Lowering the Bar to Methanol Production
Methanol is a key chemical ingredient for the production of liquid fuels, solvents, resins and polymers. A common method for producing the compound, steam methane reforming (SMR), entails applying high-temperature (approximately 800 to 1,000 degrees Celsius [1,472 to 1,832 degrees Fahrenheit]) steam to natural gas or another methane-rich feedstock to produce "syngas." Next, impurities are removed from the syngas and a catalyst is applied to yield liquid methanol.
SMR is not without its drawbacks, however, according to a Connecticut-based manufacturer of stationary fuel cell power plants.
"Steam reforming to generate methanol is highly energy-intensive, with a substantial carbon footprint," noted Kurt Goddard, vice president of investor relations with FuelCell Energy, Inc. (FCE). It "generates criteria pollutants such as smog-producing nitrogen oxides (NOx) and particulate matter that can cause public health issues."
SMR's complexity, which stems from its reliance on high temperatures through multiple steps, limits its practical application to large plants that can achieve a commercially viable economy of scale, added Ted Aulich, principal process chemist for fuels and chemicals with the University of North Dakota Energy and Environmental Research Center (EERC).
Aulich and his team at EERC recently embarked on a three-year project led by FCE to develop a simpler, less cost-prohibitive alternative to the two-step SMR process. Their goal is to develop a fuel cell capable of converting natural gas and other methane-rich gas into methanol.
"This project involves new technologies that produce value-added products from both fossil and renewable methane," Tom Erickson, EERC chief executive officer, stated in an August press release announcing the endeavor.
"Generating methanol from fuel cells addresses the environmental issues surrounding methanol production as fuel cells are virtually absent of pollutants and have a low carbon footprint reflecting the highly efficient energy conversion process," said Goddard.
The battery-like electrochemical gas-to-liquid (EC-GTL) technology concept could result in a modular, efficient and cost-effective methanol production device, according to Aulich. He explained the fuel cell that FCE is developing would be scalable for a wide variety of deployments – from producing methanol at a large industrial plant to installing a single unit on an oil well to monetize associated gas that would otherwise be flared off.
In September 2011, 36 percent of the natural gas produced in North Dakota's Bakken formation was flared off, according to the state's Department of Mineral Resources.
Thanks to the addition of new gas gathering infrastructure as well as new state policies requiring oil and gas producers to capture more associated natural gas at well sites, the percentage of gas flared statewide has fallen to 20 percent as of Oct. 13, 2015. By the fourth quarter of 2020, North Dakota wants producers to capture 91 percent of associated gas.
EC-GTL could help solve a regulatory emissions problem for oil producers with a solution that generates revenue, according to FCE's Kurt Goddard.
"A market for this disruptive technology is enhanced oil recovery in remote locations where natural gas is flared as it is not economical to transport the gas," he said. "Using flare gas as the fuel source eliminates the emission of NOx from the flaring process and utilizes a fuel source that would otherwise be wasted."
"As envisioned, the one-step EC-GTL process works at a temperature of about 400 to 600 degrees Celsius (752 to 1,112 degrees Fahrenheit) and ambient pressure to partially oxidize methane to methanol," Aulich said.
Through the course of the $3.5 million project, which received funding from the U.S. Department of Energy's Advanced Research Projects Agency (ARPA-E) and the North Dakota Department of Commerce, EERC will work to improve the performance and economics of an "anode catalyst," which Aulich explained is a critical component of EC-GTL.
Aulich recently elaborated on the research team's plans for the EC-GTL concept in an interview with DownstreamToday. Read on for his insights.
DownstreamToday: What are the shortcomings of existing anode catalyst technology that you intend to correct?
Ted Aulich: Key shortcomings are low natural gas conversion and low selectivity for methanol production, due to the difficulty in providing precisely the right amount of catalytic activity to effect partial oxidation of methane to methanol. Too little activity will translate to insufficient oxidative power and insufficient methane oxidation to methanol. Too much activity will translate to excessive oxidative power, resulting in methane oxidation that progresses beyond methanol to yield more highly oxidized, less valuable products like carbon dioxide.
DownstreamToday: What are the respective roles of EERC and FCE in this collaboration?
Aulich: EERC is preliminarily evaluating candidate catalyst formulations. FCE will incorporate useful EERC findings along with other partner findings in design and fabrication of a complete electrochemical cell-based reactor system including anode, cathode, electrolyte and gas feed, product recovery, and unreacted methane recycle systems.
DownstreamToday: Various companies are developing plants to produce fuels and chemical building blocks from methanol. How does your work differ from what others are doing, and what niche do you see your technology filling?
Aulich: The primary difference is in the use of the electrochemical versus SMR approach to achieve a simpler technology that will enable commercial viability at smaller-scale than achievable with SMR. A key FCE target is a technology small and simple enough to deploy at individual gas wells and groups of wells.
DownstreamToday: What do you consider "smaller-scale"?
Aulich: Smallest scale will enable accommodation of produced gas from an individual oil well – a flow rate as low as 300,000 cubic feet per day.
DownstreamToday: What do you consider the most exciting potential technologies that could emerge from EERC and FCE's partnership?
Aulich: GTL technologies that are sufficiently simple – to ship, set up and operate – to enable their commercially viable deployment wherever a gas supply is available.
DownstreamToday: What do you foresee as the conventional means of supplying natural gas to your electrochemical cell?
DownstreamToday: How might EC-GTL be adapted to run on landfill gas or flare gas?
Aulich: There would be some clean-up required to ensure against introducing any catalyst-killing contaminants, such as sulfur compounds, into the electrochemical cell. Removing sulfur from gas feeds to very low levels is a well-established process used on existing FCE power plants.
DownstreamToday: Are you strictly looking at developing GTL technology that can monetize natural gas on a smaller scale?
Aulich: No. Once technology is optimized, commercialized and packaged in units of modular electrochemical cells of varying methane throughput and methanol production capacity, the cells will be "stackable" like individual fuel cells, which will enable achieving larger overall plant sizes as needed.
DownstreamToday: What do you consider the primary benefits of using modular units for EC-GTL?
Aulich: Since it is driven by the chemical energy of oxidation, EC-GTL is anticipated to require minimal energy input and may yield added value in the form of electricity and high-grade heat by-products. The size and self-contained nature of each modular EC-GTL unit will enable transport of units as needed to accommodate evolving gas-processing needs. This transportability would be advantageous in EC-GTL application to associated gas produced at North Dakota and other oil wells, where gas yields typically decline from an initial maximum at the onset of oil production to roughly 30 percent of initial maximum after about 18 months of production.
DownstreamToday: What impact do you believe EC-GTL could have on the broader methanol market?
Aulich: In addition to smaller-scale distributed applications, EC-GTL has the potential for extreme disruption of the methanol market via its application to large-scale methanol production. EC-GTL advantages versus traditional large-scale (25,000 barrels per day) SMR-based methanol plants include higher carbon efficiency, the possibility of an electricity by-product and a high-purity carbon dioxide waste stream that can be recovered at low cost for use in enhanced oil recovery and other applications. Also, while turn-down of an SMR-based methanol plant results in a significant efficiency penalty, the modularity of an EC-GTL plant would enable sub-capacity operation without sacrificing efficiency. In addition to methanol producers, large EC-GTL plant customers would include oil and gas refiners interested in methanol as an intermediate in production of gasoline and/or chemicals, use of methanol in gas processing and/or hydraulic fracturing operations, and use of carbon dioxide in enhanced oil recovery, all of which could have significant relevance to improving the efficiency and competitiveness of North Dakota (and other state) oil and gas production and in-state value-added processing.
Matthew V. Veazey has written about the oil and gas industry since 2000. Email Matthew at firstname.lastname@example.org. Twitter: @The_Mattalyst