According to the Agency for Renewable Resources (FNR), the theoretical biomass residual material potential in Germany currently accounts for around 151 million tonnes of dry matter. The biomass consists of a total of 77 different biomass types such as agricultural waste, municipal waste or wood and forestry residues. Around 31 million of the 151 tonnes are left unused each year and are mostly destined for thermal utilisation (combustion)¹. However, from an environmental point of view, the latter is by far the most unfavourable disposal method. The carbotwin technology developed by the start-up company carbonauten now offers an environmentally friendly alternative for biomass use on the market.

According to Torsten Becker, founder and managing director of carbonauten UG, this innovative technology boasts many other advantages in addition to environmental friendliness: "Due to the modular and robust design with no rotating parts and the energy-positive carbonisation process, our plants are very efficient and flexible for many different biomasses,” Becker explains. The technology was developed and tested in collaboration with an engineering company in the Netherlands. One plant module comprises 4 retorts, i.e. reactors, in each of which up to 5m³ of biomass can be charred into charcoal. Carbonisation, or charring, takes place by way of pyrolysis using a so-called batch process in which biomass does not have to be continuously fed into the reactors, which can then remain closed during the carbonisation process. As the name carbotwin suggests, one module consists of two identical heat chambers, each containing two retorts. A heat chamber is used for carbonisation, which takes place at temperatures of between 220 °C and 650 °C and, depending on the biomass, takes between 3 and 6.5 hours. The retort is then removed from the heat chamber and cooled for about 3 hours before the biochar is removed.

The decisive advantage of the technology is that during carbonisation, synthesis gas is produced, which can be converted into high-temperature heat of 700 kW to 1,000 kW and partly used to heat the heat chambers. Due to the low energy consumption of the production process, the technology has a positive energy balance. "This means that, in addition to high-quality biochar, we can produce electricity and heat," explains Torsten Becker, clearly enthusiastic about the method. In concrete terms, this means that 1,600 tonnes of biochar and 8,000 MWh of heat can be produced per year and module.

The plan is to sell the biochar thus produced to large charcoal manufacturers, which can then sell the charcoal as a particularly environmentally friendly product. "Conventional charcoal comes mainly from dirty sources and contains tropical wood," says Becker. In 2017 alone, around 217,000 tonnes of charcoal worth 18 million euros were imported into Germany - making Germany the largest consumer in this market in the EU. A major concern is that the wood used for producing charcoal often comes from Paraguay or Nigeria where the prices are much lower than elsewhere². As a result, deforestation is occurring at an alarming speed. This development could be counteracted with biochar produced using the carbotwin process.

Due to the low number of personnel required, low operating costs and the cheap price of residual biomass (for example, wood residues from sawmills), the charcoal produced by carbonauten is even cheaper than the charcoal produced from fossil resources by competitors. "A plant with three modules generates around 3 million euros in revenue, resulting in an EBITDA (earnings before interest, taxes, depreciation and amortisation) of around 1 million euros. The figure does not yet take into account the potential sale of the heat or energy produced. No more than two modules are needed to make the technology economically viable,” says the carbonauten managing director. He also emphasises that cooperation with local recyclers, sawmills, waste disposal companies and municipalities is key, enabling the biomass to reach the carbonisation plant without long transport routes.

"Decentralisation is very important to us," says Becker. “This also makes sense from an ecological point of view,” he adds. Other potential customers besides charcoal producers are activated carbon producers and the agricultural sector. Preliminary contracts have already been signed with an activated carbon producer and a charcoal producer, and positive feedback has been received from the agricultural sector. Farmers who use biochar, for example, as an additive for pig or chicken feed, demonstrably need fewer medicines for their animals, which also become livelier and gain weight. Biochar can also be used as a soil additive.

Other fields of application such as biochar foams for the construction sector or biocarbon-based plastics are under development. To keep up to date, the carbonauts cooperate with various research institutions, including the University of Hohenheim, participating directly in the development of innovative, environmentally friendly products for the bioeconomy.

The cascade use of resources and the closing of material cycles are particularly important to Becker. "It's not just about profit," says Becker, "we aspire to contribute to a biobased, environmentally friendly and socially responsible way of doing business. I am convinced that we can do this with the help of carbonauten. "The technology would therefore be suitable for decentralised use in Africa or South America, where a huge amount of biomass accumulates, and which could then be used relatively simply on a regional level. This could also sustainably strengthen the local economy. Promising contacts with South Africa already exist. However, the company founder has already set his sights on the Arabian Peninsula, where there is high demand for charcoal, and Australia, and initial contacts have been made.

In Germany, the first plant will be erected in Eberswalde (Brandenburg) and several will be established in Baden-Württemberg. "We expect to have erected 15 to 20 new plants in different sites and employ a workforce of about 250 employees by 2026. Our goal is quantitative and qualitative market leadership in Europe, with at least 100,000 tonnes of biocarbon. In Baden-Württemberg alone, there is huge untapped potential in the bioeconomy field. For example, our technology also has the potential to contribute to solving the municipal waste disposal problem,” explains Becker. The enthusiasm of the company founder leaves us in no doubt that the carbonauts will succeed. Pioneers like Becker and his colleagues are already a driving force for the expansion of the bioeconomy in Baden-Württemberg, Germany and worldwide.

References

1 FNR (2015): Volume 36: Biomassepotenziale von Rest- und Abfallstoffen - Status Quo in Deutschland. Online at: https://mediathek.fnr.de/band-36-biomassepotenziale-von-rest-und-abfallstoffen.html [10th July 2018]

2 Augsburger Allgemeine (2018): Gefährdete Tropenhölzer: das schmutzige Geschäft mit der Grillkohle. Online: https://www.augsburger-allgemeine.de/wirtschaft/Gefaehrdete-Tropenhoelzer-Das-schmutzige-Geschaeft-mit-der-Grillkohle-id51624076.html [24th July 2018]