Process design and cost analysis of onboard carbon capture system with novel thermal energy generation method and capture process modification

Abstract

This study proposed a new thermal energy generation method and an enhanced carbon capture process by applying capture process modifications for reducing the energy consumption of onboard CO2 capture systems (OCCS). Firstly, an economical approach for thermal energy generation, utilizing heat pumps and waste heat from engine cooling water, was proposed. Secondly, low-energy demand capture processes for ships with capture process modifications were investigated. Focusing on ship engines with EGR characterized by high recirculation rates, increased CO2 concentrations, and decreased exhaust gas flows, this study applied modifications to the carbon capture process, such as absorber inter-cooling, rich amine split, and lean vapor compression, with the aim of measuring the energy consumption and additional CO2 emissions associated with the capture process. Thirdly, the new thermal energy generation method and capture process enhancements were combined within onboard CO2 capture systems for large vessels (Oil tanker). The study investigated the subsequent energy consumption and life cycle costs arising from escalating ship emission regulations. Furthermore, a study was conducted to assess the implications of implementing a carbon tax (GHG levy) on ship fuels, as it is one of the candidates for the IMO's mid-term measures to reduce greenhouse gas emissions in the maritime sector. As a result, an economical onboard carbon capture system with a life-cycle cost of less than 150 USD per ton of CO2 was proposed, and furthermore, the potential to significantly reduce ship carbon emissions to near-zero levels (with a capture rate of 97.9%) through the use of OCCS was proposed and investigated.