(591g) Portable Process Development for Methanol Synthesis from Stranded Methane

In 2020, flared and vented natural gas (NG), derived from the petroleum industry, represented an emission level of 6.1 million metric tons CO₂ equivalent (CO₂e) in the US [1]. These associated gases are produced at oil producing wellheads that are often located in remote sites, with gas outputs that vary over their lifespans of several years, rendering the investments in pipeline infrastructure unattractive for transporting this stranded natural gas to end users. Instead, these gases are disposed, with flaring as the most common approach, to reduce methane emissions via combustion to form CO₂, which is 84 times less potent greenhouse gas over a 20-year horizon. The inherent efficiencies (~92%, [2]) of these flaring units, however, still lead to significant methane release. One alternative and revenue-generating pathway for these sources of stranded methane is through conversion to energy-dense, readily transportable methanol, which could be implemented economically if the volume and time scales of such processes can be matched to the size and lifespan of individual oil wells with associated gas.

M2X Energy Inc. has developed a prototype of a modular and portable system, which incorporates an air-breathing partial oxidation (POX) engine reformer and a methanol synthesis unit, capable of processing 75,000 standard cubic foot per day (scfd) NG to produce roughly 500 gallons/day methanol [3]. While employing similar process steps as in conventional methanol synthesis plants, the M2X system favors system simplicity and robustness over optimized yield, leading to technical tradeoffs that leverage the use of standardized process equipment more suitable for mass-production. In this work, we mention the design choices for these distributed systems and compare them to the process steps more commonly seen in conventional methanol plants. We emphasize how our design basis and process modeling were guided and enhanced by extensive bench-scale experimentation, attained through the close collaborations with our university partners at the University of Central Florida (Florida Solar Energy Center), and share our collective learnings on the unique considerations inherent within these small, modular processes intended for harvesting stranded methane.

References

1. EPA (2022) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020. U.S. Environmental Protection Agency, EPA 430-R-22-003.
2. Schulz, R. and de Oliviera Bredariol, T., “Flaring Emissions,” IEA, Paris, 2022
3. Yelvington, P. E.; Browne, J. B.; Yik, E.; Merical, K. I.; Dean, A. J.; Randolph, A. On Piston Engines as Hydrocarbon Gas Reformers for Modular, Distributed Chemical Production, JAECS, 13, 2023, 100117