Industrial Ecology Programme and Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU) , 7491 Trondheim, Norway.
Environ Sci Technol. 2013 Sep 3;47(17):9604-11. doi: 10.1021/es401820p. Epub 2013 Aug 23.
The ability of hydropower to contribute to climate change mitigation is sometimes questioned, citing emissions of methane and carbon dioxide resulting from the degradation of biogenic carbon in hydropower reservoirs. These emissions are, however, not always addressed in life cycle assessment, leading to a bias in technology comparisons, and often misunderstood. The objective of this paper is to review and analyze the generation of greenhouse gas emissions from reservoirs for the purpose of technology assessment, relating established emission measurements to power generation. A literature review, data collection, and statistical analysis of methane and CO2 emissions are conducted. In a sample of 82 measurements, methane emissions per kWh hydropower generated are log-normally distributed, ranging from micrograms to 10s of kg. A multivariate regression analysis shows that the reservoir area per kWh electricity is the most important explanatory variable. Methane emissions flux per reservoir area are correlated with the natural net primary production of the area, the age of the power plant, and the inclusion of bubbling emissions in the measurement. Even together, these factors fail to explain most of the variation in the methane flux. The global average emissions from hydropower are estimated to be 85 gCO2/kWh and 3 gCH4/kWh, with a multiplicative uncertainty factor of 2. GHG emissions from hydropower can be largely avoided by ceasing to build hydropower plants with high land use per unit of electricity generated.
水力发电在减少气候变化方面的作用有时会受到质疑，原因是水力发电水库中生物成因碳的降解会排放甲烷和二氧化碳。然而，这些排放物在生命周期评估中并不总是被考虑到，导致技术比较存在偏差，而且往往被误解。本文的目的是审查和分析水库温室气体排放的产生，以便进行技术评估，将已建立的排放测量与发电联系起来。对甲烷和 CO2 排放进行了文献综述、数据收集和统计分析。在 82 项测量的样本中，每千瓦时水力发电产生的甲烷排放量呈对数正态分布，范围从微克到数十公斤。多元回归分析表明，每千瓦时电量的水库面积是最重要的解释变量。每水库面积的甲烷排放通量与该地区的自然净初级生产力、发电厂的年龄以及测量中是否包括冒泡排放物有关。即使这些因素一起，也无法解释甲烷通量的大部分变化。估计全球水力发电的温室气体排放量为 85gCO2/kWh 和 3gCH4/kWh，乘数不确定性系数为 2。通过停止建造每单位发电量土地利用面积高的水电站，可以在很大程度上避免水力发电的温室气体排放。
