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Dissertation by Andreas Arlt on Processing of Biowaste to Biofuels published [27.02.2004]


The dissertation of Andreas Arlt has recently been published as a research report (Report No. 6949) of the Forschungszentrum Karlsruhe GmbH. Andreas Arlt, who holds a degree in Chemical Engineering of the Technical University of Karlsruhe (TH), Germany, prepared his PhD thesis on "Processing of Biowaste to Biofuels - a comparison of process chains for sewage sludge, organic and woody waste using a systems analysis approach". In his thesis, he analyses the extent to which biofuels produced of biowastes can contribute to the nation's renewable energy supply and which amount of CO2 emissions can thus be avoided .

As shown in his work, due to the enormous amount of existing and produced biowastes, these waste types could significantly contribute to an innovative electricity and fuel supply exclusively based on renewable energy sources. Hence, the use of biowaste as biofuels could reduce the nation's CO2 emissions and help Germany to meet its obligation under the Kyoto Protocol to reduce CO2 emissions by 25 % in 2005 compared to 1990's emissions.

However, biowaste can hardly be used for energetic purposes in its original state. It has to be treated using process chains consisting of technical components, such as dewatering, drying, chopping, shredding, etc., and logistics, such as transportation, collection and storage. In the present study, the conversion of organic waste into biofuel was investigated for three different waste types: sewage sludge from municipal sewage treatment plants, separately collected biowaste from households, and woody waste from private gardens, municipal parks and landscape maintenance (hedges and trees, e.g. along country roads, between fields and on nature reserves). The goal of the study was to show which process technologies are available on the market, what costs are involved and how much energy is consumed to produce a storable, microbiologically inert biofuel from organic waste.

The results show that the total costs for processing and disposal are comparable to other disposal alternatives, such as dumping or producing compost, and the energy balance for all process chains investigated is positive. If the available amount of sewage sludge, organic and woody waste is used for energetic purposes alone, about 1.1 % of Germany's electricity demand can be covered and the emission of carbon dioxide can be reduced by 4.0 mio. MG.

Andreas Arlt has finished the examination procedure for his doctorate in passing the oral examination on 17 November 2003 at the University of Stuttgart. The following three professors were members of the examining body for this final examination:

  1. Prof. Dr.-Ing. Helmut Seifert, Head of the Institute for Technical Chemistry, Unit Thermal Waste Treatment and Disposal (ITC-TAB) at Forschungszentrum Karlsruhe
  2. Prof. Dr. Armin Grunwald, Head of ITAS und Professor for Technology Assessment and Systems Analysis at the Department of Applied Sciences, University of Freiburg/Breisgau
  3. Prof. Alfred Voß (Chairman), Head of the Institute of Energy Economics and the Rational Use of Energy, University of Stuttgart.

The Department of Mechanical Engineering of the University of Stuttgart awards him a doctorate in process engineering. From 1999 to 2002, Andreas Arlt worked as a scientist at the Institute for Technology Assessment and Systems Analysis (ITAS) at Forschungszentrum Karlsruhe GmbH. He is the first PhD graduate of the Institute, since Prof. Armin Grunwald has become head of the institute in the year 2000.

The research report can be ordered from:

Hauptabteilung Bibliothek und Medien, Zentralbibliothek, des Forschungszentrums Karlsruhe Address: Postfach 3640, D-76021 Karlsruhe, Germany,
Tel.: +49 (0) 721 / 608 - 25811,
Fax: +49 (0) 721 / 608 - 26521,
E-Mail: baerbel michaelOfv1∂hbm fzk de

Since 1 December 2002, Andreas Arlt has worked for the United Nations Environment Programme at the duty station in Geneva, Switzerland. As a member of the Secretariat of the Basel Convention, he focuses on the environmentally sound management of PCB containing equipment and PCB wastes. In addition, he works on projects focusing on the environmentally sound management and disposal of biowastes and the related potential contribution to the reduction of greenhouse gases.

His details are as follows:

United Nations Environment Programme
Secretariat of the Basel Convention (SBC)
11-15, Chemin des Anémones
CH-1219 Châtelaine
Genève, Switzerland
Tel.: +41 22 917 8364
Fax: +41 22 797 3454
E-Mail: Andreas.Arlt∂unep.ch

Arlt, Andreas:
Systemanalytischer Vergleich zur Herstellung von Ersatzbrennstoffen aus biogenen Abfällen am Beispiel von kommunalem Klärschlamm, Bioabfall und Grünabfall. Karlsruhe: Forschungszentrum Karlsruhe 2003 (Wissenschaftliche Berichte, FZKA-6949 sowie Dissertation, Universität Stuttgart 2003)
Full text in German only/pdf (1 973 kb) German abstract/htm English abstract/htm Table of contents/htm