CDR systems can be conceptually divided into two basic types: cyclical and "use-once". Cyclic CDR systems use a single material to repeatedly capture CO₂, which is regenerated and reused after CO₂ extraction, while “once-used” systems use a material that reacts with CO₂ only once and is then distributed into the environment. Cyclic systems are more energy intensive.

• Cyclic CDR systems, such as chemical direct air capture (DAC), repeatedly reuse a single batch of CO₂ capture material in a cyclic process. After a material has captured a certain amount of CO₂, the CO₂ is extracted (typically using heat), the CO₂ is separated into a relatively clean stream suitable for storage (geological sequestration or mineralization), and the material is reused in the next cycle. The main input (apart from air) for cyclic systems is energy. Cyclic systems have a minimum energy requirement given by the second law of thermodynamics. Hybrid (technical/biological) carbon capture systems, such as BECCS, where the output is essentially a clean stream of CO₂, are also essentially cyclic systems when the entire set of processes, including the initial photosynthesis by plants, is considered.
• "Once-used" CDR systems, such as accelerated rock weathering (ERW) and ocean alkalinity enhancement (OAE), use materials that are out of equilibrium with the atmosphere, such as alkaline minerals extracted from the ground or certain types of industrial by-products. After processing, this material is widely distributed and allowed to react with atmospheric CO₂ to sequester the carbon. The output of a “use-once” process is a modified version of the input material that cannot be easily reused to capture additional carbon. “Use-once” systems do not have the same minimum energy input requirements as cyclical systems. However, they still have significant energy needs (e.g., crushing and transporting the material). Because the output of these systems is not pure CO₂ and in many cases ends up widely distributed on land or in the ocean, complicated environmental and ecological issues need to be considered.
• Spring