Fuel cells are one of the most attractive distributed power generation technologies. They combine hydrogen and oxygen to produce electricity, with water and heat as the by-products. Since the conversion of the fuels to energy takes place directly without combustion, the process is highly efficient, clean, and quiet. However, problems associated with hydrogen sources and storage, and limitations in fuel flexibility are delaying the commercialization of fuel cells as a competitive technology for both transportation and stationary applications.
Researchers at CEER are working on the development of a new technology that can help confront all the issues mentioned above. The technology is called “Ammonia Electrolysis” and the electrochemical cell is called “Ammonia Electrolytic Cell (AEC).
The AEC operates as follows: aqueous ammonia (NH3/H2O) in the presence of potassium hydroxide (KOH) is fed into the anode compartment of the AEC where NH3 is oxidized in the presence of OH- according to
2NH3 + 6OH- -------> N2 + 6H2O + 6e-
At the cathode a solution of KOH is supplied and water is reduced in alkaline medium according to
2H2O + 2e- -------> H2 + 6OH-
Therefore the overall reaction is given by
2NH3 -------> N2 + 3H2
The theoretical voltage for the production of hydrogen at 25°C through electrolysis of ammonia in alkaline media is 0.058 V with an energy consumption of 1.55 W-h per gram of H2 produced. KOH is the electrolyte for the system and water acts as the solvent, that is, neither KOH nor water are consumables during the operation of the cell.
- Low operating temperature. Maximum temperature about 60°C.
- Could operate with proton exchange membrane (PEM) fuel cells as a power source.
- Part of the energy of the PEM fuel cell can be used to power the AEC with still net energy left.
- Potential use in residential houses due to low operating temperature.
- Easy to operate with renewal energy sources (solar and wind energy)
- Could be extended to use ammonia from waste (e.g., farmers, waste water, etc).
- Hydrogen is produced on demand.The infrastructure for ammonia distribution and storage is already available.
- F. Vitse, M. Cooper and G.G. Botte, "On the use of ammonia electrolysis for hydrogen production" J. Power Sources, 142, p18 (2005)
- M. Cooper and G. G. Botte, "Hydrogen Production from the Electro-oxidation of Ammonia Catalyzed by Platinum and Rhodium on Raney Nickel Substrate," J. Electrochem. Soc., 153, pA1894 (2006)
- E.P. Bonnin, E.J. Biddinger and G.G. Botte, "Effect of catalyst on electrolysis of ammonia effluents," J. Power Sources, 182, p284 (2008)
- B.K. Boggs and G.G. Botte, "On-board hydrogen storage and production: An application of ammonia electrolysis," J. Power Sources, 192, p573 (2009)
- G.G. Botte, F. Vitse and M. Cooper, "Electro-catalysts for the oxidation of ammonia in alkaline media." U.S. Patent No. 7485211 (Issued Feb. 3, 2009)
- M. Muthuvel and G.G. Botte, Trends in Ammonia Electrolysis, Modern Aspects of Electrochemistry, No. 45, R.E. White (ed.), p207, Springer New York (2009)
- G.G. Botte, "Electro-catalysts for the oxidation of ammonia in alkaline media." U.S. Patent No. 7803264 (Issued Sept 28, 2010)
- B.K. Boggs and G.G. Botte, "Optimization of Pt-Ir on carbon fiber paper for the electro-oxidation of ammonia in alkaline media," Electrochim. Acta, 55, p5287 (2010)
- D.A. Daramola and G.G. Botte, "Theoretical study of ammonia oxidation on platinum clusters – Adsorption of ammonia and water fragments," Comp. Theor. Chem. 989, p7 (2012)