Methane is the second-most emitted greenhouse gas (GHG) globally, and it has over 25x more potency toward the GHG effect than carbon dioxide. Methane emissions in the U.S. are equally distributed across the energy, agricultural, and industrial sectors – and occur in relatively small volumes at each site, though the total volume is sizable (e.g., 145 billion cubic meters of methane coextracted with U.S. oil alone per year). To avoid its direct emission, this “waste” methane is typically flared to produce CO₂. Methane flaring sites contribute to approximately 2% of global CO₂ emissions. These sites represent an opportunity to convert a waste stream into desirable products. Methane (natural gas)-to-chemicals conversion units are not implemented today because of economies of scale. Because each site is relatively small, the construction of a traditional stream-reforming based gas-to-liquid plant is not economically viable. It is also not profitable to build pipelines to these sites to take the natural gas to other locations.

Recently, new concepts have been put forward for methanol production that are quoted as being more modular and possibly more profitable at smaller scales. Many of these concepts revolve around electrochemical and/or biochemical transformations. Proponents of electrochemical methane conversion have claimed that the technology will play a key role in eliminating these flare sites while opening up new business opportunities. Though this sounds very good, all of the research and development in this area remain on the bench scale as they have widely suffered from low current, high voltage losses and low faradaic efficiency. It should also be noted that there are very few studies in the literature that use economic analyses to understand the operational boundaries of a future electrochemical methane-to-methanol plant and to set realistic targets for its operation. Hence, research work is proceeding without clear operating targets in mind.

In this presentation, we will present an economic analysis on an electrochemically driven methane-to-methanol plant. We investigate a wide range of possible production rates (from 2-2000 metric tons per day), operating current densities (10-1000 mA/cm²), operating voltages (V_thermo-2.0 V) and faradaic efficiencies. This analysis also takes into consideration the cost of the electrolyzer stacks, the balance-of-plant, building sizes/layouts, labor force, etc. Over this wide design space, we determine the possible operating space that will allow for profitable operation. While doing so, we test whether electrochemical processes can economically out-compete steam reforming plants at any scale. We also identify the operating modes where electrochemical processes emit fewer greenhouse gases that traditional plants.