Moisture Swing Direct Air Capture for Carbon Dioxide Enrichment in Closed Greenhouse Environments

Master thesis (2024)

Authors

J.J.P. Vianen Mechanical Engineering

Contributors

Tim M.J. Nijssen Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering (mentor)
T.J.H. Vlugt Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering (graduation committee member)
T. Keviczky Team Tamas Keviczky - Mechanical, Maritime and Materials Engineering (graduation committee member)
Faculty
Mechanical Engineering
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Published Date

25-06-2024

Language

English

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Faculty

Mechanical Engineering

Abstract

While CO2 is one of the factors increasing the global temperature, it is also utilized in the agriculture to enhance crop yield. In the agriculture, a sustainable solution to CO2 mitigation would potentially lie in the greenhouses. A moisture swing direct air capture system can adsorb CO2 from the air through changes in humidity levels between the adsorption and the desorption stages. During adsorption dry air is required, while during desorption humid air is required. In a greenhouse, where humid air is typically required for the crops and CO2 enhancement is often achieved through fossil-fuel combustion, a moisture swing system could be a sustainable innovation.

Insights into the feasibility and potential implementation of a moisture swing column designed to enhance CO2 concentrations within a greenhouse are obtained through an investigation of the key parameters of the sorbent, the effect of global climate conditions on the sorbent, a parameter sensitivity analysis of the performance of the system, and a preliminary techno-economic viability assessment.

A one-dimensional numerical model was developed to solve the mass balance of a cylindrical adsorption column. Critical key parameters that affect the CO2 saturation coverage of the sorbent are the gas phase CO2 concentration, the relative humidity, and the temperature. Investigated is how these conditions vary globally, highlighting optimal arid climate regions with a high saturation coverage. It was found that seasonal and diurnal deviations are significantly higher in regions where a lower saturation coverage can be reached. From the sensitivity analysis of the parameters and conditions, it was that a 1.6-meter-long column achieved a system efficiency of 15.0 micromoles of CO2 per kilogram sorbent per second, a water loss of 45.4 moles of water per mole of CO2, and a system productivity of 9.05 moles of CO2 per second. In the short term, the majority of costs are attributed to the capital expenditures, whereas in the long term, operational expenditures become the dominant expense.