基于能值分析的生物质能-碳捕集与封存技术的可持续性研究

Sustainability evaluation of biomass energy carbon capture and storage technology based on emergy analysis

生物质能-碳捕集与封存(Bioenergy with Carbon Capture and Storage,BECCS)是一种应对气候变化的重要负排放技术。然而,目前学者对于该技术的可持续性应用仍存在争议。能值分析是一种能有效评估系统可持续性的量化方法,能够对系统的资源效率、环境影响和经济效益进行综合考量,进而全面反映系统的可持续发展水平。对8种典型的生物质发电系统,即有/无碳捕集与封存(Carbon Capture and Storage,CCS)的生物质直燃发电、生物质掺烧发电、生物质整体气化循环发电以及2种新型BECCS展开能值分析,选取能值产出率、环境负载率、可持续性指数等典型能值指标和碳排放指标对系统展开对比评价。结果显示,生物质发电系统的CO_(2)净排放量远低于煤基发电系统,耦合CCS后可实现负排放效益;生物质发电系统具有较低的环境负载率(ELR<2)和较高的可持续性指数(ESI<5.5),综合效益表现较优,长期可持续。此外,系统可持续性还与国家政策和生物质供应有关。敏感性分析表明,制定合适的激励政策,合理规划电厂选址以确保稳定充足的生物质供给,是提高系统可持续性的重要途径。

Emergy analysis is used to evaluate the sustainability of eight typical biomass power generation systems in this paper.Based on thermodynamics and general system theory,emergy analysis can be defined as the total energy required to make a product or support a process,directly or indirectly.Emergy analysis is an effective quantitative method that can evaluate the sustainability of the system.In this paper,eight typical biomass power generation systems(biomass direct-fired power generation,biomass co-fired power generation,biomass-based integrated gasification combined cycle,and two new BECCS systems)are analyzed.And emergy transformity,emergy yield rate,environmental loading rate,emergy sustainability index,and CO_(2) emission indicators are selected to compare and evaluate the systems.The results show that the net CO_(2) emission of biomass power generation systems is much lower than that of coal-based power generation systems,and the negative emission benefits can be realized after coupling CCS;Biomass power generation systems have lower environmental loading rate(ELR<2)and higher emergy sustainability index(ESI<5.5).Therefore,their comprehensive benefits are excellent and they are sustainable in the long run.Besides,there is a certain positive correlation between the sustainability of the system and national policies,such as carbon tax,and feed-in tariff subsidies.And the deployment of BECCS is more affected by the carbon tax.When no carbon tax is levied,coupling CCS reduces the ESI of each system by more than 31.1%;When the carbon tax exceeds 0.456 yuan/kg,the sustainable advantage of BECCS is relatively obvious.In addition,the research finds that rational planning of power plant site selection to ensure a stable biomass supply is an effective way to improve the ESI of the system.In a word,biomass power generation system has great development potential,which should attract the attention of researchers.