We present the design, construction, characterization, and analysis of a prototype process for a novel electrochemical platform of candidate negative emissions technologies (NETs), termed indirect ocean capture. The IOC technologies remove carbon dioxide gas from the atmosphere by leveraging both air-ocean gas exchange and the pH sensitivity of the ocean’s carbonate buffer system. The system characterized in this paper enables two configurations that capture CO₂ either as a pure gas or as a solid mineral. Both configurations use the acid and base produced by the membrane electrodialysis of ocean water. The first configuration, termed the ‘acid process’, acidifies ocean water or brine to shift the carbonate buffer system towards dissolved CO₂ gas, which is vacuum stripped from the acidified brine. The second configuration, termed the ‘base process’, adds base to the brine to shift the carbonate buffer system towards carbonate ions, which precipitates as CaCO₃. A closed loop cycle is achieved by returning this decarbonized and alkalinized brine to the ocean for additional CO₂ absorption from the air. Our evaluation of this prototype scale system focused on the parameters that have the most influence on the ultimate cost of the extracted CO₂. In a concurrent techno-economic study, the most cost-sensitive parameters were shown to be the efficiencies of the anion and cation exchange membranes, the number and orientation of CO₂ extraction membranes, and the volume of base required for CaCO₃ precipitation. The measured parameters provide target values for commercial deployment. The experiments in this study were used to inform the concurrent techno-economic study that quantifies in detail the projected cost of avoided CO₂ achievable with this process.

我们介绍了一种用于候选负排放技术（NETs）的新型电化学平台的原型工艺的设计，构造，表征和分析，该技术被称为间接海洋捕集。IOC技术通过利用海洋气体交换和海洋碳酸盐缓冲系统的pH敏感性来从大气中清除二氧化碳气体。本文所描述的系统实现了两种配置，可将CO ₂捕获为纯气体或固体矿物。两种配置都使用由海水的膜电渗析产生的酸和碱。第一种配置称为“酸处理”，可酸化海水或盐水，使碳酸盐缓冲液系统转化为溶解的CO ₂气体，将其从酸化盐水中真空汽提。第二种配置称为“碱处理”，它向盐水中添加碱，以使碳酸盐缓冲液系统向碳酸根离子迁移，并以CaCO _3的形式沉淀出来。通过将这种脱碳和碱化的盐水返回到海洋以从空气中吸收更多的CO _2，可以实现闭环循环。我们对该原型规模系统的评估集中在对提取的CO ₂的最终成本影响最大的参数上。在一项并行的技术经济研究中，对成本最敏感的参数显示为阴离子和阳离子交换膜的效率，CO ₂的数量和方向萃取膜，以及沉淀CaCO ₃所需的碱量。测得的参数为商业部署提供了目标值。这项研究中的实验被用来为同时进行的技术经济研究提供信息，该研究详细量化了此过程可实现的避免CO ₂的预计成本。