从水库温室气体研究到水电碳足迹评价:方法及进展

From reservoir greenhouse gas emissions to hydropower carbon footprint:methodology and advances

当前,围绕水库温室气体净排放量评估、水电碳足迹评价等方面,仍存在一些不确定或模糊的地方,制约了水电行业开展温室气体核算与管理。对此,本文首先梳理了水库修建及运行在“淹没、阻隔、重建、消纳”等四个方面对温室气体通量产生的影响。结合政府间气候变化委员会提出的概念性框架,探讨了水库温室气体净排放量评估的科学内涵与尚待解决的关键问题,提出了对水库蓄水前后温室气体通量变化评估的技术路径。之后,本文提出了水电碳足迹是指工程项目生命周期内各种人类活动所产生的二氧化碳当量(CO_(2eq))排放总量。综述了全球范围内水电碳足迹评价案例,认为水利水电工程项目的生命周期涵盖项目前期准备、施工建设、运营维护与拆除恢复等四个阶段,但当前在碳足迹评价方法、系统边界划定、评价结果的解读与使用等方面仍尚未有更明晰、规范化的答案。未来,建议进一步加快水库温室气体源汇变化监测评估与水电碳足迹评价的标准体系建设;深化水库碳循环与温室气体通量的基础研究,支撑水库温室气体净排放量评估;完善水电生态环境综合绩效管理体系,创新水电企业温室气体管理制度;积极推动水电在应对气候变化与“双碳目标”实现路径中找准定位、突破创新。

At present,there are still uncertainties and ambiguous aspects in the evaluation of the net green⁃house gas(GHG)emissions of reservoirs and the carbon footprint of hydropower.To this end,this paper firstly illustrated that reservoir construction and operation would regulate GHG emissions through the four ef⁃fects,i.e.,inundation,obstruction,reconstruction,and consumption.Following the conceptual framework proposed by the Intergovernmental Panel on Climate Change,the paper discussed the scientific connotation and existing questions in the evaluation of reservoir net GHG emissions.The technical approach to evaluate pre and post-impoundments GHG emissions of the reservoir was also suggested.In addition,it is clear that hydropower carbon footprint refers to the total GHG emissions,in terms of carbon dioxide equivalents(CO_(2eq)),from all anthropogenic activities during the life cycle of the hydropower project.After a review of global cases,it is considered that the life cycle of a hydropower project should include four phases,i.e.,preparation,construction,operation and maintenance,and decommissioning.Yet,there need more research and applications to answer the questions on methodology development,system boundary,and interpretation of hydropower carbon footprint.Soon,it suggests setting up the standard system for monitoring and evalua⁃tion of reservoir GHG emissions,as well as the assessment of hydropower carbon footprint.Basic scientific research on carbon cycling and carbon fluxes in reservoirs needs to be deepened to support the evaluation of reservoir net GHG emissions.The innovation in the carbon management system is suggested to be based on the improvement of the eco-environmental performance management system of hydropower enterprises.Further activities are required to help the hydropower industry to find the right position and make break⁃throughs and innovations in the path of mitigating climate change and achieving the"double carbon goal".