Biomethane, as a potential substitute for natural gas, reduces the use of fossil-based sources, promoting bioenergy applications. Biomethane for energy use can be produced using a variety of biomass types and technologies. Biomethane from farmland crops is currently produced by anaerobic digestion (AD) of energy crops, which is a biological treatment of organic material resulting in biomethane and digestate. Recently, thermochemical conversion technologies of biomass to biomethane have gained attention. Pyrolysis is a thermochemical process whereby woody biomass is converted to fuel gas and biochar. This study assessed the land use efficiency of producing biomethane through a maize-based AD system compared with switching to a willow-based biomethane system using pyrolysis as an emerging technology. The energy performance and climate impact of the two pathways were assessed from a land use perspective, using life cycle assessment methodology. The entire technical system, from biomass production to delivery of biomethane as the end product, was included within the analysis. The study also investigated how the climate impact was affected when biochar was applied to soil to act as a soil amendment and carbon sequestration agent or when biochar was used as an energy source. Pyrolysis of willow had a higher external energy ratio and climate mitigation effect than maize-based AD as a result of lower primary energy inputs and lower methane loss in the pyrolysis process and upgrading units. Furthermore, the biochar from willow pyrolysis, when used as a soil amendment or energy source, contributed significantly to the climate impact mitigation potential in both cases. Substituting fossil gas with biomethane gave a considerable reduction in climate impact in all scenarios, especially in the case of willow pyrolysis. The willow pyrolysis system acted as a carbon sink, resulting in a negative climate impact, counteracting global warming. From a land use perspective, the transition from maize-based AD to a willow-based pyrolysis system for biomethane production could be beneficial regarding the energy performance and climate impact. Application of biochar to the soil in the willow scenario contributed significantly to counteracting emissions of greenhouse gases.

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使用生命周期评估方法探索柳树热解生产生物甲烷的潜力

生物甲烷作为天然气的潜在替代品，减少了基于化石的资源的使用，促进了生物能源的应用。可以使用多种生物质类型和技术来生产用于能源的生物甲烷。目前，农田作物产生的生物甲烷是通过能源作物的厌氧消化（AD）产生的，这是对有机物质的生物处理，产生了生物甲烷和消化物。近来，生物质向生物甲烷的热化学转化技术受到关注。热解是一种热化学过程，可将木质生物质转化为燃气和生物炭。这项研究评估了通过基于玉米的AD系统生产生物甲烷的土地利用效率，与使用热解作为一种新兴技术转换为基于柳树的生物甲烷系统相比。使用生命周期评估方法，从土地利用的角度评估了这两种途径的能源绩效和气候影响。分析包括从生物质生产到生物甲烷作为最终产品的交付的整个技术系统。该研究还调查了当将生物炭用作土壤改良剂和固碳剂或将生物炭用作能源时，如何影响气候影响。柳树的热解比基于玉米的AD具有更高的外部能量比和气候缓解效果，这是由于在热解过程和升级装置中较低的一次能量输入和较低的甲烷损失所致。此外，柳树热解产生的生物炭在用作土壤改良剂或能源时，在这两种情况下，都对缓解气候变化的潜力做出了重大贡献。在所有情况下，特别是在柳树热解的情况下，用生物甲烷代替化石气体可大大降低气候影响。柳树热解系统充当碳汇，对气候造成负面影响，抵消了全球变暖。从土地利用的角度来看，从玉米为基础的AD到柳树为生物甲烷生产的热解系统的过渡在能源绩效和气候影响方面可能是有益的。在柳树中，生物炭在土壤中的应用显着有助于抵消温室气体的排放。柳树热解系统充当碳汇，对气候造成负面影响，抵消了全球变暖。从土地利用的角度来看，从玉米为基础的AD到柳树为生物甲烷生产的热解系统的过渡在能源绩效和气候影响方面可能是有益的。在柳树中，生物炭在土壤中的应用显着有助于抵消温室气体的排放。柳树热解系统充当碳汇，对气候造成负面影响，抵消了全球变暖。从土地利用的角度来看，从玉米为基础的AD到柳树为生物甲烷生产的热解系统的过渡在能源绩效和气候影响方面可能是有益的。在柳树中，生物炭在土壤中的应用显着有助于抵消温室气体的排放。