“Biochar Will Save the World!” proclaims a group page on Facebook.  Popular mechanics writes of an “ancient charcoal” that can “put the brakes on global warming.”  More than its prospects as a carbon sink or a fuel, biochar has massive prospects for development (the economic kind) for developing countries and emerging markets.  But is it really that simple? A very wise Finance professor* once told me, “Anytime anybody tells you they have a market for that, be very suspicious.”  It’s not that biochar couldn’t work, but that the market to make it work would have to be nuanced and highly regulated.

“One of the dangers of a biochar industry in developing countries is that you can divert your biochar to fuel or that you can somehow create more of a demand for wood which would be completely counterproductive.  What is a more sustainable system is to use agricultural and wood wastes,” explains Dr. Simon Shackley, at the UK’s Biochar Research Institute in Edinburgh.

Biochar as a fuel is in the middle of a hierarchy of fuels commonly used in developing countries. Dr. Shackley explains that the poorest tend to use wood, then charcoal, then propane.  In developed countries charcoal is a luxury fuel, and it would be “absurd” for people in developed countries to all of a sudden switch to heating our homes with it.  There in lies the problem: biochar is viable on the market as both an agricultural tool and as a fuel in developing countries.

The best strategy then, according to Shackley, is to find sustainable feed stocks.  He gives an example, “if you’ve got a rice paddy system… the rice husks are thrown into the paddy field and they decompose for methane, which is a very powerful greenhouse gas. So in that case, it’s much more efficient to put the rice husk into a pyrolysis or gasification machine, carbonize it, and put that into the field and you’re returning the nutrients to the soil.” And then you get a carbon negative process.  Depending on the machine, the pyrolysis process itself can produce energy that can be used as well.

Sounds great, right?  In principle, sure.

Few problems:

In terms of accounting biochar is only carbon neutral or negative if the biochar is replanted into the soil right away and not used as a fuel.  More likely is that it is stored. Shackley says that common practice is not to count pyrolysis process in the CO2 footprint.  Pyrolysis does produce CO2.  And if the biochar isn’t planted but used as a fuel then it is carbon positive. Sure it emits less carbon than fossil fuels, but using it as a fuel would distort its price as an agricultural input.

This leads to the second problem: logistics.  Shackley describes the process, “You’ve got a lot of movement of material: you’ve got to grow it somewhere, you’ve got to use quite a lot of land to grow it, you’ve got to move it [left over wastes], you’ve got to store it, you’ve got to process it, you’ve then got to store the biochar before it goes onto the field.  And if you’re talking about very large volumes, you’ve got to store it somewhere.”

In biochar manufacture and use there is a temporal delay: Shackley says often the feedstock waste from agriculture will come from the end of a harvest, but the most useful time to use it would likely be the following spring or summer.  Logistics are a huge part of the process but those details are often glossed over.

Only loosely mentioned is a third problem: no one is entirely certain of the optimum composition of biochar for maximum temporal carbon sequestration. An article about biochar on MNN mentions in passing, “Plowing biochar into soil sequesters the carbon for a long time — biochar fields have been found in South America dating back thousands of years and still full of their carbon solids.” A long time sure, but it depends on what it’s made of.**  Scientists may be able to test terra preta to see what it’s been made of in the past, but other materials will be used to create modern biochar.

So why not only make biochar from certain specific materials?  Simplistically: Soil contains bacteria and mineral nutrients that help plants grow.  Biochar contains minerals as well that are beneficial to plant growth, which makes it beneficial as a fertilizer.  Different biochar compositions could provide optimum minerals depending on the soil composition.  It’s common sense that in order to be sustainable, biochar be composed of native organic materials. So, wherever it’s used its make up will vary.

Biochar can be made of almost any material and some materials, according to Dr. Saran Sohi, a soil specialist at the UK Biochar Research Institute, are more stable than others.  Stability determines how long carbon will be trapped (sequestered) in the soil.  There’s not yet been enough research to determine how long certain materials will sequester carbon.

“When you pyrolyze material you end up with a complex substance. And some of that is volatile,”  explains Shackley. Any biochar used as an agricultural fertilizer (carbon sink) will have to be stable for well over 100 years,  “Ideally we want to keep 75-80% of carbon in a stable form for hundreds of years.  If it all comes out as CO2 after 100 years, in my view, it isn’t worth it…. Because if we haven’t solved the problem, and it all comes out again in 100 years time …you could get billions of tonnes of carbon dioxide back in the atmosphere and we might be having a severe climate crisis and it could be disastrous.”

Forth, the market model is uncertain on several levels:  Sohi says that more research must be done on biochar composition so that the benefits to farmers (i.e. increased crop yield) can be clearly enumerated.  Until then a market price for biochar as a fertilizer will be hard to pin down. It will also be difficult to displace traditional chemical fertilizers with this “natural” alternative, where the added yields are certain. Any market in developing countries where charcoal is used as a fuel (even as a low-carbon alternative) and an agricultural input must be heavily regulated: in order that charcoal remains cheap enough to be used as a low cost agricultural input, to prevent people trading the biochar at profit to be used as fertilizer (rather then fuel too), then from turning to another fuel that might degrade the environment.

After years of colossal f-ups, the development community has to come to an agreement that aid must be nuanced– that is, designed specific to the environment in which it’s implemented.  The financial crisis(es) have shown us that we need heavy market regulation, not just of financial markets but commodities as well.  In order to address climate change we need to use all of the technology at our disposal, which includes biochar.  But unless we take our time, and correctly implement its use, biochar could do more harm than good. The US’s biochar bill might be something to be weary of. Shackley points out that such a bill will drive more investment into research and make certain that regulators ask the right questions about safety and benefits.  On the other hand, history has shown that governments dolling out money must be monitored to make certain processes are safe.  More research must be done on biochar, its use should not be rushed into, and the market must be heavily regulated.

* Dr. Paulo dos Santos, SOAS.

**For example manure, palm tree litter are more volatile.

Ann Danylkiw is a freelance new media journalist specializing in green economics and finance. She is completing an MSc in Finance and Development Economics at SOAS in London. A small but fierce personality, her latest obsessions include spicy hot chocolate, vegan pumpkin pie, graphic novels, and Indonesia.  She will be covering Cop15 for a coalition of blogs including solveclimate.com, where she is a regular contributor.

Article re-published with permission.

Whether for enhancing crop yields by improving soils (increased nutrient/cation availability and water-retention ability making them ideal for use in agricultural soils) , or storing massive amounts of carbon in the soil, biochar is creating its own energy wave right now.  If you’d like to see how the company re:char make biochar check out this short video. It demonstrates a small scale analytical pyrolyzer turning wood waste into biochar and bio-oil.

“There is one way we could save ourselves, and that is through the massive burial of charcoal” James Lovelock

Converting biomass into charcoal type char which can be used to improve soil fertility, while also trapping carbon dioxide, certainly has major attractions. Some energy is generated too. But a key issue is whether, in net climate terms, the loss of (some) biomass for direct conversion to energy is balanced by the gain from CO2 entrapment and extra CO2 absorption by more fertile soils- especially if the combustion route also used geo-sequestration i.e. CCS?

A parametric study of bio-sequestration by Malcolm Fowles at the Open University, suggested that from a global warming perspective we should displace coal with biomass if the latter’s conversion efficiency is much over 30%. Otherwise we should sequester carbon from biomass rather than generate energy.

However, this was only a preliminary study and he felt that a more comprehensive analysis might shift the balance more towards bio- sequestration. He did not include carbon savings from hydrogen and other pyrolysis products, or crucially from reduced soil emissions- that’s hard to assess after all. And costs were not included in his model, although qualitatively and intuitively he felt bio-sequestration should be cheaper than geo-sequestration by CO2 capture and storage. (Fowles, M. (2007), “Black carbon sequestration as an alternative to bio-energy’, Biomass and Bioenergy 31: 426-432, doi:10.1016/j.biombioe.2007.01.012)

Clearly though there are lot of unknowns- for example as to the permanence of bio-sequestration – how long will the carbon stay trapped in the soil? Some say thousand of years, based on historical examples of charcoal use. But then that was in traditional ‘no til’ agricultural contexts: farming methods would now have to change if we wanted to avoid releasing the stored carbon.

There are also strong views about the likely impact if biochar production was adopted on a wide scale. While some see it as a major way to deal with climate problems, the fear of vast agri-business plantations worries some people, Guardian correspondent George Monbiot especially, although even he accepts that there could be niche uses. http://www.guardian.co.uk/environment/2009/mar/24/george-monbiot-climate-change-biochar

Biochar can be produced by pyrolysis at around 500 degrees C, either slowly (over days, the traditional approach e.g. in kilns), which results in about equal amounts of biochar (about 35% of the original biomass), liquid and gaseous fuels; or rapidly (e.g. flash pyrolysis, in seconds), which gives less biochar (about 15% converted) less gaseous products, but more liquid ‘bio-oil’ products (about 75%). In addition there is high temperature (800C) gasification, which typically, over hours, yields a low proportion of solids (only about 10% biochar), but a high proportion of gaseous products (about 85%).

Clearly with fast pyrolysis or gassifiation the processing throughputs can be larger, but slow pyrolysis gives you more biochar in the mix. For example, BEST Energy in Australia, have developed a slow pyrolysis approach called Argichar, in which between 25 and 70 % by weight of the dry feed material is converted to a high-carbon char material, while also generating syngas: see www.ecovoice.com.au/enews/enews-47/Images%2047/Brief%20BEST%20pyrolysis%20and%20Agrichar%202007.pdf

Potential

How much carbon sequestration might be achieved? Globally, according to Professor Tim Lenton, from UEA, “Biochar has the potential to sequester almost 400 billion tonnes of carbon by 2100 and to lower atmospheric carbon dioxide concentrations by 37 parts per million.” How does that compare to other approaches, like Carbon Capture and Storage? Biochar production removes CO2 from the air, while CCS aims to remove it from the exhaust gases of power plants- in large quantities. According to Bruce Tofield, from the Low Carbon Innovation Centre, UEA ‘In the UK biochar might yield a few million tonnes CO2 saving with current biomass sources – CCS needs to aim for over 100 m tonnes’.

However, that doesn’t mean turning biomass into biochar is a bad idea, and some environmenalists are quite enthusiastic. In ‘The Renewable World’, a new book from the World Future Council, Herbie Girardet and Miguel Mendonca (Green Books) are very keen on techniques for improving soil fertility and biological carbon dioxide absorption, and talk of ‘carbon farming’. They note that ‘by pyrolysing one tonne of organic material which contains about half a tonne of carbon, about half a tonne of CO2 can be removed from the atmosphere and stored in the soil, while the other half can be used as carbon neutral fuel.’ However they add that ‘a major question that needs an urgent answer is how enough organic matter can be made available to produce significant amounts of biochar. Opponents argue that farming communities in developing countries may be forced to produce fast-growing tree monocultures on precious agricultural land to produce biochar to counter climate change for which they are not even responsible’. But they point to sewage as an example of a less contentious feedstock.

There are no doubt many other niche sources of biomass like this, as well as novel sources like algae, although there may also be competing uses -e.g. sewage gas is one of the cheapest renewable energy sources for electricity generation. But then we are back with the question of which is most effective at reducing carbon dioxide?

The Royal Society’s recent review of Geoengineering commented ‘It remains questionable whether pyrolysing the biomass and burying the char has a greater impact on atmospheric greenhouse gas levels than simply burning the biomass in a power plant and displacing carbon-intensive coal plants’. It concludes ‘biomass for sequestration could be a signi?cant small-scale contributor to a geoengineering approach to enhancing the global terrestrial carbon sink, and it could, under the right circumstances, also be a benign agricultural practice. However, unless the sustainable sequestration rate exceeds around 1 GtC/yr, it is unlikely that it could make a large contribution. As is the case with biofuels, there is also the signi?cant risk that inappropriately applied incentives to encourage biochar might increase the cost and reduce the availability of food crops, if growing biomass feedstocks becomes more pro?table than growing food’.

That is a point picked up by James Bruges in the new Schumacher society report ‘The Biochar Debate’ (Green Books). He argues for a global Carbon Maintenance Fund, rather than just awarding carbon credits. But that is rather going ahead of ourselves. First we have to see if the biochar option makes sense. The Royal Society pointed out that so far there was not enough research on the topic. Defra has commissioned the UK Biochar Research Centre (UKBRC) to review the impacts of biochar. Hopefully that will provide some answers.

More at http://www.biochar-international.org/

The biochar process is carbon negative: it removes net carbon from the atmosphere. When a green plant grows it takes CO2 out of the air to build its body. All of the carbon in the plant came from CO2 taken out of the air, and returns to the air when the plant dies and decomposes.

When the biomass is pyrolyzed heated in the absence of oxygen it produces charcoal, which is called biochar when buried in the ground. Over 40% of the total carbon from the waste biomass is retained in biochar and permanently sequestered in the soil, effectively removing that carbon from the atmosphere. The carbon in a ton of biochar is equivalent to 3 to 3.6 tons of CO2.

Biochar is not only a carbon sink, it increases soil fertility increasing cat-ion exchange and water retention capacity in soils, while reducing nutrient leaching and providing a “coral reef” for soil microorganisms thereby significantly increasing productivity and crop yield.

Biochar research was first inspired by the discovery of Terra Preta or black earth soils in the Amazon Basin, where an ancient civilization buried charcoal, transforming otherwise barren tropical soil into Terra Preta soils that are still incredibly fertile today.

How is Biochar made?
A machine like the Biochar 1000 by Biochar Systems is a small commercial biochar production unit made in the US. At only 12 feet long and 4000 pounds it can easily be moved on a two axel trailer towed by a pickup. Biomass is pyrolised in  a low oxygen environment and the result is Biochar when applied to the soil. Ecopreneur will be following this company and others as the momentum for Biochar increases.