Emergy analysis of agricultural waste biomass for energy-oriented utilization in China: Current situation and perspectives.

Agricultural waste biomass (AWB) is becoming a significant sustainable alternative for fossil fuels. Emergy analysis (EmA) is a promising methodology that provides a uniform standard to assess simultaneously the environmental load and economic returns of a system. Relevant studies on the assessment of AWB energy-oriented utilization by EmA are attracting researchers' attention worldwide. Therefore, this paper aimed to comprehensively review state-of-the-art applications of the EmA for AWB energy-oriented utilization systems. Results indicated that there were limitations and challenges in the application of single EmA. Importantly, the boundary of AWB energy-oriented utilization systems in the application of EmA was not unified, leading to poor comparability of the impact results. Although the effect of policies has a significant influence on the application and promotion of AWB energy-oriented utilization, the EmA method can hardly reflect the effect of policies. Therefore, there is a need in combination with other methods to optimize the EmA, thus providing comprehensive guidance for decision-makers. Finally, based on these, some feasible suggestions especially to (1) further promote the application and (2) development of this research field were presented. It is hoped that this work could support the proper evaluation and further optimization of AWB energy-oriented utilization systems.

Hydrothermal oxygen uncoupling of high-concentration biogas slurry over Cu-α-Fe2O3·α-MoO3 catalyst.

A hydrothermal oxygen uncoupling (HTOU) method which combines aqueous phase reforming (APR) and oxygen uncoupling was proposed to treat biogas slurry (BS). Based on Le Chatelier's principle, this novel approach was constructed and realized by Cu-α-Fe2O3·α-MoO3 catalyst with van der Waals heterojunction-redox property. Additionally, the catalyst was synthesized by integrating a simple one-pot sol-gel method and thermal hydrogenating. Results indicated that the optimal removal efficiencies of non-purgeable organic carbon (NPOC) (76.29%), total nitrogen (TN) (45.56%), and ammonia nitrogen (AN) (29.03%) were achieved on the Cu-α-Fe2O3·α-MoO3 catalyst at 225.00 °C for 30.00 min, respectively. The significant performance of Cu-α-Fe2O3·α-MoO3 could be attributed to three aspects. (1) The α-MoO3 nanosheets with van der Waals heterostructures obtained at the calcination temperature of 600.00 °C, which can provide the superior performance of APR for hydrogen generation. (2) The adsorbed oxygen species were eliminated by thermal hydrogenating which had a surface passivation effect. (3) The effect of oxygen uncoupling in the lattice oxygen and gaseous oxygen release reaction was beneficial to the degradation of organic matter. Moreover, the reuse of catalysts studies further revealed that the deactivation of catalysts originated from carbon deposition of aromatic polymers and heavy metals oxides pollution. Overall, these findings disclosed that the HTOU could be a promising alternative to the treatment of high-concentration organic wastewater.