Biomass wastes are abundantly available, yet leveraging these resources for large-scale green energy production requires a comprehensive and strategic evaluation. In this study, an environmentally sustainable and economically viable gasification process for generating pure hydrogen gas from waste biomass was developed. Switchgrass was combined with two co-feeds: low-density polyethylene (LDPE) and high ash coal to improve hydrogen production efficiency. Two process configurations for biomass gasification/co-gasification were investigated: (1) baseline scenario without addition of key units towards sustainability, including carbon-capture (CC), waste heat recovery (WHR) and in-plant power & steam generation (PSG), and (2) integrated scenario with the addition of CC, WHR and PSG. The integrated gasification scenario achieved over 99 % hydrogen purity and high carbon capture efficiency, leading to negative carbon emissions of –323.55, −465.84, and −68.28 kg CO2 eq. for biomass, biomass-LDPE and biomass-coal gasification, respectively. Besides this, integrated scenarios also displayed negative emissions in most of the other impact categories like ecotoxicity, acidification, eutrophication and many more. The corresponding net present value (NPV) for biomass, biomass-LDPE and biomass-coal gasification integrated scenario was $69.7 million, $108 million, and $76.4 million, respectively. The results indicate that biomass co-fed with LDPE in integrated gasification scenario represents the most environmentally and economically sustainable case with the highest hydrogen production, lowest environmental emissions and highest economic returns. It was also shown that process energy requirements were the key driver of environmental emissions and production costs. This research provides a comprehensive evaluation framework for waste-to-hydrogen technologies by identifying critical process hotspots and necessary policy measures for large-scale implementation of sustainable hydrogen.

中文翻译：

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生物质共气化生产负碳氢气的工艺优化和环境经济评估


生物质废物资源丰富，但利用这些资源进行大规模绿色能源生产需要进行全面的战略评估。在这项研究中，开发了一种环境可持续且经济可行的气化工艺，用于从废弃生物质中产生纯氢气。柳枝稷与两种辅助原料相结合：低密度聚乙烯 （LDPE） 和高灰分煤，以提高制氢效率。研究了生物质气化/共气化的两种工艺配置：（1）没有增加关键单位以实现可持续性的基线情景，包括碳捕获（CC）、废热回收（WHR）和厂内电力和蒸汽产生（PSG），以及（2）增加了CC、WHR和PSG的综合情景。综合气化方案实现了超过 99% 的氢气纯度和高碳捕获效率，导致生物质、生物质-LDPE 和生物质-煤气化的负碳排放量分别为 -323.55、-465.84 和 -68.28 kg CO2 当量。除此之外，综合情景还在大多数其他影响类别中显示负排放，如生态毒性、酸化、富营养化等等。生物质、生物质-LDPE 和生物质-煤气化综合方案的相应净现值 （NPV） 分别为 6970 万美元、1.08 亿美元和 7640 万美元。结果表明，在综合气化情景中，生物质与 LDPE 共进料代表了最具环境和经济可持续性的情况，具有最高的氢气产量、最低的环境排放和最高的经济回报。研究还表明，工艺能源需求是环境排放和生产成本的关键驱动因素。 本研究通过确定大规模实施可持续氢的关键工艺热点和必要的政策措施，为垃圾制氢技术提供了全面的评估框架。