High Efficiency Low Cost Electrochemical Ammonia Production

The Haber-Bosch process, one of the most impactful developments in human history, has provided enough fertilizer to the world that it is estimated nearly half of the nitrogen found in our bodies originated in a Haber-Bosch chemical plant. However, this technological marvel comes at a price. On U.S. farms, 29% of energy consumed (directly and indirectly) is in the form of fertilizers, and these same fertilizers are the second largest contributor to green house gas emissions. This is because the Haber-Bosch process must operate at high pressures and high temperatures to convert highly inert nitrogen gas to fertilizer. In addition, to obtain hydrogen for the reaction, fossil fuel reforming is used, resulting in a high carbon foot print. The extreme conditions and pre- and post-processing steps combined with the low equilibrium conversion makes these facilities highly capital intensive, inefficient and polluting. More sustainable and economical ammonia production methods will be required to support growing world demand for fertilizer.One alternative approach is to use electricity to drive the ammonia production reaction, decreasing the need for high pressure and heat thereby decreasing the energy demand and making the process more efficient. This electrochemically driven process is compatible with the use of renewable electricity, eliminating CO2 emissions from the production step. A natural synergy exists in using wind power for fertilizer production. In the Plains and Upper Midwest, excess wind production capacity, transmission limitations, and high regional demand for N-fertilizers combine to create excellent economic drivers for this technology. In addition, because electrolysis technology is highly scalable, further reduction of emissions will be realized through the reduced need for ammonia transport. Products could be envisioned that support a range of small to mid-sized farms, or could be designed on a larger scale to distribute ammonia locally for multiple farms.Our team proposes development of an efficient solid state electrochemical process utilizing anion exchange membrane (AEM) technology, which can be optimized for use with distributed renewable energy sources. This AEM-based technology is ideal for ammonia synthesis because the membranes are not expected to readily react with ammonia, enable low-cost materials of construction, and they allow the utilization of a wider array of low-cost catalysts. Results from our Phase I work showed that our AEM-based electrochemical technology is uniquely capable of low temperature and low pressure ammonia generation at an efficiency which will match the energy requirements of the Haber-Bosch process. The team has extensive competencies in cell design, tailoring of membrane and catalyst properties, and balance of plant design and integration, providing a strong foundation for the proposed work.