Summary

Since 2024, atmosfair and the Tanzanian company Dark Earth Carbon (DEC) produce biochar in a large pyrolysis plant in the heart of timber production in Tanzania, Iringa, and use it as fertiliser on Tanzanian farmland. The use of biochar permanently stores CO2, while at the same time adding valuable nutrients to the soil.

As a raw material, we use wood waste from forest management and small wood processing companies. Before the project started, the wood residues were piled up in high heaps, which were either burnt openly or left in the forest and posed a major risk for the spread of forest fires. With the project, we are now changing this and utilising at least part of the seemingly endless biomass residues. The local forestry authorities are therefore also very much in favour of the project, as it reduces the risk of forest fires.

Social factors play a major role here. We obtain a large proportion of the required pruning residues from small forest owners and thus strengthen the local economy. The microforest owners own forest plots of less than one hectare and earn extra money by selling the wood, but their main income comes from other activities. DEC employees travel directly to the villages and buy the pruning residues there and chop them in a mobile plant. Another challenge – it is not for nothing that there are hardly any logistics in the remote areas. A lot of work is required to make it possible to buy the waste there in an organisationally and economically viable way. But that’s not all: atmosfair and DEC also offer training courses on biodiversity for small forest owners. In these training courses, we emphasise the resilience of biodiverse areas and remind them of native tree varieties that are well suited to the timber industry.

When all the lorries with the wood cuttings have arrived at the factory, they are charred into biochar in the pyrolysis plant. Biochar is a versatile, carbon-rich and stable material. As a soil additive, it increases the water retention capacity, the pH value and absorbs nutrients that are important for the plants like a sponge, thus preventing them from being washed out of the soil by heavy rainfall. 65% of the Tanzanian population lives from agriculture. By developing and testing a charcoal fertiliser that is perfectly adapted to local conditions, we are contributing to the country’s fertility.

Additionally, atmosfair and the project partner Dark Earth Carbon are planning the construction of a second pyrolysis plant to produce biochar in Tanzania. The new plant is to be built in the Kigoma region in the far west of Tanzania. In this part of Tanzania, there is a lot of subsistence farming (including rice, maize, sunflowers and oil palm), resulting in substantial amount of crop residues and waste from post-harvest agri-processing, which is currently either incinerated or left to rot. Some of this residual biomass, together with organic food waste, will serve as input material for the pyrolysis plant. The plant will process approximately 15,000 tonnes of biomass per year into about 3,750 tonnes of biochar.

Background information biochar

Plants absorb CO2 from the air through solar energy and incorporate carbon into their cell structures. In doing so, they naturally remove CO2 from the atmosphere. Humans can process plant biomass into biochar before decomposition begins, preventing the release of CO2. The carbon remains stored in the earth for centuries in the form of biochar, even when it is simply applied to the topsoil or plowed under. Biochar resists biological decomposition in the soil due to its unique structure. To ensure its effectiveness, the ratio of hydrogen to organic carbon in the composition of biochar must fall below a certain threshold, as outlined in the document (Persistence of biochar in soil). This can be conclusively tested in the laboratory. When this ratio is achieved, science indicates that a maximum of 0.3% of biochar is decomposed annually, as stated in the document (Senkenpotenzial), resulting in minimal CO2 emissions. After 100 years, at least 74% of the carbon is securely bound in the soil. This calculation subtracts all emissions generated during the project when determining the negative emission.

Biochar has many other positive effects. In addition to binding CO2 in the soil, it can also be used as a carrier material for nutrients and thus to enrich the soil. In tropical soils in particular, it can lead to increased crop yields. The biochar absorbs the water from heavy rainfall in the monsoon and releases it back to the plants over a period of weeks. As a water reservoir, it prevents nutrients from being flushed out of the soil. Other important factors also come into play: the basic cycles of the ecosystem are maintained. The biochar is returned to the soil exactly where the plants grew. Important minerals and trace elements are retained and the soil does not leach out. Biochar thus combines carbon storage with sustainable agriculture.

Our Partner

Dark Earth Carbon is a Tanzanian company that is committed to climate protection and improving quality of life. The combination of carbon storage and the improvement of soil fertility, which also has a direct positive impact on the quality of life of the local population, is particularly important to them. The founders of Dark Earth Carbon have many years of experience in working with the rural population and in organic farming in Tanzania.

Your contact at atmosfair

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