BioCharOpt

Driven by the recent significant increase in public awareness of climate change and its impact on our lives as well as the objectives of the EU Green Deal, measures to reduce greenhouse gas emissions are increasingly being developed and implemented. While the transformation to a CO₂-free future is already in full swing in the heating and transportation sectors, e.g. through the increased implementation of renewable energy source-based heating systems and e-mobility, the industrial sector demands for appropriate technical solutions. Especially energy intensive industries in many sectors still lack for economically sound decarbonisation technologies.

For the latter carbon capture (CC) from flue gases combined with storage (CCS) or utilisation (CCU) of CO₂ would be options, however, related solutions are only economically feasible for large-scale applications and most technologies available are still in the development resp. demonstration stage. The best and most interesting option is the substitution of fossil by renewable fuels, in case of the project proposed the utilisation of biochar and renewable gas (pyrolysis gas) instead of fossil coal and natural gas in industrial processes, especially in the metallurgical industry. Biochar is typically produced from biomass in slow pyrolysis processes. Mature technologies therefore already exist, however, drawbacks regarding their pyrolysis gas quality as well as energy efficiency are given which make them not attractive for industrial applications.

Against this background, BioCharOpt aims at the development of a novel system based on a continuously working counter-current biomass pyrolysis (CCP) process directly coupled with a pyrolysis gas (PG) treatment based on plasma technology combined with a novel high-temperature tar reforming catalyst (HT-TRC). Following this approach, the PG, which contains about 50% of the heating value supplied with the feedstock, shall become suitable for direct application in gas engines, gas turbines or industrial gas burners. An advantage of CCP thereby is that it provides a virtually dust-free PG which enables new approaches for tar reforming. With this technology high-quality biochar, heat and electricity resp. renewable gas shall be produced at very low harmful emissions and a conversion efficiency of the feedstock (NCV) into marketable products of more than 90%, making the new concept economically attractive. Abundantly available low-grade biomass waste materials shall be utilised as feedstock which assures a sustainable approach. The new technology shall be developed for a biochar production capacity of up to 2,000 t/a, which opens a huge potential for applications in energy intensive industries. However, the high-quality biochar produced shall also be suitable for other applications (e.g. as soil amendment or as additive in animal feed production) where it results in considerable GHG sequestration (carbon credits). Thus, a broad applicability is given.

BioCharOpt shall strongly contribute to achieve the objectives of the call since the issues listed below are central elements of the project:

• Increasing process and resource efficiency
• Alternative fuels & raw materials, bio-based resources, integration of renewable energies
• Alternative materials & energy-efficient processes

Project Progress

The principal feasibility of this approach has already been proven in a previous project, but also relevant weaknesses and demands for further R&D have been identified, on which the project proposed focuses. In order to control and optimise the biochar quality, false air inputs into the reactor shall be minimised and a fully automatic bed height control shall be developed. Furthermore, a concept for the targeted injection of water vapour into the reactor shall be developed in order to increase heat transfer and thereby enhance the material throughput and improve biochar quality.

In order to be able to use the pyrolysis gas in gas engines or industrial gas burners, the tars it contains have to be reformed. To this end, the project aims at the development of a new concept based on combined thermal and catalytic tar reforming. For the first time in biomass pyrolysis, a thermal plasma shall be used to heat the gas conversion zone. This direct heating results in very good heat transfer and also introduces O-, H- and OH-radicals, which accelerate tar reforming. Compared to indirect heating, the complexity of the system is also significantly reduced. For the subsequent catalytic tar conversion, with which a tar content of less than 100 mg/Nm³ shall be achieved (corresponding to an overall tar reduction of 99%), a new high-temperature catalyst optimised for this application shall be developed.

The project is based on CFD and process simulations for the development of the new components, on laboratory reactor tests for catalyst development and on the development, design and construction of a testing plant for experimental validation and step-wise improvement of the plant technology. Accompanying economic evaluations and risk analyses are intended to support an economically attractive solution. At the end of the project, an experimentally validated technology and system designs for industrial plants (1000 and 2000 t/a biochar production) should be available, which should form the basis for a subsequent demonstration project.

(Expected) Results

Development and successful validation of a continuously operating fully automated counter-current biomass pyrolysis process directly coupled with a pyrolysis gas treatment based on plasma technology combined with a novel high-temperature tar reforming catalyst at the end of the project. The C-content of the biochar shall be 85% (dry basis), the target tar content of the pyrolysis gas shall be below 100 mg/Nm³ with almost zero dust content and the overall efficiency of the process shall be >90%. TRL 5 is expected at the end of the project.