(69f) Wind-Powered Ammonia Synthesis

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.

To make this wind-based process more competitive, we are making the ammonia with a conventional catalyst but separating the ammonia by absorption using ammines. The rate limiting step can now be not the chemical kinetics or ammonia separation, but the speed of the pump recycling the unreacted gases. Because the operating pressure drops from 150 to 20 bar, the cost for the process is reduced. To further intensify the synthesis, we are testing putting both catalyst and absorbent in the same vessel.

We continue to explore the feasibility of this small process to harvest stranded energy.