Various means for enhancing hydrogen content in the syngas from gasification of solid biomass in fluidized-bed reactors were investigated in this study. Steam or oxygen-rich gas can be supplied as gasification medium, to improve the syngas characteristics. Alternatively, a so-called “indirect gasification technology” realizes the thermo-chemical conversion processes in dual reactors, respectively, for combustion and gasification, where gaseous streams in between are separated while solid materials are circulated through. Hence, with air as oxidant for combustion this system features the advantage of producing nearly nitrogen-free syngas. Baseline experiments were firstly carried out to identify performance features; then, parametric studies were conducted and positive trends for enhancing hydrogen generation via biomass gasification were revealed. Moreover, hydrodynamic characteristics in dual reactors were comprehensively envisaged in the cold-flow models to facilitate subsequent investigation into thermo-chemical processes. The experimental results indicated that the circulation mass of the bed material driven by the operating air exceeded the design value, which gave a comfortable safety factor of the engineering design. In addition, the average pressure distribution measured by the cyclic operation of the system was similar to that of the published literature. Based on the experimental results of the cold model, the suggestions of the operating tests in the hot model were addressed. Further efforts will be pursued to establish databases for clean energy and carbon abatement technologies.

This study investigated the optimal proportion of biochar derived from pinewood pellets (PW) and coke as reducing agents for the carbothermal reduction of iron ore at high temperatures. Thermogravimetric analysis, elemental analysis, X-ray fluorescence, and scanning electron microscopy were used to characterize the raw materials. To determine the effect of biochar proportion on reduction efficiency, presented as metallization, metallized pellets were subjected to chemical analysis, including total iron (T.Fe) analysis, metallic iron (M.Fe) analysis, and residual Fe₂O₃ and FeO analysis. The results indicated that the addition of biochar derived from PW, with coke as a reducing agent, considerably increased the efficiency of carbothermal reduction. Optimal reduction conditions were established at a reduction temperature of 1300 °C and a holding time of 20 min, with 20% coke and 80% pinewood char. In summary, biochar derived from PW can be used as an alternative to coke as a reducing agent in the iron reduction process. In addition, biomass can be used as a reducing agent to mitigate carbon consumption by reducing the amount of coke required in iron production.

With recent increases in environmental awareness, the circular economy concept, which involves turning waste into usable products, has gradually become widely accepted. Spent mushroom substrate (SMS) is an agricultural waste that lacks recycling channels in Taiwan. This study explored the feasibility of simultaneously recycling two completely different types of waste: spent mushroom substrate (SMS), an agricultural waste, and electric-arc furnace dust (EAFD), an industrial waste. Specifically, SMS was used to replace metallurgical coke as a reducing agent for EAFD, which underwent carbothermic reduction to recycle valuable metallic Zn. The results showed that if SMS and EAFD were mixed at a C/O ratio of 0.8, the degree of Zn removal achieved 95% at 1100 °C, which is 150 °C lower than the reduction temperature of the EAFD-coke mixture (due to volatile matter (VM) in SMS). For the reduction of ZnO in EAFD, with the assistance of VM in SMS, the C/O ratio can be decreased from 0.8 to 0.16 at 1300 °C, achieving a high degree of Zn removal over 95%. In addition, the torrefaction of SMS increased the fixed carbon content and improved the Zn productivity at the same C/O ratio, reaching almost the same productivity as the coke sample (SMS torrefaction = 500 °C, C/O = 0.8, reduction = 1200 °C, Zn removal~99%). Finally, CO₂ emission reductions from the use of SMS were also estimated.

Agricultural crop residue burning is a major driver of seasonal PM2.5 pollution and greenhouse gas (GHG) emissions in Northern Thailand. This study quantified GHG emissions from the open burning of rice, maize, and sugarcane residues across six provinces (Chiang Mai, Mae Hong Son, Lampang, Uttaradit, Nakhon Sawan, and Kamphaeng Phet) from 2019 to 2024 using the 2006 IPCC emission methodology. Spatiotemporal patterns of fire hotspots were characterized using MODIS and VIIRS satellite data, combined with kernel density estimation (KDE) and land-use classification in ArcGIS Pro. Total non-CO₂ GHG emissions (CH₄ and N₂O, expressed as CO₂-eq using GWP100 from IPCC AR5) over the six years totaled 2,599,551 tCO₂-eq, with major rice contributing the largest share (35%), followed by sugarcane (24%), second rice (21%), and maize (20%). Nakhon Sawan was the leading emitter (41%), reflecting its extensive rice and sugarcane cultivation. Pearson correlation analysis revealed consistently positive relationships between daily fire hotspot counts and PM2.5 concentrations (r = 0.30–0.84), with the strongest correlations observed in Mae Hong Son, where basin topography traps pollutants. Time-series analysis confirmed pronounced seasonal PM2.5 peaks that exceeded Thailand’s 24-h NAAQS limit (37.5 μg/m³) by 7–9 times in severe years. Biochar production via pyrolysis was evaluated as a zero-burning alternative, with an estimated annual carbon sequestration potential of 2.3–3.5 million tCO₂-eq, substantially exceeding emissions from open burning. These findings indicate that crop-residue valorization options—including biochar production, composting, and biochar co-compost—could theoretically offset agricultural GHG emissions and reduce field-burning PM2.5 emissions in Northern Thailand. However, the realized mitigation will depend on (i) verification of biochar long-term stability in tropical Thai soils through dedicated in situ trials, (ii) economic incentives that offset biochar production costs of approximately 1500–3500 THB per tonne, and (iii) integration within a policy mix that combines burning bans, mechanization support, and farmer extension services. Without these enabling conditions, biochar should be regarded as a future-perspective option rather than an immediately deployable solution.