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Volkswagen and Daimler Buy Stakes in BTL Company CHOREN

Volkswagen Aktiengesellschaft and Daimler AG have each acquired a minority shareholding in CHOREN Industries GmbH, Freiberg, a provider of gasification technology. The main goal of the commitment by the two automakers is to promote the widespread market introduction of BTL (biomass-to-liquid) second-generation synthetic fuel.

Volkswagen and Daimler have been investigating potential applications, the economic feasibility and the energy balance of BTL jointly with CHOREN since 2002. The shareholdings in CHOREN acquired by the two companies are an important step towards the systematic use of second-generation biofuels and support the further project development of commercial-scale BTL production plants with a planned annual production capacity of some 200,000 tonnes (approximately 61 million gallons US). (Earlier post.)

CHOREN is currently building the world’s first commercial industrial scale BTL plant (Beta plant) at its Freiberg site. From 2008, the plant is expected to produce approximately 15,000 tonnes (4.6 million gallons) of fuel a year. This would be sufficient to meet the annual requirements of some 15,000 cars.

CHOREN also plans to build the first reference plant in Germany, a Sigma 1 plant, with an annual capacity of 200,000 metric tons. The company intends to  announce a decision on the location of such a plant by the end of the year.

The planned Sigma plants have the potential to contribute significantly towards realizing the German government’s climate protection targets. 10 to 15 CHOREN BTL plants could save up to 3 million metric tons of CO2 by 2020.

Biomass to SunDiesel BTL fuel with Carbo-V gasification. Click to enlarge.

The heart of CHOREN’s technology is its patented Carbo-V Biomass-gasification process that converts biomass into ultra-clean tar-free synthetic gas.

The Carbo-V Process is a three-stage gasification process using:

  • Low-temperature gasification. Biomass (with a water content of 15%–20%) is continually carbonized through partial oxidation (low-temperature pyrolysis) with air or oxygen at temperatures between 400º C and 500° C, i.e. it is broken down into a gas containing tar (volatile parts) and solid carbon (char).

  • High-temperature gasification. The gas containing tar is post-oxidized using air and/or oxygen in a combustion chamber operating above the melting point of the fuel’s ash to turn it into a hot gasification medium.

  • Endothermic entrained bed gasification. The char is ground down into pulverized fuel and is blown into the hot gasification medium. The pulverized fuel and the gasification medium react endothermically in the gasification reactor and are converted into a raw synthesis gas. Once this has been treated in the appropriate manner, it can be used as a combustible gas for generating electricity, steam and heat or as a syngas.

The syngas can then be converted into synthetic biofuels using the same Shell Middle Distillate Synthesis (SMDS) technology that Shell has developed for Gas-to-Liquids production (conversion of natural gas into synthetic oil products). Shell’s SMDS is a low-temperature, cobalt catalyst-based version of the Fischer-Tropsch GTL process. Shell Deutschland Oil GmbH took a minority stake in CHOREN in 2005. (Earlier post.)

Volkswagen has been calling for and supporting the development and industrial production of second-generation biofuels, known as SunFuels, for a long time. Compared with the first generation, these second-generation biofuels can in fact as much as triple hectare yields, they do not compete with food production and they help to reduce greenhouse gases by approximately 90%. With this financial commitment, the Volkswagen Group is supporting the industrial-scale realization of biogenic synthetic fuels as part of its “Driving ideas” campaign, and thus systematically continuing to move closer to sustainable mobility.

—Dr. Wolfgang Steiger, Volkswagen Head of Group Research, Powertrains

The partners will also be stepping up cooperation to shape the framework for the sustainable market introduction of BTL fuels.


Rafael Seidl

In case you're wondering why these automakers are investing in a BTL producer, the answer is simple: the compromise reached with the EU is that fleet average CO2 emissions will be limited to 130gCO2/km at the tailpipe based on the NEDC, provided automakers also deliver the "equivalent" of 10gCO2/km in ancillary measures such as biofuels, tire pressure monitoring systems, gear change assistants etc. Just how the fleet averages and this equivalence will be computed is currently a matter of negotiations behind closed doors.

BTL is perhaps the most promising near-term approach to creating high-quality transportation fuel from general biomass (provided it's dry enough). F-T may be a sledgehammer compared to enzymatic processes but it can be applied at industrial scales today - cellulosic ethanol technology isn't as far along yet and more sensitive to feedstock quality. Since Europe has always set its emissions regs at levels that permit diesel vehicles to be built at reasonable prices, it can pursue bio-alternatives to both petrol and diesel at the same time.

Note that F-T yields increase substantially if additional hydrogen is provided. Obviously, that raises the twin questions of where you get it from and if there are any better uses for it.


I recall that when Purdue researchers suggested adding hydrogen to FT
they were blasted from all sides. I think the term H2CAR was used one time. I wonder if various poor H2 sources might somehow get amplified in a combined process eg sunlight on wet titanium dioxide, electrolysis, nuclear hydrogen, reformed methanol.

Rafael Seidl

I re-read my comment on the post you refer to and see no contradiction. BTL - unlike CTL - is a green fuel. BTL production can be enhanced by adding hydrogen you have to get it from somewhere.

The cheapest options for high volumes are steam reforming natural gas and, electrolysis of water using electricity produced in nuclear power plants. However, neither method is cheap compared to dino-fuel and nuclear in particular is not exactly green. Renewable hydrogen via solar, wind, hydro etc. would be clean but is very expensive indeed.


I remember someone on here saying that biomass was too moist to gasify. So much for that statement.



15-20% humidity is content of partially dried wood. Currently wood and other dry biomass waste are co-combusted in coal boilers, used for heating, and production of wood pellets and alike. BTL technology allows to convert this resource to much more valuable liquid fuel.

Wet biomass, like most of agricultural waste, food processing waste, corn stove, grass clipping, etc. is not feasible to gasification. Too high water content, and in most cases it is very tricky to dry, like in organic sludge. Small and medium scale wet fermentation is the way to go for wet biomass.


I have read one German prof state that the Choren process could meet all of Germany's fossil fuel demands, including air transport, while being realistic as to the amount of land used.

Paul Dietz

A problem with gasifying biomass is the chemical composition of the ash. As I understand it, the higher level of alkali makes it more corrosive than the slag you get from, say, coal.

fred schumacher

Perennial grass biomass plants would be harvested after full senescence, after translocation of nutrients into the underground root system. The plant dries on the stalk and would be at less than 15% moisture content at harvest. Grass that is cut wet, for hay, is allowed to dry on the ground to under 15% moisture before it is baled. Green wood is usually 30% moisture and would need to be air-dried, the same as is done now for firewood. In all these cases the drying is done by sun and wind, without artificial heat application -- ordinary agricultural processes that have been done for thousands of years.


Ash is a big problem and moisture is too. But I would not want to dismiss gasification of biomass just because it is old and there is moisture.

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