Atmospheric Water Harvesting Systems for Utilization of Waste Natural Gas From Oilfields and Landfills

Excess natural gas produced in oilfields is routinely flared due to the absence of alternative uses. Similarly, landfills emit large quantities of methane, which is primarily flared or vented. Both these activities result in large scale energy waste and undesired methane and carbon dioxide emissions. This work examines the benefits of using excess natural gas to harvest atmospheric moisture. Natural gas-powered refrigeration systems can enable large scale dehumidification via condensation. The harvested water can be used for water-intensive operations like hydraulic fracturing, drilling and waterflooding in nearby oilfields. This solution thus addresses the issues of energy waste, water and greenhouse gas emissions A first-order model is used to estimate the water harvest, based on the gas flow rate, ambient weather and the refrigeration system. The benefits of flared gas-powered water harvesting are quantified for the Eagle Ford (Texas) and the Bakken (North Dakota) Shales, which account for the bulk of US flaring. The benefits of landfill gas-powered water harvesting are quantified for the Barnett (Texas), and Monterey (California) Shales, which can be served by 30 and 15 landfills, respectively. Overall, flared gas utilization for water production can meet 15% and 60% of the annual water requirements of the Eagle Ford and Bakken Shales, respectively. The water harvested using landfill gas (from nearby landfills) can meet 22% and 73% of the annual water requirements of the Barnett and Monterey Shales, respectively. This technology will also eliminate millions of trucking trips to transport water. Overall, this waste-to-value concept has global relevance, since a combination of excess gas availability, water scarcity and hot-humid conditions is common in many regions of the world.