In a brickyard in the German port city of Hamburg, cocoa bean shells are processed into a black powder that stores carbon and helps combat climate change.
A material called biochar is produced by heating tiles to 600ºC in an oxygen-free chamber.
This process captures greenhouse gases and the end product can be used as compost or as a raw material in making „green” concrete.
Although still an emerging industry, the technology offers a new solution to removing carbon from Earth’s atmosphere, experts say.
According to the United Nations Intergovernmental Panel on Climate Change (IPCC), biochar has the potential to capture 2.6 billion of the 40 billion tons of CO2 currently produced by humanity each year.
But bringing its use to scale remains a challenge.
– Formerly used in the US –
„We are reversing the carbon cycle,” Beik Stenlund, chief executive of biochar maker Circular Carbon, tells AFP from the Hamburg factory.
The plant, one of Europe’s largest, receives cocoa bean husks from a nearby chocolate factory through a network of ash pipes.
Biochar captures the CO2 in the husks, but the same process can be used for any other plant.
If used cocoa is disposed of without this treatment, the carbon in it is released into the atmosphere during the decomposition of the product.
Instead, with this method, carbon is captured in biochar for „centuries,” says environmental scientist David Houbon of France’s UniLaSalle Institute.
Huben tells AFP that one ton of biochar can save „2.5 or 3 tons of CO2 equivalent”.
This material was already used as a fertilizer by indigenous peoples of the Americas, and was rediscovered in the 20th century by scientists exploring the extremely fertile soils of the Amazon basin.
Biochar’s amazing spongy texture increases harvest by increasing water and nutrient absorption from the soil.
In Hamburg, the factory is surrounded by the aroma of chocolate and the heat emanating from the installation’s network of pipes.
The final product is poured into white sacks and sold in pellet form to local farmers.
One of them is Silvio Schmidt, who grows potatoes near Bremen, west of Hamburg. The 45-year-old farmer believes biochar will „bring more nutrients and water” to his sandy land.
– Everything should be local –
This process, known as pyrolysis, produces a certain amount of biogas, which is resold to a nearby factory.
In total, the plant produces 3,500 tons of biochar and „up to 20 megawatt hours” of gas from 10,000 tons of cocoa shells each year.
But bringing the production system to the level envisioned by the IPCC is difficult.
„To ensure that the system captures more carbon than it produces, everything has to be done locally, with little or no transport. Otherwise it’s pointless,” says researcher Huben.
Also, he adds, not all soil types are well-suited for biochar, which is „more useful in tropical climates,” and the raw material for its production is not available everywhere.
„It costs about 1,000 euros ($1,070) per ton, which is too much for a farmer,” says the scientist.
To make better use of this black powder, new uses must be found, emphasizes Huben, pointing to the construction.
For example, biochar could be used to make „green” concrete, he says.
The industry has floated another idea to reap the benefits: selling carbon certificates to companies that want to balance their emissions balance by producing a certain amount of biochar.
By adding the material to the European Union’s highly regulated system of carbon certificates, „we see strong growth in the sector,” says Stenlund, the factory’s CEO.
His company plans to open three new facilities to produce more biochar in the coming months.
Across Europe, biochar projects are proliferating. Production will nearly double to 90,000 tonnes between 2022 and 2023, according to the industry’s federation.