| Summary: | This study explores the feasibility and potential techno-economic advantages of employing microwaves for direct air capture (DAC) applications. The experimental setup resembles an industrial-scale microwave system, utilizing a single-mode applicator and zeolite 13x beads arranged in a panel configuration. This configuration essentially represents a miniaturized version of a potential DAC plant based on microwaves. The results demonstrate that microwave irradiation rapidly and efficiently desorbs the CO _2 from sorbents with approximately 90% desorption achieved in 10 min—substantially shorter than conventional conduction-based methods. The desorption process occurred at a low temperature of about 50 °C, in contrast to nearly 120 °C in conventional bulk heating, due to selective heating near CO _2 binding sites. Our results support that desorption duration and temperature could be further reduced by applying more uniform heating while intensifying the selective process. Based on our research and recent literature, we propose three key techno-economic advantages of designing a DAC system with microwaves that are unattainable by the conventional approach. A reduced regeneration time could allow for a more compact system design while maintaining throughput. The selectivity of microwave absorption could drastically reduce energy demand, bringing it close to the sorbent’s thermodynamic energy limits. Furthermore, the low-temperature process could inhibit the thermal degradation of amines on the sorbents, which is unavoidable in conventional processes. Potential resonant CO _2 desorption by forming nonthermal plasma (NTP) is discussed. Our research highlights the feasibility and significance of employing advanced regeneration methods in the development of next-generation DAC systems.
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