Carbon capture and storage (CCS) is a key technology to reduce carbon dioxide (CO₂) emissions from industrial processes in a feasible, substantial, and timely manner. For geological CO₂ storage to be safe, reliable, and accepted by society, robust strategies for CO₂ leakage detection, quantification and management are crucial. The STEMM-CCS (Strategies for Environmental Monitoring of Marine Carbon Capture and Storage) project aimed to provide techniques and understanding to enable and inform cost-effective monitoring of CCS sites in the marine environment. A controlled CO₂ release experiment was carried out in the central North Sea, designed to mimic an unintended emission of CO₂ from a subsurface CO₂ storage site to the seafloor. A total of 675 kg of CO₂ were released into the shallow sediments (∼3 m below seafloor), at flow rates between 6 and 143 kg/d. A combination of novel techniques, adapted versions of existing techniques, and well-proven standard techniques were used to detect, characterise and quantify gaseous and dissolved CO₂ in the sediments and the overlying seawater. This paper provides an overview of this ambitious field experiment. We describe the preparatory work prior to the release experiment, the experimental layout and procedures, the methods tested, and summarise the main results and the lessons learnt.

碳捕集与封存（CCS）是一项关键技术，以可行，大量和及时的方式减少工业过程中的二氧化碳（CO ₂）排放。为了使地质CO ₂储存安全，可靠并为社会所接受，可靠的CO ₂泄漏检测，量化和管理策略至关重要。STEMM-CCS（海洋碳捕集与封存环境监测策略）项目旨在提供技术和理解，以实现对海洋环境中CCS场所进行成本有效的监测并为其提供依据。在北海中部进行了受控的CO ₂释放实验，旨在模拟地下CO的意外CO ₂排放₂存放地点到海底。总共675千克的CO ₂以6至143千克/天的流速释放到浅层沉积物中（海床以下约3 m）。结合使用了新技术，现有技术的改进版本以及经过充分验证的标准技术来检测，表征和量化沉积物和上覆海水中的气态和溶解态CO ₂。本文概述了这一雄心勃勃的现场实验。我们描述了发布实验之前的准备工作，实验布局和程序，测试的方法，并总结了主要结果和经验教训。