Energy Engineering

We focus principally on developing technologies for converting inedible biomass such as waste wood, farmyard manure, slurry and maize straw into high-quality chemicals and fuels.

Dwindling fossil fuel resources and the need to reduce greenhouse gas emissions necessitate the use of lignocellulosic biomass to produce chemicals and liquid fuels for powering the air transport and heavy-lift cargo industries as well as methane for seasonal energy storage.


The Laboratory for Bioenergy and Biochemicals specialises in biotechnological conversion of lignocellulosic biomass such as waste products from agriculture and forestry. We offer the following services:

  • Quantitative analysis of the composition of plant biomass (hemicellulose, cellulose, lignins, proteins and fats)
  • Optimising steam pretreatment of various biomass feedstocks
  • Processes for high-pressure extraction of biomass
  • Enzymatic hydrolysis and fermentation of lignocellulosic biomass
  • Strictly anaerobic fermentation technique
  • Breaking down and determining the bio-methane potential of the individual substances in biomass during anaerobic fermentation


The scope of research pursued by the Laboratory for Bioenergy and Biochemicals is aimed at developing biotechnological processes for converting lignocellulosic biomass into high-quality chemicals and fuels. Our two main focuses in this field are, firstly, biomass pretreatment technologies and, secondly, consolidated bioprocessing based on a consortium of micro-organisms for direct conversion of lignocellulosic biomass into chemicals.

Pretreatment of biomass

Efficient biochemical conversion of lignocellulose into chemicals requires that the biomass feedstock be pretreated to break down the bonding of the polymer structures in the biomass. Pretreatment is needed to enable enzymes to access the cellulose. We focus on the steam explosion process as a pretreatment method, a technology being applied today in the first industrial-scale cellulose-to-ethanol plants. We investigate such challenges as how best to optimise pretreatment, fraction biomass into its individual constituent components, and continuously feed abrasive biomass to the high-pressure reactor.

Consolidated bioprocessing

The term ‘consolidated bioprocessing’ is generally understood today to mean the use of genetically modified ‘super bugs’ capable of producing cellulolytic enzymes while at the same time fermenting the sugars released to create a target product. We’ve developed in our laboratory a method of consolidated bioprocessing based on a microbial consortium. A special reactor was designed for this purpose that successfully creates local ecological niches allowing micro-organisms with differing abiotic requirements (concerning e.g. oxygen) to live together symbiotically. 


Lignocellulosic biomass is an attractive resource for producing sustainable fuels and valuable chemicals. Using residues from agriculture and forestry for this purpose, such as maize straw and wood waste, is a particularly attractive option, as such matter offers no competing usage for producing foodstuffs or feed. Another important factor driving its acceptance among the general public is that these renewable fuels and chemicals can directly replace fossil fuels without requiring, for example, any new types of engines. The objective of this project is to produce sustainable fuels and chemicals (alkanes and alpha-olefins) from residues of agricultural and forestry undertakings by combining a sequential series of biochemical and catalytic conversion steps. The three associated sub-projects are dedicated to investigating the two most important conversion processes and assessing process and product sustainability along the entire value chain.

Sustainability evaluation Enlarge image

Farmyard manure (i.e. solid manure and slurry from livestock) is hardly ever used in Switzerland to produce biogas due to its poor fermentability. The aim of these efforts is to significantly increase the biogas yield of this feedstock by improving the fermentation process. To this end, we’re developing a process that uses microbial means to access those constituent components of farmyard manure whose biogas potential until now could not be utilised. The project is being financed by the Swiss Federal Office of Energy.

Mikrobielle Strategie zur Erhöhung der Biogasausbeute von Hofdünger Enlarge image

In this project we’re investigating and optimising the process of steam explosion of cattle slurry (liquid manure) as a potential method for pretreating this biomass feedstock to increase the biogas yield of the downstream anaerobic fermentation. The project’s objective is gain detailed understanding of the effects of pretreatment on the individual components of the slurry feedstock and on the achievable biogas yield. Furthermore, an innovative reactor is being developed for this pretreatment process that enables recovery and re-use of heat-temperature thermal energy. The project receives support from the Swiss Competence Center for Energy Research and ERA-NET Bioenergy.

Dampfvorbehandlung von Rindergülle zur Verbesserung der anaeroben Verdaubarkeit Enlarge image

Consolidated bioprocessing, in which a microbial consortium directly converts solid biomass into a chemical such as ethanol, has been successfully established on a laboratory scale (in 3-litre batches). The next step is to upscale the process to a small pilot scope of 200 litres. We're currently generating and validating a mathematical model for target-designing the process to a larger scale. The project is being financed by the Swiss Competence Center for Energy Research.


  • Shahab, R.L., S. Brethauer, M. P. Davey, A. G. Smith, S. Vignolini, J. S. Luterbacher and M. H. Studer (2020). ‘A heterogeneous microbial consortium producing short-chain fatty acids from lignocellulose.’ Science 369, eabb1214

  • Shahab, R.L., S. Brethauer, J. S. Luterbacher and M. H. Studer (2020). ‘Engineering of ecological niches to create stable artificial consortia for complex biotransformations.’ Current Opinion in Biotechnology 62, 129-136

  • Brethauer, S., A. Antczak, A., R. Balan, T. Zielenkiewicz and M. H. Studer (2020). ‘Steam explosion pretreatment of beechwood. Part 2: Quantification of cellulase inhibitors and their effect on Avicel hydrolysis.’ 13(14), 3638

  • Balan, R., A. Antczak, S. Brethauer, T. Zielenkiewicz and M. H. Studer (2020). ‘Steam explosion pretreatment of beechwood. Part 1: Comparison of the enzymatic hydrolysis of washed solids and whole pretreatment slurry at different solid loadings.’ 13(14), 3653

  • Brethauer, S., R. L. Shahab, and M. H. Studer (2020). ‘Impacts of biofilms on the conversion of cellulose.’ Applied Microbiology and Biotechnology 104, 5201–5212

  • Xiros, C., R. Shahab and M. Studer (2019). 'A cellulolytic fungal biofilm enhances the consolidated bioconversion of cellulose to short chain fatty acids by the rumen microbiome.' Applied Microbiology and Biotechnology 103(8), 3355-3365
  • Seidel, C.-M., S. Brethauer, L. Gyenge, P. Rudolf von Rohr and M. Studer (2019). 'Two-stage steam explosion pretreatment of softwood with 2-naphthol as carbocation scavenger.' Biotechnology for Biofuels 12:37
  • Rozmysłowicz, B., J.-H. Yeap, A. M. I. Elkhaiary, M. T. Amiri, R. L. Shahab, Y. M. Questell-Santiago, C. Xiros, B. P. Le Monnier, M. H. Studer and  J. S. Luterbacher (2019). ‘Catalytic valorization of the acetate fraction of biomass to aromatics and its integration into the carboxylate platform.’ Green Chemistry 21(10), 2801-2809
  • Yeap, J.H., F. Heroguel, R.L. Shahab, B. Rozmyslowicz, M.H. Studer and J. S. Luterbacher (2018). 'Selectivity control during the single-step conversion of aliphatic carboxylic acids to linear olefins.' ACS Catalysis 8(11): 1076910773
  • Shahab, R., S. Brethauer, J. Luterbacher and M. Studer (2018). ‘Consolidated bioprocessing of lignocellulosic biomass to lactic acid by a synthetic fungal-bacterial consortium’ (2018) Biotechnology and Bioengineering 115(5): 1207-1215
  • Li,M., S. Cao, X. Meng, M. Studer, CE. Wyman, AJ. Ragauskas and Y. Pu (2017) 'The effect of liquid hot water pretreatment on the chemicalstructural alteration and the reduced recalcitrance in poplar.' Biotechnology for Biofuels 10 (237)
  • Xiros, C. and M. Studer (2017) 'Enhancement of cellulolytic effciency of fungal biofilms for consolidated bioprocessing of plant biomass.' Frontiers in Microbiology 8: 1077
  • Pielhop, T., C. Reinhard, C. Hecht, L. Del Bene, M. Studer and P. Rudolf von Rohr (2017). 'Application potential of a carbocation scavenger in autohydrolysis and dilute acid pretreatment to overcome high softwood recalcitrance.' Biomass and Bioenergy 105: 164-173
  • Seidel, CM., T. Pielhop, M. Studer and P. Rudolf von Rohr (2017). 'The influence of the explosive decompression in steam-explosion pretreatment on the enzymatic digestibility of different biomasses.' Faraday Discussions 202: 269-280
  • Brethauer, S., R. Shahab and M. Studer (2017). 'Simultaneous saccharification and fermentation of steam pretreated beech wood with in situ Irpex lacteus treatment.' Bioresource Technology 237: 135-138
  • Pielhop, T., J. Amgarten, M. Studer and P. Rudolf von Rohr (2017). 'Pilotscale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance.' Biotechnology for Biofuels 10 (130)
  • Pielhop, T., J. Amgarten, P. Rudolf von Rohr and M. Studer (2016). 'Steam explosion pretreatment of softwood: The effect of the explosive decompression on enzymatic digestibility.' Biotechnology for Biofuels 9(152)
  • Brethauer, S., and M. Studer (2015). 'Biochemical conversion processes of lignocellulosic biomass to fuels and chemicals - A Review.' CHIMIA 69(10):572-581
  • Thomas, P., G.O. Larrazabal, M. Studer, S. Brethauer, C.M. Seidel and P. Rudolf von Rohr (2015). 'Lignin repolymerisation in spruce autohydrolysis pretreatment increases cellulase deactivation.' Green Chemistry 17(6): 3521-3532
  • Brethauer, S., M. Studer, and C.E. Wyman (2014). 'Application of a slurry feeder to 1 and 3 stage continuous simultaneous saccharification and fermentation of dilute acid pretreated corn stover.' Bioresource Technology 170: 470-476
  • Brethauer, S., M. Studer (2014). 'Consolidated bioprocessing of lignocellulose by a microbial consortium.' Energy & Environmental Science 7(4): 1446-1453


The Laboratory for Bioenergy and Biochemicals is well equipped, furnished not only with standard biotech laboratory equipment, but also the following specialised tools and devices: 

  • Agilent 7890 gas chromatograph equipped with flame ionisation detector (FID) and thermal conductivity detector (TCD) and a GERSTEL multi-purpose sampler (MPS)
  • Waters Alliance 2695 high-performance liquid chromatograph (HPLC) with refractive index (RI) detector and photo-diode array (PDA) detector
  • Dionex ion chromatograph (IC) with pulsed amperometric detector
  • 8 Labfors 5 BioEtOH bioreactors (fermenters) from INFORS HT (3.0-litre vessel)
  • 4 Multifors bioreactors (fermenters) from INFORS HT (0.5-litre vessel)
  • 6 biogas reactors (1.5-litre) with pH, reduction-oxidation (redox), methane and volumetric-flow sensors
  • 19- and 150-litre bioengineering fermenters
  • Labconco laminar flow cabinet
  • LABstar anaerobic glove-box workstation 
  • 3 incubator shakers from INFORS HT
  • Fedegari autoclave
  • 2 Eppendorf centrifuges
  • Hach DR5000 UV/Vis spectrophotometer
  • LECO 628 Series CHN analyser
  • Steam gun (from IAP in Graz, Austria)


Are you interested in working with us or would you like to know more about our research activities in the field of consolidated bioprocessing? We look forward to receiving your e-mail!