An inclusive trend study of techno-economic analysis of biofuel supply chains.

Biofuels have gained much attention as a potentially sustainable alternative to fossil fuels to tackle climate change and energy scarcity. Hence, the increasing global interest in contributing to the biofuel supply chain (BSC), from biomass feedstock to biofuel production, has led to a huge amount of scientific production in recent years. In this vein, techno-economic analysis (TEA) of biofuel production to estimate total costs and revenues is highly important for transitioning towards a bioeconomy. This research aims to provide a comprehensive image of the body of knowledge in TEA evolution within the BSC domain. To this end, a systematic science mapping analysis, supported by a bibliometric analysis, is carried out on 1104 articles from 1986 to 2021. As a result, performance indicators of the scientific production within the target literature are presented to explain how this literature has evolved. Besides, thematic trends and conceptual structures of TEA of biofuel production are discovered. The results show that (i) biofuel production and consumption need promotion through tax measures and price subsidies, (ii) the development of cost-competitive algal biofuels has faced many challenges over recent years, and (iii) TEA of algal biofuels to identify commercial improvements and increase the economic feasibility is still lacking, which calls for more in-depth investigations. Consequently, current challenges and future perspectives of TEA in the BSC domain are rendered. The provided insights enable researchers and decision-makers involved in BSCs to (i) capture the most influential contributors to the field and (ii) identify major research hotspots and potential directions for further development.

Highly digestible nitrogen-enriched straw upgraded by ozone-urea pretreatment: Digestibility metrics and energy-economic analysis.

Ozone is a powerful oxidative gas widely used as a green pretreatment to enhance the delignification of cereal straws. Urea pretreatment can enrich straws with nitrogen to make them more accessible to anaerobic microorganisms. This study aimed to evaluate the effect of ozone-urea pretreatment on the digestibility of wheat straw (i.e., physicochemical, nitrogen enrichment, gas production, nutritional value, and surface chemistry). The results of ozone-urea pretreatment were compared with non-pretreated, ozone-pretreated, and urea-pretreated samples. This pretreatment method outperformed the other methods in terms of digestibility metrics. The ozone-urea pretreatment resulted in a 50% reduction in lignin, a 4.2 times increase in crude protein, a 22.5% increase in bonded organic-N, a 2 times increase in 24 h-gas production, and a 43.67% increase in total digestible nutrients compared to the non-pretreated sample. Based on the total digestible nutrients index, one-tonne ozone-urea-pretreated straw would be 70.6 USD cheaper than the non-pretreated one.

A framework for evaluating county-level non-point source pollution: Joint use of monitoring and model assessment.

It is believed that non-point source (NPS) pollution threatens the regional environment. Because of the disconnection between the hydrological scale and the administrative scale of implementing feasible management policies in existing research, watershed-based management measures have limited application in current NPS control. In this study, a framework for county-level monitoring and evaluation is proposed, which contains a cascade monitoring scheme and an adaptable assessment scheme. The cascade monitoring scheme is based on the principle of "pollution source-transport pathways-receiving waters" layout method and the adaptable assessment scheme makes full use of monitoring data in the model. A set of processes was designed to monitor and assess county-level NPS pollution, from the initial step of county basic situation investigations to the final step of NPS pollution assessment. Two schemes are included in the process to improve the feasibility of the results. Here, the importance of the joint use of monitoring and simulation for environmental policy and management is stressed, and focus is on the characteristics of administrative boundaries. A case study involving Nanle County is presented, and a detailed layout scheme and the assessment results are given in this paper.