Terra Preta from Green Cut
In Germany, around 4.5 million tons of green waste and 3 million tons of landscaping waste are produced annually on the area of 357,582 km². All together, that's 7.5 million tons of woody and herbaceous waste material*). In relation to 270 relevant administrative districts²*), this means that in each of those districts, an average of 28,000 tons of waste material from green waste and landscape management is generated annually. Of the 28,000 tons of material, around 10,000 tons are wood and 18,000 tons are herbaceous.
The 10,000 tons of wood material can be carbonized in industrial pyrolysis plants to approx. 3,000 tons of biochar. 1,800 tons of this biochar can be used with the herbaceous material and “charged” with excretions from the farm animals. This mixture is processed into approx. 18,000 tons of Terra Preta after a fermentation process.
The remaining 1,200 tons of the biochar can be marketed at market prices, e.g. as feed charcoal, filter charcoal, medicinal charcoal or simply as barbecue charcoal. The potential of these processes for carbon bonding, humus build-up and greenhouse gas (CO²) sequestration are aptly described by the German Federal Environment Agency *).
An industrial plant for the carbonization of 10,000 tons of wood or 30,000 tons of green waste material has a turnkey investment volume of approx. € 10 million.
If this carbonation plant is built under municipal control with state subsidies, you can achieve the maximum effect on the way to climate neutrality: The operation of the company is organized by a cooperative, which is supported by the farmers of the district. This allows to reduce drastically the prices for Terra Preta or biochar, which are currently too high for broad use. Since the product prices reflect the operating costs only, this scenario generates a ton of Terra Preta for less than € 100, at least for the members of this cooperative.
This enables a large-scale application of biochar substrate and humus formation on the land of all farmers involved - and opens the way to climate-neutral or climate-positive agriculture at the district level.
Dr. Stephan Martini, Okt.2021
*) Source: Federal Environment Agency, costs and benefits of optimized bio-waste recycling with regard to energy efficiency, climate and resource protection, texts 43/2010 (e.g. p. 36, Fig. 8 and p. 66, Tab. 10)
²*) City-states and predominantly industrially oriented rural districts were excluded from consideration.
³*) ROI = Return on Invest
