This series of articles on the future of ammonia synthesis began with a report on the NH3 Energy+ conference presentation by Grigorii Soloveichik, Program Director at the US Department of Energy's ARPA-E, who categorized the technologies as being either improvements on Haber-Bosch or electrochemical (with exceptions).
ARPA-E invests in "transformational, high-risk, early-stage research," and recently began funding ammonia synthesis technologies, not to make renewable fertilizer but to produce "energy-dense zero-carbon liquid fuel." This article will introduce the six electrochemical technologies currently in development with funding from ARPA-E.
At the recent NH3 Energy+ Topical Conference, Grigorii Soloveichik described the future of ammonia synthesis technologies as a two-way choice: Improvement of Haber-Bosch or Electrochemical Synthesis.
Two such Haber-Bosch improvement projects, which received ARPA-E-funding under Soloveichik's program direction, also presented papers at the conference. They each take different approaches to the same problem: how to adapt the high-pressure, high-temperature, constant-state Haber-Bosch process to small-scale, intermittent renewable power inputs. One uses adsorption, the other uses absorption, but both remove ammonia from the synthesis loop, avoiding one of Haber-Bosch's major limiting factors: separation of the product ammonia.
Sustainable ammonia can be produced today: doing so would use electrolyzers to make hydrogen to feed the traditional Haber-Bosch process. In a very few years, new technologies will skip this hydrogen production phase altogether and make ammonia directly from renewable power in an electrochemical cell. Further down the pipeline, next generation technologies will mimic nature, specifically the nitrogenase enzyme, which produces ammonia naturally.
One of these next generation technologies is currently producing impressive results at the US Department of Energy's (DOE) National Renewable Energy Laboratory (NREL).