Techno-economic analysis of electrochemical carbon capture from oceanwater integrated with hydrates-based sequestration

Abstract

Carbon capture and sequestration (CCS) will play a crucial role in reducing the negative effects of climate change, with a projected 10 GtCO₂/yr capacity needed by 2050. Along with scientific research, comprehensive techno-economic analyses (TEA) are needed to analyze the economic attractiveness of various CCS concepts being proposed. Presently, a TEA was conducted for a novel CCS concept which integrates indirect ocean capture (IOC) with carbon dioxide (CO₂) hydrates-based sequestration (HBS) using existing offshore platforms. Crucially, there is no CO₂ transportation involved due to onsite seabed sequestration. Furthermore, water pumping distances are significantly reduced (in comparison to coastal IOC plants), which reduces the costs noticeably. The proposed concept does not require desalination, which further improves prospects for implementation. For a 25-yr, 1 MtCO₂/yr project, the total levelized cost for capture and sequestration is 1130 $/tCO₂; CO₂ capture accounts for 97 % of the cost (with water pretreatment dominating costs). Contributions of various processes to the total cost are quantified and a sensitivity analysis conducted to identify avenues for cost reduction. A combined best case of parameters reduces the cost to 887 $/tCO₂ and 25 $/tCO₂ for capture and sequestration, respectively. Preliminary thermodynamics-based analysis in the Gulf of Mexico identifies more than 75 existing offshore platforms which can host such CCS projects.