Biochar 101

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By Avril David

What is Biochar?

Thousands of years ago, South Americans of the Amazon Basin began using charred animal waste and wood to make what the Portuguese called “terra preta” (black earth).  The terra preta soil they created remains fertile for thousands of years without the use of any fertilizer, thereby increasing agricultural yields and further reducing harmful emissions caused by inefficient farming practices and/or the use of chemical fertilizers.

Today, we call this “biochar” – a highly porous charcoal made from any form of organic waste – ranging from forest to manure – through a process known as pyrolysis, which is when biomass is burned at 400-550 degrees, without oxygen.

Due to its high carbon content and porous nature, biochar can help soil retain water and nutrients (it releases them very slowly over time), protect soil microbes and ultimately increase crop yields in addition to acting as natural carbon sink by sequestering CO2 and storing it in the soil. A World Watch report on Mitigating Climate Change through Food and Land Use estimates that if “biochar additions were applied on just 10 percent of the world’s cropland (160 million hectares), the method could store 29 billion tons of carbon dioxide equivalent, offsetting nearly all the emissions from fossil fuel burning”. According to the report, “initial analyses suggest that planting vegetation for biochar on idle and degraded lands could be quite economical and is thus a promising option for carbon offset payments”. 

The Science

Biochar essentially stabilizes soil, thereby allowing it to absorb and store more carbon and enhance its role as a carbon sink. Left undisturbed or protected, soil serves as a vital carbon sink for the Earth.  This function often breaks down, however, when soil is disturbed.  Then, it can quickly change from carbon sink to major source of CO2 emissions.That’s why burying biochar in the soil can improve it’s carbon sequestration potential just as conservation tilling and grass-planting do. Research from the Illinois Sustainable Technology Center states that “the overall natural (carbon) cycle is carbon neutral. In contrast, pyrolysis can lock up this atmospheric carbon as biochar for long periods (e.g., centurial or even millennial time scales)”, which essentially has a carbon negative effect.

In terms of added agricultural and environmental benefits, the International Biochar Initiative states that,“char-amended soils have shown 50 - 80 percent reductions in nitrous oxide emissions and reduced runoff of phosphorus into surface waters and leaching of nitrogen into groundwater.  As a soil amendment, biochar significantly increases the efficiency of and reduces the need for traditional chemical fertilizers, while greatly enhancing crop yields.” In addition, the process used to make biochar (pyrolysis) has useful by-products such as gases that can be converted into electricty, gasoline or industrial chemicals.

Issues and Concerns

During recent climate negotiations in Bonn, Germany, participants of a side event on biochar noted uncertainty around biochar’s ability to sequester carbon, the possibility that biochar might stimulate soil microbes that turn soil carbon into carbon dioxide, and the potential albedo (or reflective) effect of laying charcoal near the soil surface.

Participants also noted that biochar could have multiple unintended social and eco-side effects, for instance, biochar production could lead to the development of biochar plantations that take the place of forests. Negative impacts of plantations can include: appropriation of land from local communities, loss of rural job opportunities, loss of biodiversity, and soil degradation.

Furthermore, as stated by The Guardian UK's George Monbiot, “in some cases charcoal in the soil improves plant growth, in others it suppresses it…in some cases charcoal stimulates bacterial growth, causing carbon emissions from soils to rise.” Not to mention the fact that the process of pyrolosis itself can also be a source of harmful emissions if the gases emitted are not properly managed. 

Pilot Projects

While biochar certainly has potential as a climate change mitigation tool in theory, continued research is needed to ensure that it is in fact viable in various soil types and that the potential adverse effects do not outweigh its benefits. To that end, biochar pilot projects are currently underway in multiple countries.  For instance, at the University of Tarapacá in Chile, researchers are conducting a comprehensive pilot program that utilizes a lab-based pyrolysis unit that produces biochar. The researchers plan to study both availability and applicability of local feedstocks for biochar and will evaluate which feedstocks are the most efficient in producing biochar. After the initial phase, the project will be scaled up to increasingly larger farms with larger units and feedstocks.  While the University of Tarapaca’ s project will likely yield some important findings for the further development and use of biochar as a carbon sequestration and soil enhancement tool, other biochar projects are focusing on the substance’s ability to supplement existing conservation efforts. For instance, in Cameroon, a project sponsored by the Biochar Fund in Belgium plans to use biochar as a “buffer” to protect pristine rainforests threatened by slash-and-burn farming and increasing populations.  The biochar could enable farmers to produce greater yields on existing agricultural lands rather than using the rainforest as a source for new land.

Country Level Initiatives

For a list of 9 country projects

Australia: Turnbull Puts Biochar Front and Center
The leader of the Australian Opposition party, Malcolm Turnbull, has voiced strong support for the inclusion of biochar in an international climate treay and has confirmed that economic incentives for biochar will be central to his negotiations with the Rudd Government on the development of Australia’s emission trading scheme.

Australia: Biochar receives a $1.4-million funding boost from Govt
In May 2009, the Australian Government committed $1.4m in funding for the development of biochar.

DRC: Protect rainforests in Congo
The Congo Basin Forest Fund is an initiative by the British and Norwegian governments, aimed at protecting the unique tropical rain forests of Central Africa and their biodiversity and ecosystem services. The fund recently awarded funding to Belgium’s Biochar Fund and its Congolese partner ADAPEL to implement its biochar concept in 10 villages in the Equateur Province of the Democratic Republic of Congo. The Biochar Fund says the scheme will help address lack of access to clean, renewable energy among poor rural communities while simultaneously cutting emissions from deforestation and forest degradation. Read articles describing the project here:
Congo biochar initiative will reduce poverty, protect forests, slow climate change

For more information on biochar, access the following reports and news stories that were used in this article here:

UNFCCC Copenhagen Draft negotiating text section on biochar

Carbon: The Biochar Solution, TIME

Debating the Climate Benefits of Biochar, New York Times

Can biochar help save the planet?, CNN

Biochar: one way to deal with more fire-prone forests, New York Times

Burn, bury and bargain with it: biochar ticks the green boxes, Sydney Morning Herald

Farming for Nine Billion People, New York Times

Agriculture: A necessary complication in the climate negotiations, Grist

The Consensus Before the Consensus, Policy

How to Save the Amazon Rainforest
Payments for Ecosystem Services: Download the Primer

Avril David conducts research on the terrestrial carbon sector for Ecosystem Marketplace's Forest Carbon Portal.