Data underlying the MSc. thesis: Life Cycle Assessment of Offshore Low Head Pumped Hydro Storage

Aiming to comply with the Paris Agreement, the reduction of Europe’s GHG emissions in the energy sector is a must. Due to the intermittency of renewable sources, energy storage technologies are essential to this plan. Offshore Low Head Pumped Hydro Storage (LH PHS) is presented as an alternative to partly solve this problem. Considering that its infrastructure entails a reservoir of a 5km diameter ring in the middle of the sea and needs millions of tonnes of concrete, sand, granite and steel among other materials for its construction; environmental concerns arouse, which this report aims to address.<br>Information from the Alpheus project about the engineering requirements for an offshore LH PHS plant is used, following ISO 14044 Life Cycle Assessment (LCA) methodology. In this study, the construction, maintenance and operation of an offshore LH PHS plant are assessed, focusing on Global Warming Potential (GWP), Water Use Depletion Potential (WUDP) and Abiotic Depletion Potential for Elements (ADP-E). This is studied with and without the input of electricity, sourcing it from wind or from the Dutch grid mix. Moreover, these results are compared with Lithium iron phosphate (LFP) Batteries and for Wind-Green Hydrogen.<br>For the construction, operation and maintenance of the LH PHS plant, it is estimated that the emissions would reach 2.8Mt of CO2-eq, 601 million m3 of water and 140.2t of Sb-eq. These emissions are mainly shared between civil and electromechanical infrastructure, the former has more relevance for GWP with almost 56% of the emissions whereas the latter reaches 69% for WUDP and 98% for ADP-E. When electricity is incorporated into the equation and these emissions are translated per kWh, emissions from the generation of electricity exceed 2.4, 5.6 and 1.8 times those emissions from the infrastructure for GWP, WUDP and ADP-E. When comparing LH PHS with other technologies using wind as the only source of electricity production, LFP Batteries outperform LH PHS most of the time for GWP and WUDP, whereas LFP are consistently the worst performer for ADP-E. LH PHS always performs better than Green Hydrogen in all three impact categories.<br>If emissions reductions are to be achieved in the LH PHS case, the focus should be put on the electricity side: improving the efficiency of the plant, storing only clean energy and improving the performance of renewables. Finally, there are other considerations to LH PHS implementation that should be taken into account that are not assessed in this report. The use of materials and their circularity must be considered, as well as the social ramifications of projects like PHS and mining materials for Li-ion Batteries. Furthermore, impacts on biodiversity must be addressed and its damages should not only be minimized but restored or even improved.

为履行《巴黎协定》，欧洲必须削减能源领域的温室气体（Greenhouse Gas, GHG）排放。鉴于可再生能源的间歇性特质，储能技术对该减排计划而言至关重要。海上低水头抽水蓄能电站（Offshore Low Head Pumped Hydro Storage, LH PHS）被提出作为部分解决该问题的备选方案。考虑到该电站的基础设施需在海中修建直径5公里的环形水库，且建设过程需消耗数百万吨混凝土、砂石、花岗岩、钢材及其他多种材料，由此引发了诸多环境担忧，本报告旨在针对这些问题展开研究。

本研究采用阿尔菲厄斯项目（Alpheus project）中关于海上LH PHS电站的工程需求数据，并遵循ISO 14044生命周期评估（Life Cycle Assessment, LCA）方法学。本次评估覆盖海上LH PHS电站的建设、运维与全周期运行环节，重点关注全球变暖潜势（Global Warming Potential, GWP）、水资源消耗潜势（Water Use Depletion Potential, WUDP）以及元素非生物消耗潜势（Abiotic Depletion Potential for Elements, ADP-E）三类影响指标。研究分别设置供电与不供电两种场景，供电来源涵盖风电或荷兰电网混合电力；此外，还将评估结果与磷酸铁锂（Lithium iron phosphate, LFP）电池及风电制绿氢技术进行对比。

经测算，LH PHS电站建设、运行与维护阶段的排放可达2.8百万吨二氧化碳当量（CO2-eq）、6.01亿立方米水资源消耗量以及140.2吨锑当量（Sb-eq）。上述排放主要来自土建与机电基础设施：土建基础设施对全球变暖潜势的贡献占比最高，达总排放量的近56%；而机电基础设施则分别占据水资源消耗潜势总排放的69%与元素非生物消耗潜势总排放的98%。若将电力纳入评估体系并按每千瓦时（kWh）换算排放量，则电力生产环节的排放分别为基础设施排放的2.4倍、5.6倍与1.8倍（对应全球变暖潜势、水资源消耗潜势与元素非生物消耗潜势）。当以风电作为唯一电力来源开展技术对比时，磷酸铁锂电池在全球变暖潜势与水资源消耗潜势维度上多数场景下优于LH PHS，但在元素非生物消耗潜势维度始终表现最差；而LH PHS在三类影响指标上均优于绿氢技术。

若要实现LH PHS电站的减排目标，应将工作重心置于电力环节：包括提升电站运行效率、仅存储清洁能源以及优化可再生能源发电性能。此外，LH PHS电站的落地实施还存在本报告未覆盖的其他考量因素：需重视材料使用与材料循环利用情况，同时关注抽水蓄能电站项目及锂离子电池原材料开采带来的社会影响；更需针对性应对项目对生物多样性造成的冲击，不仅要最大限度降低损害，还应开展生态修复甚至实现生态环境的改善。