Chemical and Biomolecular Engineering
Dean of Engineering
Dr. Ed Cussler
University of Minnesota
Distributed Ammonia Synthesis
Thursday, September 7, 2017
to 3:30 PM
210 Herzstein Hall
6100 Main St
Houston, Texas, USA
We are developing a small-scale ammonia synthesis plant powered by wind energy. This is a major departure, because ammonia is currently made with energy from fossil fuels, especially natural gas. In contrast, the wind energy used here is sustainable but stranded, far from urban population centers but near locations of ammonia fertilizer demand. The wind energy is converted to electricity used for pressure swing absorption of air to make nitrogen, and for electrolysis of water to make hydrogen. Nitrogen and hydrogen are combined in a small-scale Haber process to synthesize ammonia. However, because of the plant’s small size and large capital, the ammonia made costs about twice as much as that made from fossil fuels.
To reduce this capital, we are making the ammonia with a conventional catalyst but an absorption using ammines. The rate limiting step can now be not the chemical kinetics or ammonia condensation, but the speed of the pump recycling the unreacted gases. The absorbents, which originally had a capacity of one percent stoichiometric and a regeneration time of six hours, now have a capacity of over 90% stoichiometric and a regeneration time of five minutes. Because the operating pressure drops from 130 to 10 bar, the capital required for the process is reduced.
Our studies explore the feasibility of this small process to harvest stranded energy. The ammonia produced can either be used in rural areas as a fertilizer or in urban areas as a hydrogen carrier for fuel cells. Whether it is successful in practice is not yet known.
Biography of Dr. Ed Cussler:
Ed Cussler, Distinguished Institute Professor at the University of Minnesota, was educated at Yale (BE, 1961) and Wisconsin (PhD, 1965). After thirteen years at Carnegie-Mellon University, Cussler joined the University of Minnesota in 1980. He has written over 250 articles and five books, including Diffusion, Bioseparations, and more recently, Chemical Product Design. Cussler, who served the American Institute of Chemical Engineers (AIChE) as President, was awarded the Colburn (1975) and Lewis (2001) awards, and was the Institute Lecturer (2014). He holds honorary doctorate degrees from the Universities of Lund (2002) and Nancy (2007). Cussler is a Fellow of the American Association for the Advancement of Science and a member of the National Academy of Engineering. His current research interest is the production of ammonia from stranded wind energy, that is, “putting wind energy in a bottle.”