (using biomass boilers) and it showed that if the areas where trees were grown was not naturally fertile enough to grow trees (rather than just grass) then bringing in the compost and fertilizer required to make the land suitable for trees would make the carbon intensity of woodfuel energy worse than that of natural gas. It's reminicent of bio-diesel with a higher carbon footprint than fossil diesel.

    Of course, agrichar might not need trees. It might be able to take any kind of biomass. I don't know.

  7. Could the residue from the crops grown by farmers in the Palliser triangle not be used to produce biochar, this would certainly help in improving soil condition and water retention capabilities in this semi-arid area?

  8. With respect, you are making an incorrect statement with respect to natural gas and oilsand recovery above. I am not saying this is you Andrew, but as much as some want to "tar" the oilsands with a nasty brush, it is important to be fair and not let opinion become "polluted" with ideology. Otherwise, you only lose your credibility as a critic. And all we really have as humans is our honour when you get down to it!

    Bitumen is now removed from sands at a temperature of 40 C. this is a vey low temperature requiring very little natural gas.

    I invite all the oilsands critics not to believe at face value the propoganda from certain environmental groups who use blatantly false or outdated tabloid style headlines only as a means to raise donations for their cause.

    Please do independent research and learn about how the oilsands are dramatically reducing their environmental footprint.

    Please be fair if not for them then at least for yourself.

    I have done my research and I am really proud of what the oilsands companies have been doing lately. I urge them to continue their great work and I am also confident that they will become some of the biggest investors in biochar technology as well.

    Kevin Aschim

  9. Hi Lloyd,

    I'm so happy to have discovered this blog. I believe we are of the same concerns and passions. Thanks for the insights you shared in this site. Keep up the good work!


  10. Don't believe in what biochar can do?
    Learn more about the future of agriculture with biochar, from the most complete book about biochar “The Biochar Revolution”
    Learn how to get terra preta!

  11. May I know what is your basis for saying that 1 ton of biochar is equivalent to 3.67 tons of CO2? Thanks


  12. CO2 is heavier that carbon.

    Thermal conversion of biomass to fractionate each component for highest value use.
    Several pathways exist; Fast & Slow Pyrolysis, Gasification and Hydro-Thermal Carbonization.
    The first two are known technology, what is new are the concomitant benefits of biochars for Soil Carbon Sequestration, for soil biodiversity & nitrogen efficiency, for in situ remediation of a host of toxic agents and as Feed supplements cutting the carbon foot print of livestock.
    Modern systems are Closed-Loop with no significant emissions. The energy return on energy investment (EROEI) ranges from 7:1 to 9:1. The general Life cycle analysis (LCA) is; Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration (= to 1 Ton CO2e) + Bio-Gas & Bio-oil fuels = to 1MWh exported electricity, so is a totally virtuous, carbon negative energy cycle. [1]

    A significant aspect of low cost, Biomass cook stoves that produce Biochar is removal of BC aerosols and no respiratory disease emissions. At Scale, replacing "Three Stone" stoves the health benefits would equal eradication of Malaria & Aids combined. [2]

    The future of biochar - Project Rainbow Bee Eater

    State Dept. Release;
    100 million clean-burning stoves in kitchens around the world.

    Recent NATURE STUDY;
    Sustainable Biochar to Mitigate Global Climate Change