PhD defence: Nirmal Ghimire

Nirmal Ghimire at campus Porsgrunn holds a trial lecture and disputation on May 25.

25 May

Practical information

  • Date: 25. May 2021
  • Time: 09.30 - 15.30
  • Location: Porsgrunn
  • Download calendar file
  • Follow on Zoom (click on the link that becomes active when the program starts).


    09.30: Nirmal Ghimire holds his trial lecture «Strategies and challenges in bioenergy process development when utilizing syngas in AD-reactors».

    12.00: Nirmal Ghimire is defending his thesis «Methane Production from Lignocellulosic Residues» for the degree of philosophiae doctor (PhD).

    Evaluation committee

    • First opponent: Associate professor Ilona Sávári Horváth, University of Borås.
    • Second opponent: Dr. Espen Govasmark, VEAS.
    • Administrator: Associate professor Roshan Sharma, USN.


    • Principal supervisor: Associate professor Wenche Hennie Bergland, USN.
    • Co-supervisor: Professor Rune Bakke, USN (deceased).


Portrait of Nirmal GhimireNirmal Ghimire, candidate in the PhD program Process, Energy and Automation Engineering at University of South-Eastern Norway (USN), Faculty of Technology, Natural Sciences and Maritime Sciences, holds a digital final defence of the doctoral dissertation on «Methane Production from Lignocellulosic Residues».

The trial lecture «Strategies and challenges in bioenergy process development when utilizing syngas in AD-reactors» starts at 0930 and the disputation at 1200 on May 25. 

All interested are welcome to follow the event on Zoom (click on the link that becomes active when the program starts).


Bio-based renewable products can be developed to replace fossil-based products. In this project, as part of the Norske Skog innovation project Pyrogas co-funded by The Norwegian Research Council (EnergyX Programme), lignocellulosic biomass, especially Norway spruce and birch, is examined for its potential in production of biochar for the metallurgical industry and biogas, a renewable fuel.

Pyrolysis, hot water extraction (HWE) and anaerobic digestion (AD) are used in combinations to optimize the carbon utilization of the lignocellulosic biomass. The organic rich liquid streams that are produced from pyrolysis and HWE are examined for their biogas production potential for enhanced carbon recovery of the total process. Hydrolysate has organics that are suitable feeds for AD but undigestible components and inhibitors make this challenging. APL is an even challenging substrate with many toxic components.

The anaerobic digestion of the hydrolysate led to a high methane yield at a good production rate, but both yield and rate were reduced when increasing the HWE temperature influenced by higher inhibitor production during the HWE pre-treatment. The APL methane yield was lower than hydrolysate and more varying.

It was slightly less influenced by the pyrolysis pretreatment temperature but can be improved further by HWE before pyrolysis. Both co-digestion of APL with hydrolysate and individual digestion of the two waste streams was successful and gives more insight into the possibilities of utilizing these organic rich waste streams.