Techno-economic assessment of product gas methanation system integrated in biogas plant : Comparative study between biological and catalytic methanation processes
Haho, Oskari (2023)
2023
Ympäristö- ja energiatekniikan DI-ohjelma - Programme in Environmental and Energy Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2023-09-15
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202309088071
https://urn.fi/URN:NBN:fi:tuni-202309088071
Tiivistelmä
The thesis investigated the economics of the methanation process of the product gas of a 1 MW wood gasifier profitability in both biological and catalytic processes in a farm-scale biogas plant. Cost and cost structure of synthetic methane is calculated in several study cases.
The thesis has studied cases, where excess hydrogen from the electrolyser is mixed with the product gas. The calculations include biogas carbon dioxide methanation cost estimations. The electrolyser produces pure oxygen, which is used in the gasifier. The hydrogen is produced at a fixed electricity price in the calculations.
Biological methanation is based on the trickle-bed reactor technology. Biological methanation occurs in thermophilic conditions. The catalytic process utilizes fluidized bed reactor technology in the thesis.
A distribution obligation of road traffic increases the profitability of synthetic methane. A gasifier scale-up from 1 MW size increases the profitability of the methanation process.. Mixing hydrogen into product gas increases the cost of synthetic methane.
The thesis records the lowest synthetic methane production cost at 180.0 C/MWh. The value is achieved through a combined product gas and biogas methanation process in a catalytic reactor. In the thesis calculations, the highest cost is 240 C/MWh, corresponding to product gas methanation in a catalytic reactor.
The technological maturity of the catalytic process is higher. Biological methanation has currently more uncertainties in the process. Based on this work, the choice for methanation technology in a farm environment is fluidized bed catalytic methanation.
The thesis has studied cases, where excess hydrogen from the electrolyser is mixed with the product gas. The calculations include biogas carbon dioxide methanation cost estimations. The electrolyser produces pure oxygen, which is used in the gasifier. The hydrogen is produced at a fixed electricity price in the calculations.
Biological methanation is based on the trickle-bed reactor technology. Biological methanation occurs in thermophilic conditions. The catalytic process utilizes fluidized bed reactor technology in the thesis.
A distribution obligation of road traffic increases the profitability of synthetic methane. A gasifier scale-up from 1 MW size increases the profitability of the methanation process.. Mixing hydrogen into product gas increases the cost of synthetic methane.
The thesis records the lowest synthetic methane production cost at 180.0 C/MWh. The value is achieved through a combined product gas and biogas methanation process in a catalytic reactor. In the thesis calculations, the highest cost is 240 C/MWh, corresponding to product gas methanation in a catalytic reactor.
The technological maturity of the catalytic process is higher. Biological methanation has currently more uncertainties in the process. Based on this work, the choice for methanation technology in a farm environment is fluidized bed catalytic methanation.