长江上游大中型水库碳排放量估算与分析:以IPCC国家温室气体清单指南为基础

Estimation and analysis of carbon emissions from the large-and medium-sized reservoirs in the upper reaches of Changjiang River:On the basis of the IPCC National Greenhouse Gas Inventory

“双碳”背景下,我国能源结构面临持续转型发展。作为清洁可再生能源,水电开发是近年来长江上游水资源开发利用的重点工作。然而,筑坝蓄水将在一定程度上改变区域碳排放情况。评估水库碳排放量是客观、科学认识水电清洁能源属性的基础,是国家温室气体清单的一个重要组成部分。基于IPCC国家温室气体清单指南层级1(Tier 1)的方法,以长江上游24个中、大型水库为案例,探讨长江上游典型水库生命周期内的碳排放量,并通过蒙特卡洛模拟对估算结果进行不确定性分析及模型参数的敏感性分析。结果显示,24个水库的生命周期碳排放量分布在0.0342~140.59 Tg CO_(2eq)的区间内,总排放量达到264.05 Tg CO_(2eq)(其中,CO_(2)排放量占9.12%,CH 4排放量占90.88%),单位发电量的碳排放均值为3.30 g CO_(2eq)/(kW·h)(0.01~17.64 g CO_(2eq)/(kW·h)),最小、最大值分别出现在锦屏二级水库和彭水水库。此外,敏感性分析发现,在模型涉及的参数中,营养程度调整系数的不确定性对最终估算结果的不确定性起主导作用,下游CH 4通量与水库水气界面CH 4通量的比值敏感性最小。研究工作可为后续推广应用IPCC国家温室气体清单提供参考。

The energy structure in China is facing sustainable transformation and development.Hydropower,as a source of clean energy,is widely built up in the upper reaches of Changjiang River drainage basin where great terrain differences occurred.However,there is a lack of research on the greenhouse gases(GHGs)emissions of reservoirs in the hydropower life cycle in a specific region,and the inconsistent estimation methods lead to poor comparability of the estimation results.Based on Tier1 in the IPCC National Greenhouse Gas Inventories,this study explores the life cycle GHGs emissions of 24 medium and large reservoirs in the upper reaches of Changjiang River,and conducts uncertainty and sensitivity analysis of model parameters through Monte Carlo simulation.The results show that the average carbon emissions of the 24 reservoirs are distributed in the range of 0.0342-140.59 Tg CO_(2eq).The total carbon emissions reached 264.05 Tg CO_(2eq)(CO_(2) emissions accounted for 9.12%,CH 4 emissions accounted for 90.88%).The average carbon emission per unit power generation is 3.30 g CO_(2eq)/(kW·h)(0.01-17.64 g CO_(2eq)/(kW·h)),and the minimum and maximum values appeared in JinpingⅡReservoir and Pengshui Reservoir,respectively.In addition,sensitivity analysis found that among the parameters involved in the model,the nutritional adjustment coefficient played a leading role in the uncertainty of the final estimation results,while the ratio of total downstream flux of CH 4 to the flux of CH 4 from a reservoir s surface to the atmosphere had the weakest sensitivity to results.This provides good guidance to select parameters when using this model and to carry out sampling detection in the future.