Thomas Kohl

• Dr. Sc. (Tech.)
• Technology Director at Andritz

Novel biofuel pathways with increased product yields are evaluated against conventional lignocellulosic biofuel production processes: methanol or methane production via gasification and ethanol production via steam-explosion pre-treatment. The novel processes studied are ethanol production combined with methanol production by gasification, hydrocar...

Biomass fast pyrolysis (BFP) is a promising pre-treatment technology for converting biomass to transport fuel and in the future also for high-grade chemicals. BFP can be integrated with a municipal combined heat and power (CHP) plant. This paper shows the influence of BFP integration on a CHP plant's main parameters and its effect on the energetic...

The goal of biofuel production is to partially replace fossil fuels in energy generation and transport. For the evaluation of biofuel production processes different criteria are applied and usually they include costs, efficiency aspects and emissions. However, evaluation of the energy efficiency of biofuels production is difficult since no general...

In order to react on future expected increased competition on restricted biomass resources, communal combined heat and power (CHP) plants can be integrated with biomass upgrading processes that add valuable products to the portfolio. In this paper, outgoing from a base case, the retrofit integration of production of wood pellets (WPs), torrefied wo...

Waste biomass as a mean for global carbon dioxide emissions mitigation remains under-utilized. This is mainly due to the low calorific value of virgin feedstock, characterized generally with high moisture content. Aqueous processing, namely hydrothermal liquefaction in subcritical water conditions, has been demonstrated experimentally to thermally...

Steel production generates approximately 7% of the global anthropogenic CO2 emissions. Due to the projected growth in demand, this figure can be expected to grow. As modern steel production has been optimized over the last decades close to its thermodynamical limit, further reduction of CO2 emission and energy demand by fine tuning are considered d...

Hydrothermal liquefaction of biomass continues to show promise in experimental and pilot scale tests for carbon partitioning toward desirable multi-phase organic products. Results from a techno-economic investigation are presented for a commercial scale stand-alone plant with primary production of renewable liquid fuels compatible with current tran...

This article presents a summary of the main findings from a collaborative research project between Aalto University in Finland and partner universities. A comparative process synthesis, modelling and thermal assessment was conducted for the production of Bio-synthetic natural gas (SNG) and hydrogen from supercritical water refining of a lipid extra...

The objective of this work is to assess the thermoeconomics of three biomass upgrading processes. The production processes under scrutiny are those for wood pellets, torrefied wood pellets and pyrolysis slurry (a mixture of pyrolysis char and oil). By process simulation, all processes were integrated with a communal combined heat and power plant. T...

The gasification of biomass in supercritical water is an emerging technology which offers the opportunity to produce methane and hydrogen from high-moisture biomass and waste streams. The obstacles of the technology owe to an early development stage but can also be attributed to the mechanically and chemically challenging process conditions (>375 °...

Improving energetic performance is a key factor in making societies more sustainable. One way to analyze energetic performance is to use methods based on the second law of thermodynamics. Exergy analysis is such a method. With exergy analysis thermodynamic losses of the studied system can be found. For a specific process decreasing the exergy losse...

Hydrothermal liquefaction of biomass continues to show promise in experimental scale tests for both, biocrude yield and carbon balance toward desirable organic products. As part of Finland's national drive toward a future bio-economy, a techno-economic investigation was conducted for a 653 MWLHV (15 wt.% solids) Finnish forest residue feedstock und...

Hydrothermal liquefaction of biomass has continued to show promise in experimental scale tests for the production of valorised biocrude, compatible with existing CHP infrastructure. A constrained thermodynamic model is developed to match the recorded mass and energy balances in literature, and depict the solid organic to liquid fuel conversion for...

In order to decrease the rate of reductants originating from fossil sources in iron- and steelmaking, the use of biomass was studied numerically. A biomass pretreatment plant, consisting of a drier and a torrefaction/pyrolysis unit, was integrated with the steel plant, utilizing the off-gas of the hot stoves and blast furnace gas for drying the bio...

Hydrothermal processing of organics, particularly the supercritical water gasification process, has showed potential in lab-scale records to valorize the chemical energy stored in biomass. The technology manipulates the varying thermo-physical properties around the critical point of water to convert and upgrade the organic content, as well as extra...

Enhanced biofuel production routes utilizing separate lignin and carbohydrate processing of lignocellulose are analyzed and compared with two conventional routes; the methanol and methane production via syngas from biomass. The enhanced processes studied are: hydrocarbons production by hydrogenation of biomass based sugars by hydrogen obtained from...

Biomass conversion in supercritical water represents one of the emerging areas of the reaction engineering. Additionally, Supercritical Water Gasification, SCWG, offers great possibilities for new ways of reactors design and operations. Reactive separation processes represent the future in this sense. In our studies experiments were done on SCWG of...

In this work, a mathematical model is introduced that simultaneously solves the mass- and energy balance of the fast pyrolysis process. For the yield calculation, the model uses starting values obtained from the literature. The mass balance is matched by introducing polycyclic aromatic hydrocarbon compounds, which are minimised by applying an optim...

Supercritical water as a process medium for hydrothermal treatment of carbonaceous material has shown an advantageous nature for energetic valorisation. The thermo-physical properties of water around the acute conditions of 22.09 MPa and 374.29˚C (critical point of water) vary significantly and a mixture of both compressible liquid-and gas-like beh...

Hydrothermal processing of biomass, and in particular supercritical water gasification, SCWG, has illustrated the potential to counter technical barriers that continue to face the wide deployment of biomass based energy systems. A conceptual plant flow sheet for SCWG of spirulina algae feedstock is developed on Aspen plus® for synthetic natural gas...

Supercritical water gasification as a mean for hydrothermal processing of biomass, has illustrated the potential to overcome technical barriers that continue to prevent the prevalence of biomass based energy systems. This paper provides a systematic analysis to fill the knowledge gap for upscaling the process from laboratory bench scale to energeti...

Improving energetic performance is a key factor in making societies more sustainable. One way to analyze energetic performance is to use methods based on the second law of thermodynamics. Exergy analysis is such a method. With exergy analysis thermodynamic losses of the studied system can be found. Exergy shows the maximum useful work potential tha...

One of the major advantages of supercritical water gasification (SCWG) of biomass is the possibility to process feedstock with high water content without the need of drying. Regarding the industrial application of the SCWG technology it is clear that heat-recovery and -integration will play a crucial role, as will the applied heat conversion techno...

The gasification of biomass in supercritical water is an emerging technology which offers the opportunity to produce methane and hydrogen from high-moisture biomass and waste streams. The obstacles of the technology owe to an early development stage but can also be attributed to the mechanically and chemically challenging process con-ditions. The s...

Fossil fuels applied in energy generation-, transport- and refinery processes can be replaced by biofuels. This offers plenty processing options for biomass resources such as thermo-chemical. For process evaluation different criteria is applied, usually including costs, energy efficiency and CO2 emission. However, comparative evaluation of the ener...

The use of biofuel as a road transportation fuel is increasing throughout Europe and other industrialized countries to reduce greenhouse gas emissions and to improve the security of fuel supply. Bio-oil produced from biomass pyrolysis is renewable liquid fuel and can also be used for production of chemicals. Upgrading of the bio-oil to transportati...

A prediction for product gases of Jatropha curcas Linn (JCL) oil cake gasified in the entrained flow reactor is studied in this paper. ASPEN PLUS commercial software is used to carry out the simulation using Gibbs free energy minimisation with equilibrium phase. A series of simulations and analyses have been carried out to investigate the compositi...

In order to estimate the heat of condensation of fast pyrolysis product of woody biomass a model to be used in the chemical process simulation software Aspen+ has been developed based on the composition of wood fast pyrolysis product. A simulation model for biomass fast pyrolysis was developed. The results obtained are in good accordance with value...

In order to react on high future biomass prices, communal CHP plants can be integrated with biomass upgrading processes that add valuable products to the portfolio. In this paper, outgoing from a base case, we simulate the retrofit integration of wood fast pyrolysis slurry, torrefied wood pellets and wood pellets production with an existing wood-fi...

This paper investigates the influence of the integration of communal biomass-fired combined heat and power plants with wood-pyrolysis on the plant’s energy balance and product distribution. Further the proposed integration concept’s influence on the environmental performance of the connected district heating network is pointed out. The environmenta...

The objective of the paper is to compare the efficiency of three different biomass-to-liquid systems. For this purpose European standards for energy rating of buildings have been successfully modified and applied to biofuel production. The method compares the primary energy consumption -expressed by primary energy factors- and the fossil CO2 emissi...

This paper gives an estimation of the mass and energy balances of the integration of biomass pyrolysis with a biomass-fired combined heat and power (CHP) plant. It is a status report reflecting ongoing research and is hence not discussing final results. By integrating biomass pyrolysis with a CHP plant the overall efficiency of the plant is estimat...

The objective of this paper is to determine biorefinery concepts producing biofuel that are suitable for integration into combined heat and power plants. The driving force is that the reduction of greenhouse gas emissions in the transportation and energy sector will increase competition in biomasses. It seems that by polygeneration of interstage fu...