Methane, Volume 4, Issue 1 (March 2025) – 7 articles

This study evaluates the energy recovery from biogas generated through the anaerobic co-digestion of the Organic Fraction of Urban Solid Waste (OFUSW) with lime mud (LM). This approach aims to mitigate environmental impacts such as greenhouse gas emissions and pollution while promoting energy recovery for a diversified power matrix. Life cycle assessment (LCA) methodology, in accordance with the NBR ISO 14040 and 14044 standards, was used to compare five scenarios for the disposal of LM. The results highlight that the co-digestion scenario showed significant environmental benefits in 8 out of the 18 categories evaluated, such as reductions in eutrophication, acidification, and climate change. Additionally, the digestate produced helped avoid further environmental impacts. The integration of urban and industrial waste demonstrates the potential to enhance biogas productivity, generate savings for the pulp and paper industry, and promote sustainable practices. The innovation lies in the synergistic use of LM as a co-substrate, improving the efficiency of the anaerobic process and maximizing biogas production. This research provides a solid scientific foundation for decision-making in public policies and industrial practices, positioning itself as a viable and innovative proposal for the integrated management of solid waste and sustainable energy. Full article

This study employs DFT at the APFD/def2-TZVP level, with SMD solvation in THF, to investigate the catalytic activation of methane by [(κ³-CNC)Fe(N₂O)]²⁺ cation complexes. The catalytic mechanism encompasses three key steps: oxygen atom transfer (OAT), hydrogen atom abstraction (HAA), and oxygen radical rebound (ORR). The computational results identify OAT as the rate-determining step, with activation barriers of −10.2 kcal/mol and 5.0 kcal/mol for κ¹-O- and κ¹-N-bound intermediates in the gas and solvent phases, respectively. Methane activation proceeds via HAA, with energy barriers of 16.0–25.2 kcal/mol depending on the spin state and solvation, followed by ORR, which occurs efficiently with barriers as low as 6.4 kcal/mol. The triplet (S = 1) and quintet (S = 2) spin states exhibit critical roles in the catalytic pathway, with intersystem crossing facilitating optimal reactivity. Spin density analysis highlights the oxyl radical character of the Fe^IV=O intermediate as being essential for activating methane’s strong C–H bond. These findings underscore the catalytic potential of CNC-ligated iron complexes for methane functionalization and demonstrate their dual environmental benefits by utilizing methane and reducing nitrous oxide, a potent greenhouse gas. Full article

The effects of milling on the anaerobic degradability of wheat straw and corn stover were investigated. Pretreatment was carried out by an industrial-scale device, able to process over one ton per hour. After 28 days of digestion under mesophilic conditions, the cumulative methane production from the pretreated straw (250 Nm³ t⁻¹ of volatile solids) was 49.2% greater than that from the raw material. Pretreated stover reached a cumulative methane yield of 219.8 Nm³ t⁻¹ of volatile solids, gaining 10.1% as compared to the feedstock. The specific electrical energy requirements for pretreatment were 66.6 kWh t⁻¹ for processed straw and 64.8 kWh t⁻¹ for stover; these consumptions were not significantly different. With reference to biomethane production, the impact of raw material on the production cost decreased from EUR 0.418 Nm⁻³ to EUR 0.328 Nm⁻³ for pretreated straw, whereas it increased by 5.8% for corn stover, whose pretreatment, therefore, was not economically feasible. Full article

In order to solve the wall damage problem of roadways with deep and high stress in methane explosion accidents, mathematical-physical analysis models for the dynamic response damage of roadway walls were established by LS-Dyna software in this paper, and the models were validated to be effective. The roadway wall displacement, stress, and deformation characteristics under the methane explosion impact load were numerical simulated and the response and damage evolution process of the roadway wall was studied. The results indicate that the model established in this study can reflect the dynamic response damage characteristics of the roadway wall. The damage of the roadway wall caused by the methane explosion impact load was mainly concentrated in the methane accumulation section, but the maximum principal stress of the roadway wall near the methane accumulation section was still high, and the damage possibility was also high. The dynamic response damage of the roadway wall decreased with the increase in the distance from the initiation explosion point. The stress response of the curved part of the roadway roof was the most severe, and the stress response of the side part was second to that of the roof. The stress changes at the corners were significant, but the deformation was small. The bottom plate was minimally affected by the methane explosion impact loads. The arch top and two sides of the roadway were first subjected to significant impact, resulting in a high-pressure zone. The peak pressure of the side part was relatively high, and the difference in peak pressure between the corner and the bottom plate was not significant. Full article

Methane is a strong green gas that has higher GWP. Methane emissions, therefore, form one of the critical focuses within climate change mitigation policy. Indeed, the present study represents a very novel analysis of methane emission within the ESG framework by using the data across 193 countries within the period of 2011–2020. Methane reduction on account of ESG delivers prompt climate benefits and thereby preserves the core environment, social, and governance objectives. In spite of its importance, the role of methane remains thinly explored within ESG metrics. This study analyzes how factors like renewable energy use, effective governance, and socioeconomic settings influence the emission rate of the study subject, as many previous ESG studies are deficient in considering methane. By using econometric modeling, this research identifies that increasing methane emissions remain unabated with the improvement of ESG performances around the world, particularly within key agricultural and fossil fuel-based industrial sectors. Renewable energy cuts emissions, but energy importation simply transfers the burdens to exporting nations. It therefore involves effective governance and targeted internationational cooperation, as socioeconomic elements act differently in different developed and developing countries to drive various emission sources. These findings strongly call for balanced, targeted strategies to integrate actions of mitigation into ESG goals related to methane abatement. Full article

Steam reforming is an important industrial process for hydrogen production. Acetone, the by-product of phenol production from cumene peroxidation, is a useful source of hydrogen due to its availability and low value compared to hydrogen fuel. This study aimed to utilize the Gibbs free energy minimization method using the Soave–Redlich–Kwong (SRK) equation of state (EOS) to conduct a thermodynamic analysis of the steam reforming process for pure component acetone. The steam reforming process is temperature dependent, with increasing temperatures leading to higher hydrogen production. Competing reactions, particularly the exothermic reverse water–gas shift, impact hydrogen yields beyond 650 °C. The study identified 600 °C as the optimum temperature to strike a balance between maximizing hydrogen production and minimizing the reverse water–gas shift’s impact. The optimal hydrogen yield (70 mol%) was achieved at a steam-to-oil ratio (STOR) of 12. High STOR values shift the equilibrium of the water–gas shift reaction towards hydrogen production due to increased steam, effectively consuming acetone and favoring the desired product. Atmospheric pressure is optimum for hydrogen production because the equilibrium of gas phase reactions shifts in favor of the lighter components at lower pressures. Full article

The evaluation of measurement uncertainty of natural gas properties calculated from composition data are an essential aspect of fiscal metering in the trade of natural gas. For conformity assessment, and in gas allocation, it is essential to have a reliable value for the uncertainty. This need is also reflected in, e.g., ISO 6976, the standard for computing natural gas properties, which follows the requirements of the “Guide to the expression of uncertainty in measurement” much more closely. Normalised compositions and their associated standard uncertainties do not suffice for this purpose. A novel algorithm is provided to recover these correlations from the normalised fractions and associated standard uncertainties, enabling the industry work with the data already stored in their repositories. The standard uncertainties are reproduced within 2%, which is acceptable for uncertainty calculations. The correlation coefficients obtained from the recovery algorithm agree with the ones obtained by normalisation. Full article