The Potential of Green Charcoal

Reader Contribution by Staff

About Green Charcoal

Founded in Brazil in 1986, Pro-Natura was one of the first Nongovernmental Organizations from the South to internationalize. After the Rio Summit in 1992, Pro-Natura International was born, with its headquarters in Paris. More than 400 high-level volunteers are mobilized in programs in the global South, bringing together the fight against poverty with biodiversity conservation and the mobilization against climate change.

Two billion people must face the problem of domestic energy needs that pushes them to deforestation, adding to the problems of drought and desertification. To fight this, Pro-Natura invented and developed the innovative technology of “green charcoal.” This technology proves to be very competitive in relation to wood charcoal, has a positive effect in terms of climate change, and, in recognition of this, received the first place prize for technological innovation from the Altran Foundation in 2002.

In Africa, Latin America and Asia — including India and China — wood is becoming harder to find and, in general, alternative energies are not available or affordable for households. Two billion people across the world therefore depend on wood-generating deforestation for their domestic energy needs (particularly in Africa, where it represents 89% of energy sources). This use of unsustainable wood is a major cause of deforestation, which poses a serious ecological risk. Deforestation accentuates drought, desertification and climate change. The exclusive use of wood as a domestic fuel presents numerous other major disadvantages:

• As deforestation progresses, the burden on women and children mounts: They must travel longer and longer distances to supply themselves with the wood and other forest products they need. This additional obligation diminishes the time they could dedicate to other tasks such as education, which are nonetheless indispensable. In the Sahel for example, women must, at times, travel 20 kilometers a day to find the wood necessary to cook their food.

• With less fuel available, the quantity and quality of food diminish.

• Supplying the necessary fuel energy demands an increasingly large proportion of revenues.

• Finally, smoke released is harmful to the eyes and lungs. The World Health Organization estimates that 1.6 million women and children die prematurely because of wood smoke in poorly ventilated homes.

Taken together, the serious constraints of wood use by these populations reduce the possibilities for improving living conditions and impede economic progress.

In 2002, Pro-Natura won the Altran Foundation’s first prize for technological innovation for the ecological production of biochar. The method employed here involves unused agricultural residues or renewable biomass which would otherwise go to waste, and transforming them into briquettes of green charcoal, a wood charcoal substitute. Pro-Natura thus proposes an alternative domestic fuel made of vegetable carbon, obtained through a proven, clean and efficient process, based on the continuous carbonization of renewable biomass. Savannah weeds, reeds, wheat or rice straw, cotton and corn stems, rice or coffee husk, and bamboo can all be used to produce green charcoal. Any form of wood, including sawdust, can also be carbonized, with a yield around three times higher than would be the case using classical batch processes. A special machine allows for the economical and ecological production of between 4 and 5 tons of green charcoal per day. The first Frenchmade machine has been in use in the Saint-Louis region of Senegal since 2008.

Carbonization of biomass is made in a continuous manner. It relates to a continuous carbonization of vegetable matter, followed by an agglomeration into briquettes or bars. This technology is based on the use of a retort heated to 550 degrees Celsius, in which the biomass flows continuously in the absence of oxygen. The temperature of the retort is maintained constant with the combustion of the pyrolysis gases that are recycled and burned in a second post-combustion chamber, thus avoiding the release of greenhouse gases in the atmosphere.

One of the originalities of the process is that once the machine is preheated, the process produces its own energy — except for the transfer of the biomass, which is done with a small, low-energy consumption electric motor. This process is therefore practically autonomous in terms of energy, and its yield (weight in green charcoal in relation to weight of the biomass at less than 15 percent moisture) reaches 30 to 45 percent according to the type of biomass. In addition to the advantages of the carbonization process in the retort, the cost of running the reactor is lowered by the continuous production, thus avoiding stopping the machine each time to recuperate the charcoal.

Increase Agricultural Productivity and Fight Climate Change

The fertilization of the soil by green charcoal is an ancestral practice initiated more than 7,000 years ago by pre-Columbian Indians in the Amazonian regions. According to the most recent studies, these enrichments applied by the Indians on their fields consisted principally in a mixture of carbonized matters (such as wood charcoal, called biochar or agrichar in this context) and organic waste, which led to the formation of a particular soil of a deep color and of remarkable fertility (the “Terra Preta”).

The properties of these soils were conserved until today and discovered recently by the scientific community, which accords it a strongly increasing interest. Recent research shows that the great fertility of the Terra Preta has resulted principally from the presence of numerous carbonized particles that act as a “nest” facilitating the fixation of water and nutrients and the development of a rich population of microorganisms in the soil responsible for the improved growth and resistance of the plants that grow there. This also explains why optimal fertility is in fact obtained in combining enrichment by biochar with a complementary traditional fertilization (compost, manure), bringing the essential microelements to “nest” there.

If the exact duration of retention of the carbon by the Terra Preta still remains clouded in mystery, the soils discovered prove that this longevity can easily reach several thousands of years, which permit us to consider this as a real “carbon sink” capable of offering an effective, clean and sustainable solution to climate change by absorbing and stocking the excess CO2 from the atmosphere as carbon. Biochar is made largely of carbon, which the crops or trees previously sucked out of the air in the form of CO2. Unlike crop wastes and wood, it’s an extremely stable substance, which, if mixed into soil, will safely lock up its carbon content for hundreds or even thousands of years — a biological form of carbon capture and storage.

With this “win-win” strategy, it is thus possible to render the carbon footprint globally negative (by taking more carbon from the atmosphere than is emitted), while fighting effectively against poverty and hunger by the sustainable and lower cost increase of productivity of the land and the reduction of the dependence on traditional, expensive and polluting chemical fertilizers.