基于全生命周期的地热发电系统环境影响评价

为明确不同类型地热发电系统“获取、转化”环节的钻井、建设、运行、退役等不同过程对地热发电系统的环境影响贡献,本文建立了基于热力学优化模型的闪蒸/双工质地热发电系统全生命周期环境影响评价模型。进而,选取西藏羊八井、广东丰顺、华北油田及青海共和四种典型地热热储,整理和收集了我国地热发电系统的环境影响全生命周期环境影响清单,分析了地热发电站六个不同过程对三个主要环境影响潜值评价指标：酸化潜值、富营养化潜值和全球变暖潜值的影响规律。发现钻井完井过程分别平均占到地热电站酸化潜值、全球变暖潜值和富营养化潜值的46.28%、45.90%和27.52%,地下系统和地上系统的环境影响贡献相当；地热梯度与地热电站的全生命周期环境影响潜值有着负相关关系,梯度越大,环境影响潜值越低。。

Environmental impact assessment of geothermal power generation system based on life cycle assessment

In order to clarify the contribution of drilling, construction, operation and decommissioning of different types of geothermal power generation systems to the environmental impact of geothermal power generation systems, a life cycle environmental impact assessment model of flash/duplex geothermal power generation systems based on thermodynamic optimization model is established. Furthermore, four typical geothermal reservoirs, Yangbajing in Tibet, Fengshun in Guangdong, Huabei Oilfield and Gonghe in Qinghai Province, were selected to collect the environmental impact inventory for the whole life cycle of geothermal power generation system in China. The evaluation indexes of three main environmental impact potentials for six different processes of geothermal power station were analyzed: acidification potential, eutrophication potential and global warming potential. It is found that the drilling and completion process accounts for 46.28%, 45.90% and 27.52% of the acidification potential, global warming potential and eutrophication potential of geothermal power stations, respectively. The environmental impact of underground and overground systems contributes equally; the geothermal gradient has a negative correlation with the environmental impact potential of the whole life cycle of geothermal power stations.