(20a) Direct Air Capture with Membranes for Crop Carbon Enrichment

Membranes are utilized to perform direct air capture (DAC) by extracting and mildly concentrating the CO2 in air from 400 ppm to over 1200 ppm (a factor of 3 or more increase), and sending this concentrate into low pressure ducting destined for a greenhouse. When atmosphere inside the greenhouse is increased to between 600 and 1200 ppm CO2, a practice known as crop carbon enrichment, the biomass and yield of the crop correspondingly increases. Cotton with crop carbon enrichment, for example, increases in yield by up to 100%, and the water utilization savings can be over 25%. This technology is ideally suited to replace other green house carbon enrichment CO2 sources such as a fit for purpose flue gas generator producing 5% (50,000 ppm) CO2 with natural gas, or a tank truck delivered pressure vessel supplied source costing between $100 and 200 per ton. Another membrane DAC scheme uses a large bank/ array of membranes for possible open air crop carbon enrichment applications.