Naslov
The role of biomass and biofuels in the energy transition – a holistic interdisciplinary approach to sustainable anaerobic digestion
(The role of biomass and biofuels in the energy transition – a holistic interdisciplinary approach to sustainable anaerobic digestion)

Autori
Bedoić, Robert

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Fakultet strojarstva i brodogradnje

Mjesto
Zagreb

Datum
19.01

Godina
2022

Stranica
317

Mentor
Pukšec, Tomislav ; Čuček, Lidija

Ključne riječi
Biomass, biofuels, anaerobic digestion, renewable energy sources, chemical kinetics, geospatial availability, environmental impacts.

Sažetak
This doctoral dissertation evaluated the use of sustainable biomass sources (agri-food waste and residues, and industry streams) in anaerobic digestion with the goal of replacing maize silage in a large-scale biogas production and investigated alternative pathways of biogas utilisation incorporated in energy systems operating with high share of renewable energy sources. The methods applied in the research included elements of chemical and mechanical engineering in order to create a holistic approach that could be applicable to various biogas plant cases. Experimental investigations showed the biogas yield of residue lignocellulosic biomass of 0.192-0.275 Nm3 /kgTS, and bulk food waste of 0.252-0.566 Nm3 /kgTS. Meat and bone meal and wastewater sludge were shown to be co-substrates with antagonistic effect in biogas production, however they increased the reaction rate of overall degradation. Pyrolysis of digestate showed lower energy requirements and higher biochar yield (38%) compared to direct pyrolysis of lignocellulosic biomass (24%). The gate fee business model for receiving biodegradable waste and the implementation of new technologies, namely biogas upgrading, are the most likely options for biogas plants in the future. A robust mathematical model of power-to-gas integration showed that the installation of 18 MWel of wind and 9 MWel of photovoltaics with an additional import of 16 GWhel from the grid could produce 36 GWh of renewable methane which could be economically competitive with natural gas if the feedstock gate fee in the proposed system was -120 €/t. Geospatial availability of an energy potential of biogas production from examined feedstocks, combined with Life Cycle Assessment of the alternative biogas utilisation pathways created the synergistic effects in terms of reduced environmental burdens by 4-36 times compared to the current operation. Based on the applied methods and outcomes of the doctoral thesis, the research hypothesis “Applying holistic approach on biogas plants, both on the production and utilisation side, can increase economic profitability and environmental benefits over current subsidised operation” was tested and confirmed. The economic feasibility of biogas plants after exiting subsidy schemes will include the implementation of the gate fee business model for substrates, new investments in biomass pretreatment lines, increase of on-site biogas storage capacity and additional investments in renewable methane production system, primarily biomethane. Environmental burdens of such actions will be reduced through a contribution of biowaste management on urban and rural level, combined with the utilization of biogas for production of biomethane as a replacement to natural gas.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

POVEZANOST RADA