Biochar is a high-carbon, fine-grained residue that is produced via pyrolysis. Image by K.salo.85 – Own work, CC BY-SA 4.0
Cocoa shells – residual material from cocoa production – provide an opportunity for recycling materials and reducing carbon emissions. The combined advantages of biochar for the farmer include using less fertiliser, creating conditions for improved humus formation and assisting with the production of higher crop yields.
A new factory has opened for this purpose. Called Circular Carbon, the factory produces biochar from cocoa shells for use in horticulture and agriculture. Biochar is the lightweight black residue, formed from carbon and ashes.
The company Circular Carbon GmbH operates the first industrial plant for the production of biochar at its base in Hamburg, Germany. Here, the company carbonises nutrient-rich cocoa shells by pyrolysis. This is a decomposition reaction in which organic materials break down in the absence of oxygen. Other organic materials, such as oat husks, straw or green waste, are equally suited for the pyrolysis process.
The official definition of biochar is “the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment”. Biochar is a stable solid that is rich in pyrogenic carbon and can endure in soil for thousands of years.
With its popularity in agriculture, when it is added to the soil biochar can sequester (‘remove or separate’) the carbon it contains and thereby act as a carbon sink (a carbon sink is anything that absorbs more carbon from the atmosphere than it releases).
The material can also be used in flood management to turn a city threatened by flooding into a “sponge city”. Here, the biochar can absorb excess water from heavy rainfall and release it back to urban trees in times of heat stress and drought.
Another application is with animal farming. With this use, biochar can increase feed efficiency and residual plant digestibility. This can lead to higher milk yield, better weight gain, higher quality of animal products such as a higher protein contents in milk or meat.
The Intergovernmental Panel on Climate Change, the IPCC, has recognised biochar as a method of carbon dioxide sequestration: “Biochar is an important carbon removal technology with several co-benefits to fight climate change”, according to an IPCC report.
There are considerable advantages of using biochar in agriculture from both a chemical and biological point of view: biochar increases the cation exchange, the balance of nutrients and bases is supported, humus formation is improved, the nutrients potassium and phosphorus are mobilised, and the nitrogen balance becomes more sustainable, which leads to a reduction of industrial fertilisers use.
In addition, biochar can increases the pore volume of the soil and counteracts soil compaction it also improved the water retention capacity and the air balance in the soil.
Dr. Tim Sandle is Digital Journal’s Editor-at-Large for science news.
Tim specializes in science, technology, environmental, and health journalism. He is additionally a practising microbiologist; and an author. He is also interested in history, politics and current affairs.