The depletion of fossil-based fuels, fluctuating fuel market, and environmental deterioration demand an aggressive approach towards the advancement of renewable energy technologies. By the time reliable technology for a clean and abundant energy supply is established, existing sources must be economized. Biomass gasification is the way forward in that direction. CFD modeling shows promise in the development of advanced gasification systems. A simplified 3D CFD model of a downdraft gasifier is developed to investigate the effect of gasifying agent composition on the quality of syngas. Simulation results are compared with published experimental data and found to be in reasonably good agreement. Mixing CO₂ with a gasification agent is also investigated as a possible carbon capture and utilization (CCU) strategy. An air-steam mixture is used as a base-case gasification agent. Firstly, the effect of air-to-steam ratio on syngas composition is investigated. Secondly, the effect of oxygen and mixing CO₂ with a gasification agent is investigated in two separate cases. A 50%-50% air-steam mixture is found to produce the best quality syngas. Oxygen is found to have a negligible impact on the quality of syngas. The air-steam-CO₂ = 23%-50%-15% mixture is found to be optimum regarding syngas quality.

Biomass is a renewable energy source with great potential worldwide and in the European Union. However, valorization is necessary to turn many types of waste biomass into a tradable commodity that has the potential to replace coal in power plants without significant modifications to firing systems. Mild pyrolysis, also known as torrefaction, is a thermal valorization process of low-quality biomass that could be suitable for such a purpose. In this work, typical Spruce-Pine-Fir residues from a sawmill were tested in terms of the explosion and flame propagation properties. The ISO 1 m³ dust explosion vessel was used, with a modified and calibrated dust dispersion system that could cope with very coarse particles. The deflagration index, K_st, was higher for the torrefied sample, with a peak at 36 bar m/s compared with 27 for the raw biomass. The peak flame speeds were similar for both samples, reaching 1 m/s. The peak P_max/P_i was between 7.3 and 7.4 bar for both untreated and torrefied biomass. The mechanism for coarse particle combustion is considered to be influenced by the explosion-induced wind blowing the finer fractions ahead of the flame, which burns first, subsequently devolatilizing the coarser fractions.

This study examines the sustainable decomposition reactions of benzene using non-thermal plasma (NTP) in a dielectric barrier discharge (DBD) reactor. The aim is to investigate the factors influencing benzene decomposition process, including input power, concentration, and residence time, through kinetic modeling, reactor performance assessment, and machine learning techniques. To further enhance the understanding and modeling of the decomposition process, the researchers determine the apparent decomposition rate constant, which is incorporated into a kinetic model using a novel theoretical plug flow reactor analogy model. The resulting reactor model is simulated using the ODE45 solver in MATLAB, with advanced machine learning algorithms and performance metrics such as RMSE, MSE, and MAE employed to improve accuracy. The analysis reveals that higher input discharge power and longer residence time result in increased tar analogue compound (TAC) decomposition. The results indicate that higher input discharge power leads to a significant improvement in the TAC decomposition rate, reaching 82.9%. The machine learning model achieved very good agreement with the experiments, showing a decomposition rate of 83.01%. The model flagged potential hotspots at 15% and 25% of the reactor’s length, which is important in terms of engineering design of scaled-up reactors.

Brewers’ Spent Grain is a by-product of the brewing process, with potential applications for energy purposes. This paper presents the results of an investigation aiming at valorization of this residue by torrefaction, making product for two purposes: a solid fuel that could be used for generation of heat for the brewery and a colouring agent that could replace colouring malt for the production of dark beers. Decreased consumption of malt for such purposes would have a positive influence on the sustainability of brewing. Torrefaction was performed at temperatures ranging between 180 °C and 300 °C, with a residence time between 20 and 60 min. For the most severe torrefaction conditions (300 °C, 60 min), the higher heating value of torrefied BSG reached 25 MJ/kg. However, the best beer colouring properties were achieved for mild torrefaction conditions, i.e., 180 °C for 60 min and 210 °C for 40 min, reaching European Brewery Convention colours of 145 and 159, respectively. From the solid fuel properties perspective, the improvements offered by torrefaction in such mild conditions were modest. Overall, the obtained results suggest some trade-off between the optimum colouring properties and optimum solid fuel properties that need to be considered when such dual-purpose torrefaction of BSG for brewery purposes is implemented.

This comprehensive review paper offers a multifaceted examination of non-thermal plasma applications in addressing the complex challenge of tar removal within biomass-oriented technologies. It begins with a concise introduction to the research background, setting the context for our exploration. The research framework is then unveiled, providing a structured foundation for understanding the intricate dynamics of plasma–tar interactions. As we delve deeper into the subject, we elucidate the reactivity of tar compounds and the transformation of alkali metals through plasma-based methodologies, essential factors in enhancing product gas quality. Through an array of empirical studies, we investigated the nuanced interactions between plasma and diverse materials, yielding crucial insights into plasma kinetics, modeling techniques, and the optimization of plasma reactors and processes. Our critical review also underscores the indispensable role of kinetic modeling and simulation in advancing sustainable green energy technologies. By harnessing these analytical tools, researchers can elevate system efficiency, reduce emissions, and diversify the spectrum of available renewable energy sources. Furthermore, we delve into the intricate realm of modeling plasma behavior and its intricate interplay with various constituents, illuminating a path toward innovative plasma-driven solutions. This comprehensive review highlights the significance of holistic research efforts that encompass empirical investigations and intricate theoretical modeling, collectively advancing the frontiers of plasma-based technologies within the dynamic landscape of sustainable energy. The insights gained from this review contribute to the overall understanding of plasma technologies and their role in achieving a greener energy landscape.