August 13th, 2020
The Karlsruhe Biomass-to-Liquid process is particularly suited to the requirements of the widely distributed biomass production from agriculture: The rapid pyrolysis and production of the bioslurry are carried out at a large number of decentrally located plants. They provide the decisive enhancement in energy density needed for further economical transport of the raw materials. The gasification and the following steps of gas conditioning and synthesis can then be performed at a large central installation of a size which makes it commercially cost-effective, and which is supplied with the bioslurry raw material by road or rail transport.
In this way, using the bioliq process, a ton of synthetic fuel can be produced from about seven tons of air-dried straw. Up to 40 % of the energy originally present in the biomass remains in the liquid product. Byproducts are heat and electric power which can be used to fill the energy requirements of the entire process.
In a possible scenario, about 40 rapid-pyrolysis installations, each with a capacity of 200,000 tons of bioslurry annually, could be set up to supply a central gasification and fuel production plant with an annual capacity of a million tons of fuel. Then, at a price of 70 N per ton for the air-dried starting material, a production price of less than one N per kg of fuel could be realized . With integration of the gasifier into an equipment network of, for example, the chemical industry, the diversification of the usable products can also be broadened. Along with the methanol route, preferred in the Karlsruhe process, and in addition to DME which is under discussion as an alternative liquefied-gas fuel, many oxygen-containing basic chemical products, the so-called oxygenates, can be produced. Ethylene and propylene, the starting materials for roughly half of the world’s plastics production, can also be synthesized in this way. Besides the option of the utilization of biomass as a source of carbon, necessary in the long term, economically favorable processes could also be developed in the foreseeable future.
The focus for the process development is currently on low-grade biomass, which thus far has not been used at all, such as surplus grain straw, barn straw or waste wood. The use of solid wood is not seen as a fruitful solution in the long term. Even though this less problematic starting material might permit the technical realization of the process to be achieved more rapidly, it can be expected that the demand for solid wood will increase due to its uses in construction, for cellulose manufacture, and for decentralized and household heat and energy production.
The accompanying systems analysis research [1,14] leads us to expect an annual production of about 5 million tons of synthetic motor fuel from the use of waste forest wood and surplus straw alone, together about 30 million tons of dry starting material. This corresponds to roughly 10 % of the current consumption of petrol and diesel fuels in Germany . Combined with other biochemical and physico-chemical processes, a still higher-quality utilization of the biomass, in the form of a biomass refinery, should be feasible. Similarly to today’s petroleum refineries, it would use a broad spectrum of raw materials to produce a variety of basic chemical products and fine chemicals, making use of synergy effects to increase economic productivity, which would result in a clear-cut reduction of the consumption of fossil resources by the chemical industry.
For support of the bioliq® pilot plant, we thank the German Federal Ministry for Nutrition, Agriculture and Consumer Protection (BMELV), the Agency for Sustainable Raw Materials (FNR), the State of Baden-Wurttemberg, and the European Union.
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Synthetic fuels from the biomass can provide an important contribution to a renewable energy economy. The Karlsruhe BtL concept bioliq® aims at bringing decentral production in line with centralized processing on an industrial scale. To this end, thermochemical methods are employed: rapid pyrolysis for the production of a readily transportable, energy-rich intermediate product, and entrained-flow gasification to yield synthesis gas and to process it further into the desired fuels. The bioliq process was distinguished with the BlueSkyAward by the UN Organization UNIDO in 2006.
About the Authors
Nicolaus Dahmen studied chemistry at the Ruhr University in Bochum, obtained his doctoral degree in 1992 and moved in the same year to the Karlsruhe Research Center, now KIT. There, he is currently concerned with the thermochemical transformation of biomass into gaseous, liquid and solid fuels. As project leader, he is responsible for the construction of the bioliq® pilot plant. In 2010, he obtained his Habilitation at the University of Heidelberg.
Eckhard Dinjus began his studies of chemistry in 1963 at the Friedrich Schiller University in Jena and completed his doctorate there in 1973. In 1989, he obtained the Habilitation, and thereafter he was leader of the Research group “ CO2 Chemistry” of the Max Planck Society. Since 1996, he has been director of the Institut for Technical Chemistry, now IKFT at KIT, and he occupies the chair of the same name at the University of Heidelberg.
Edmund Henrich studied chemistry at the Universities of Mainz and Heidelberg. He received his doctorate in Heidelberg in 1971 and the Habilitation in 1993 in the field of radiochemistry. He has worked at the Karlsruhe Research Center since 1974, and as Division Leader of the Institute for Technical Chemistry there, he is responsible for R and D activities relating to the Karlsruhe BtL process. Since 2005, he has been extraordinary professor at the University of Heidelberg, and is professor emeritus there since 2009.
Dr. Nicolaus Dahmen, Dr. Eckhardt Dinjus,
Dr. Edmund Henrich, Karlsruhe Institute for Technology (KIT), Institut fuer Katalyseforschung und -technologie (IKFT), Postfach 3640,
76021 Karlsruhe, Germany. nicolaus. dahmen@kit. edu