Pro-Natura International (PNI)

Green charcoal

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Biomass energy or green charcoal

Pro-Natura's solution: the Pyro machine and its green charcoal

The technology: a continuous carbonisation of renewable biomass

Agglomeration in charcoal briquettes

Potential in the fight against climate change

Biochar

Biomass energy or green charcoal

The access to energy, which is increasingly considered a fundamental right, is a necessary condition for all processes of development. In Africa, Latin America and Asia - including India and China - wood is becoming harder to find and in general alternative energies do not exist. 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, which are nonetheless indispensable. In the Sahel for example, women must at times travel 20 kilometres 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 WHO 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 their living conditions and impede economic progress.
Pyro

Pro-Natura's solution: the Pyro machine and its green charcoal

Pyro
The solution consists in recuperating agricultural residues or renewable biomass that cannot be otherwise valorised and transforming them into briquettes of green charcoal that can be used in the same way as wood charcoal. With this procedure, Pro-Natura proposes a domestic fuel made of vegetable charcoal, obtained with a carbonisation process, the effectiveness of which has been proved.

This process is based on the continuous carbonisation of renewable biomass. Savannah weeds, reeds, straw of wheat or rice, cotton and corn stems, rice or coffee husk and bamboo can all be used to produce green charcoal. Wood can also be carbonised in any shape, even as sawdust with a yield around 3 times higher than using classical batch processes.

Each Pyro-7 machine allows the economical and ecological production of between 4 and 5 tons of green charcoal per day. The first machine made in France has been in use in Senegal in the Saint-Louis region since the end of 2007 (see photo above). In partnership with Areva, the technology was transferred to South Africa to the Necsa Company who has a production license for the southern cone of Africa.

The technology: a continuous carbonisation of renewable biomass

The process is based on the continuous carbonisation of vegetable matter, by agglomerating the charcoal thus obtained into nuts, briquettes or bars. The trials previously done to carbonise the biomass in a batch process by entire sheaves failed due to mechanical problems and poor energy efficiency.

This technology is based on the use of a retort heated to 550°C 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.

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 15% moisture) reaches 30-45% according to the type of biomass.

Agglomeration in charcoal briquettes

Green charcoal in cook stove
After carbonisation, an agglomeration of these charcoal fines is necessary to facilitate the combustion and transport of the briquettes obtained. The fabrication of briquettes is performed by compression and requires a binder to mix with the charcoal fines. This binder can either be starch, Arabic gum, molasses or clay, depending of the availability and cost. The percentage varies from 10 to 20% in the case of clay. The wet briquettes next pass into a dryer to eliminate the water, in such a way that they are sufficiently solid to be used in domestic ovens and cooking devices.

Potential in the fight against climate change

agroforesterie

Besides the direct advantages for the local population, the installation of a Pyro-7 machine presents several advantages for the environment that may be summarized into three sources of GHG emission reductions compared to the baseline situation:

Prevention of deforestation that would have resulted from the production of wood charcoal or from the collection of fuelwood replaced by green charcoal (produced from renewable biomass) in the project activity;

Prevention of CH4 emissions from traditional wood charcoal production. The efficient carbonization performed by the Pyro-7 machine avoids any emission of greenhouse gas (GHG): instead of being released in the atmosphere, the pyrolytic gas produced in the reactor is recycled and helps maintaining the carbonization process. On the contrary, inefficient traditional methods for charcoal production such as earth mound kilns emit in particular a lot of methane, a GHG very harmful for the environment.;

Reductions of CO2, CH4 and N2O emissions from the lack of combustion of agricultural residues.

In order to quantify these reductions within the project boundary, i.e. the geographical area affected by the project, the value of several contextual parameters such as the existence and importance of deforestation practices or the main energy sources used by households have to be determined. In our case, the project boundary corresponds to the region in which the green charcoal is produced by the Pyro-7, distributed and consumed.

Estimation of emission reductions is based on the corresponding following hypotheses:

Deforestation prevented per ton of wood charcoal not made: 5.5 tons of dry wood, corresponding to a conservative number chosen by the Carbon Fund of the World Bank;

Emissions of CH4 prevented per ton of wood charcoal not produced: 3.5 t CO2 -equivalent. This value is an average between the emissions of the least sophisticated traditional carbonisation techniques of the Sahel (which are common in the base scenario) and the value used for the Plantar project, in which sophisticated ovens are used;

Brush burning of unused biomass avoided: permits reduction of 0.06 kg of CO2-equivalent per ton of biomass used in the production of green charcoal.

To date, there is no CDM Methodology approved by the UNFCCC. However, Pro-Natura proposes to develop a new methodology that would render the project eligible as a small-scale operation.

Pro-Natura already follows the prescriptions of Annex B relative to the simplified procedural modalities of small-scale CDM projects. Specifically, it conforms to Paragraph 19: "For renewable energy technologies that are replacing sources of non renewable biomass, the simplified baseline is the consumption of sources of non renewable biomass multiplied by an emission ration corresponding to the sources of non renewable biomass replaced”.

The calculation evaluating carbon credits generated by one Pyro-7 machine result in: 11.6 tons of CO2-equivalent per ton of green charcoal. We are pleased to announce that Air France, through the intermediary Action Carbone of GoodPlanet, is now giving its passengers the option to compensate their CO2 emissions with carbon credits generated primarily by the Pro-Natura green charcoal project in Senegal.

For more information, visit www.actioncarbone.org.