Biological production of gaseous biofuels
from biomass

Hydrogen is considered to be the energy carrier of the future. The present routes for producing hydrogen gas are all based on highly energy-demanding processes and the raw material often originates from fossil resources. However, to become an important energy carrier, hydrogen needs to be produced with energy efficient processes from renewable raw materials.

The above mentioned criteria are fulfilled by a process currently under development which is a biological conversion process. The main process consists of four steps; pretreatment of biomass, two fermentation steps (thermophilic and photoheterotrophic fermentation) and gas upgrading. In the pretreatment, the sugars in the raw material (sugar beet, wheat, potato, miscanthus) are made available for the thermophilic bacteria. Different pretreatment techniques are used depending on raw material. These can be hot water extraction, extrusion, starch liquefaction, enzymatic hydrolysis etc and combinations of these. In the thermophilic fermentation the bacteria convert mono- and disaccharides to hydrogen, acetic acid and carbon dioxide at about 75C. In the following photoheterotrophic fermentation the acetic acid is converted to hydrogen and carbon dioxide. As the name implies the photoheterotrophic bacteria need light in order to produce hydrogen. Finally, to obtain a product useful as a fuel or for heat and power production, the hydrogen gas needs to be separated from carbon dioxide, water, acetic acid, and other volatile compounds and this is done in the gas upgrading step. For this purpose, methods such as membrane separation, amin-adsorption, pressure swing adsorption, drying or compression can be utilized.

The aim of the project is to develop models for single units operations as well as for the overall process design and to perform process simulations. The work is performed using mathematical tools such as MATLAB (The Mathworks, Inc) and flowsheeting and process evaluation programs such as Aspen Plus and Aspen Icarus Process Evaluator (Aspen Technology).

Publications

Articles

Techno-economic evaluation of a two-step biological process for hydrogen production, Biotechnology progress (2010), 26(2), 496-504

Conferences

Technical Evaluation of a Biological Hydrogen Production Process - Visual presentation at 15th European Biomass Conference and Exhibition - Berlin 2007

Techno-Economic Evaluation of Stripping Alternatives in Thermophilic Fermentation for Hydrogen Production - Visual presentation at the 18th International Congress of Chemical and Process Engineering - Prague 2008

Biological hydrogen production from biomass - Strategies to reduce energy demand and production cost - Oral presentation at the International Conference and Trade Fair on Hydrogen and Fuel Cell Technologies - Hamburg 2008

Biological hydrogen and biogas production - Techno-Economic evaluation of an integrated process - Visual presentation at the 31st Symposium on Biotechnology for Fuels and Chemicals - San Francisco 2009

Techno-economic Evaluation of an Integrated Biological Hydrogen and Methane Production Process - Oral (key note) presentation at the 17th European Biomass Conference and Exhibition - Hamburg 2009

Integrated biological Hydrogen and Methane Production - A Techno-economic Study of the Impact of Fermentation Strategies on Production Cost - visual presentation at the 18th European Biomass Conference and Exhibition - Lyon 2010

Members

Guido Zacchi, Professor
Mattias Ljunggren, PhD student

Partners

The project is part of the EU funded project Hyvolution, which deals with the above explained process. The project consists of 6 research oriented work packages dealing with everything from gene expression in thermophilic and photoheterotrophic bacteria, bioreactor design, microbial kinetic modelling to biomass availability, economic process evaluations and societal acceptance. The work packages are summarized in the graphics below.