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.

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 paper describes a series of experiments performed to study the explosion characteristics of propanol isomer (1-propanol and 2-propanol)–air binary mixtures. The experiments were conducted in two different experimental arrangements—a 0.02 m³ oil-heated spherical vessel and a 1.00 m³ electro-heated spherical vessel—for different equivalence ratios between 0.3 and 1.7, and initial temperatures of 50, 100, and 150 °C. More than 150 pressure–time curves were recorded. The effects of temperature and test vessel volume on various explosion characteristics, such as the maximum explosion pressure, maximum rate of pressure rise, deflagration index, and the lower and upper explosion limits were investigated and the results were further compared with the results available in literature for other alcohols, namely methanol, ethanol, 1-butanol, and 1-pentanol. The most important results from evaluated experiments are the values of deflagration index 89–98 bar·m/s for 2-propanol and 105–108 bar·m/s for 1-propanol/2-propanol–air mixtures. These values are used to describe the effect of isomer blends on a deflagration process and to rate the effects of an explosion.

The process of gasification is well-known; however, to this day, the applications of such facilities, especially off-grid small-scale units for direct electricity and char production, are scarce. In this study, an off-grid fixed bed downdraft gasification unit is studied from the gaseous/solid product character perspective. This unit represents a possible solution for the emerging call for sustainable decentralised energy sources. Softwood chips were utilised in this study, and their conversion into synthetic gas (direct electricity supply) and solid biochar was observed and analysed. The results show promising values of synthetic gas for potential utilisation in different applications outside the direct combustion process, such as microbial syngas fermentation, with a lower heating value equal to 6.31 MJ·m-3. It appears that during the steam activation process of biochar, both high-quality off-gas of more than 70%vol. H2 (excluding N2) and activated carbon of a specific surface area of 565.87 m2·g-1 can be collected. Further investigations have revealed specific degradation of chemical bonds and material morphology changes during steam gasification. The microporous structure and high specific surface area of the material make it an attractive material for further development as an adsorbent in sorption cooling devices. Therefore, the waste generated within the gasification process is minimised, and the potential of the obtained products will be valued in favour of the sustainability of the remote locations.