Dubbed biochar, the material is produced by heating cocoa shells to 600 degrees Celsius in an oxygen-free chamber.
The process traps greenhouse gases and the end product can be used as fertilizer or to produce “green” concrete.
While the field of biochar manufacturing is still in its infancy, the technology offers an innovative way to remove carbon from the atmosphere, experts say.
The UN’s Intergovernmental Panel on Climate Change says biochar could be used to capture 2.6 billion of the 40 billion tonnes of carbon dioxide humans produce each year.
However, expanding the use of this substance remains difficult.
Amazon
“We are reversing the carbon cycle,” Circular Carbon CEO Beck Stenlund told AFP from a biochar plant in Hamburg.
The factory, one of the largest in Europe, receives used cocoa shells from a nearby chocolate factory through a network of gray pipes.
Biochar traps carbon dioxide in the peels, a process that could be used for any other plant.
If cocoa husks were destroyed as usual, their decomposition would release carbon into the atmosphere.
Instead, the carbon is trapped in the biochar for centuries, according to David Oppen, an ecologist at the Uni-la-Salle Institute in France.
He told AFP that one ton of biochar stores “the equivalent of 2.5 to 3 tons of carbon dioxide”.
Biochar was once used as fertilizer by indigenous peoples in the Americas before being rediscovered in the 20th century by scientists searching for fertile land in the Amazon basin.
The amazing spongy texture of the material increases crop yields by increasing the uptake of water and nutrients from the soil.
The Hamburg factory is surrounded by the smell of chocolate and warmed by the heat of the pipes.
The final product is put in white bags to be sold to local farmers in the form of pellets.
Farmer Silvio Schmidt, 45, who produces potatoes near Bremen, west of Hamburg, hopes the biochar will help “deliver more nutrients and water” to his sandy soil.
carbon cost
The production process, called pyrolysis, generates a certain amount of biogas, which is sold to a nearby plant. In total, the plant annually produces 3,500 tons of biochar and “up to 20 megawatt hours” of gas from 10,000 tons of cocoa shells.
However, the production method is still difficult to bring to the level desired by the Intergovernmental Panel on Climate Change.
“To ensure the system is storing more carbon than it is producing, everything has to be done locally with little or no travel, otherwise the whole process is pointless,” says Oppen.
Not all soils are well suited for biochar. Oppen points out that compost “is most effective in tropical climates”, while the raw materials for its production are not available in all regions.
He points out that the cost can be exorbitant, as it amounts to “about $1,070 per ton, which is a high price for farmers”.
In order to make better use of black powder, Oppen insists on the need to find other uses for it, such as using it in the construction sector for example, to produce “environmentally friendly” concrete.
In order to make a profit, the biochar producer came up with the idea of selling carbon certificates to companies looking to balance their carbon emissions by producing a certain amount of biochar.
With biochar included in Europe’s highly regulated carbon certification scheme, “the industry is growing exponentially,” says Stenlund. His company looks forward to opening three new sites to produce additional quantities of biochar in the coming months.
Projects related to the production of biochar are multiplying across Europe. According to the Biochar Production Association, production is expected to almost double to 90,000 tons this year compared to 2022.
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