Enriching and controlling the CO2 concentration level in indoor farming through electroactive 13X-filled biocarbon tubular elements

Abstract

Electrothermal biocarbon tubes filled up with zeolite 13X were studied as hybrid adsorbents for the CO2 enrichment of greenhouse’s environment through electric swing adsorption (ESA) cycles. These adsorbents captured CO2 from dilute CO2 gas streams with CO2 mole fractions as low as 1.0%. The direct heating of the adsorbent was achieved through the Joule effect by applying electric potential between the tube ends. Due to the rapid increase of the temperature, a CO2 enriched gas phase was released for the supply of CO2 in indoor grow rooms. A conceptual design of the ESA cycle was elaborated by using the equilibrium adsorption isobar curves estimated for these low CO2 levels. The presence of ambient air did not affect the carbonaceous material’s structure at high temperature. However, the CO2 enrichment was reduced by near 30%. The tube-shaped hybrid material demonstrated stability and repeatability for an effective CO2 supplementation in indoor agriculture.