Conversion of CO2 in a gas mixture into some chemical products typically require three-step procedures: capture, release, and conversion. To reduce process energy requirement, we apply a streamlined concept (Combined Carbon Capture and Conversion, quad-C), in which the process system is intensified by making 1) the reactant concurrently serve as absorbent, or making 2) the catalyst concurrently serve as adsorbent. The captured CO2 attached to another player of reaction is subsequently subject to the catalytic conversion process, skipping the CO2 release procedure. In this project, we aim to establish an effective direct air capture (DAC) system applying the quad-C concept, by developing modules using CO2 permselective membrane, and Layered Double Oxide / Hydroxide switching columns. In addition to the quad-C concept, we explore modularized process system structures, that allow economically acceptable system design with excellent carbon budgets, depending on the variations in feed gas quality and available energy sources at the target sites. The systemwide performance will be monitored in the course of development, and ensured to be feasible and effective at the end of the project, using Techno-Economic and Life Cycle Assessments.