Synthesis gas for fuel – directly from forest residues

Published: 2 April 2012

Forest residues such as stumps, bark and twigs are now proving of great benefit in a new test facility for the production of high-quality synthesis gas intended for transport fuels. The results which are unique in Scandinavia, are based on close cooperation between Luleå University of Technology, the Energy Technology Centre (ETC) and industry. By applying known gasification technology, valuable synthesis gas has been obtained from waste materials from the forest.

"We chose to take the shortest route and make use of, for example, tree stumps and the tops of trees from the forest and use them as they are in our facility.Primarily, we use make use of low-quality forest residues which the wood and paper industry cannot use.People often talk of the need to pre-treat these kinds of raw materials or to use it with charcoal to produce synthesis gas effectively.What we have done is to show how to use forest residues directly – and this is an important aspect of our success," says CEO Magnus Marklund, at ETC in Piteå.

The 8 metre high IVAB-manufactured gasifier stands in the robust gasification laboratory at the ETC in Piteå. It has succeeded with that which many scientists have tried to achieve for several years; to produce high-quality synthesis gas from forest residues.The gasification project at ETC is based on simplicity, with the direct input of untreated pulverised forest residues, but with intricate technical challenges, which scientists and engineers at ETC, LTU, IVAB (commercial partner) have worked with for three years via a project financed by the Swedish Energy Agency, IVAB, Sveaskog and Smurfit kappa.

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"The actual input of the raw materials in the gasifying apparatus is a challenge.It is a pressurized process and the powder that is fed into the gasifier is composed of fibres and particles, which vary in characteristics depending on the origin of the material, for example whether it comes from birch or pine forests.It places great demands on the design in order to achieve a smooth and stable feed into the gasifier," says Fredrik Weiland, research engineer at ETC and also a PhD student at Energy Engineering at Luleå University of Technology.

To minimize unwanted nitrogen when the synthesis gas is produced, pure oxygen and carbon dioxide is used when the raw material is transformed into synthesis gas in the gasifier.

 "Our synthesis gas has very low levels of hydrocarbons which is good when you want to produce fuels from gas.A possible final product could be methanol, hydrogen and even synthetic benzine," says Magnus Marklund.

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There are long-drawn out plans for a further three years of research funds for continued work with the technology. The project will therefore most likely continue to involve many PhD students from LTU.  Some of the students who are working in the project today comment below on their assignments:

Burak Göktepe, PhD student in Energy Engineering, LTU: "This research project is linked directly to the real world, it makes the work so enjoyable and interesting for me as a PhD student. My focus is primarily on the use of different measurement methods and the stability of the process."

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Jim Anderson, PhD student Energy Engineering, LTU: "I am investigating how our industrial process can be developed and I am trying to create a model that can be used commercially. My challenge is to validate a future large-scale process that does not yet exist, but which will be 100 times greater than the one we are now testing, plus it will be commercially viable."

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Charlie Ma, PhD student, Energy Engineering, LTU: "I am studying how to avoid problems with the ash that is produced during the gasification process. Ash can react for example with the materials in the reactor and limit its life, depending on what materials and fuels we use. The difficulty is that the process does not take place in a controlled environment, and that impact of the ash on the material requires quite extensive experiments which take a long time."

An interesting commercial solution for the future which has potential, can be a combination of the production of synthesis gas from forest residues with black liquor gasification in connection with the paper pulp industry.