The journal Advanced Materials recently published an article that reviews electrochemical ammonia technologies for both synthesis and power generation. In addition to presenting a range of technologies under development, the authors, based at the University of Delaware, present "perspectives in the technical challenges and possible remedies."
On July 13, Science magazine, the flagship publication of the American Association for the Advancement of Science (AAAS), published a 2,800-word “feature article" on ammonia energy. The article, headlined, “Liquid sunshine: Ammonia made from sun, air, and water could turn Australia into a renewable energy superpower,” is uniformly open-minded and upbeat. Its opening section ends with a quote from Monash University Professor of Physics and Chemistry Doug MacFarlane; “’Liquid ammonia is liquid energy,’ he says. ‘It's the sustainable technology we need.’”
MacFarlane helped launch the Australian chapter of the NH3 Fuel Association.
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.
Last week, in Part 1 of this series on electrochemical ammonia synthesis technologies, I quoted a recent article by researchers at MIT that identified avenues for future research and development. One option was a biomimicry approach, learning from "enzymatic catalysts, such as nitrogenases," which can "either be incorporated into or provide inspiration for the design of electrocatalytic processes."
The nitrogenase enzyme, nature's ammonia synthesis technology, was developed in an iterative innovation process, otherwise known as evolution, that took hundreds of millions of years to reach this level of efficiency. According to one group of electrochemists, who presented their results at the recent NH3 Energy+ conference, nitrogenase produces ammonia in nature with an enviable 75% process efficiency - so it's no surprise that they are basing their industrial technology on it.
Last month's NH3 Energy+ conference featured presentations on a great range of novel ammonia synthesis technologies, including improvements to Haber-Bosch, and plasmas, membranes, and redox cycles. But, in a mark of a conference approaching maturity, members of the audience had at least as much to contribute as the presenters.
This was the case for electrochemical synthesis technologies: while the presentations included updates from an influential industry-academia-government collaboration, led by Nel Hydrogen's US subsidiary, the audience members represented, among others, the new electrochemical ammonia synthesis research lab at Massachusetts Institute of Technology (MIT), and a team from Monash University in Australia. The very next week, Monash published its latest results, reporting an electrochemical process that synthesized ammonia with 60% faradaic efficiency, an unprecedented rate of current conversion at ambient pressure and temperature.
During our NH3 Energy+ Topical Conference, hosted within AIChE's Annual Meeting earlier this month, an entire day of presentations was devoted to new technologies to make industrial ammonia production more sustainable.
One speaker perfectly articulated the broad investment drivers, technology trends, and recent R&D achievements in this area: the US Department of Energy's ARPA-E Program Director, Grigorii Soloveichik, who posed this question regarding the future of ammonia production: "Improvement of Haber-Bosch Process or Electrochemical Synthesis?"
New research coming out of Stanford University suggests a fascinating new direction for electrochemical ammonia synthesis technology development.
The US-Danish team of scientists at SUNCAT, tasked with finding new catalysts for electrochemical ammonia production, saw that 'selectivity' posed a tremendous challenge - in other words, most of the energy used by renewable ammonia production systems went into making hydrogen instead of making ammonia.
The new SUNCAT solution does not overcome this selectivity challenge. It doesn't even try. Instead, these researchers have avoided the problem completely.
One of the many encouraging announcements at the recent Power-to-Ammonia conference in Rotterdam was the news that the Korea Institute of Energy Research (KIER) has extended funding for its electrochemical ammonia synthesis research program by another three years, pushing the project forward through 2019.
KIER's research target for 2019 is significant: to demonstrate an ammonia production rate of 1x10-7 mol/s·cm2.
If the KIER team can hit this target, not only would it be ten thousand times better than their 2012 results but, according to the numbers I'll provide below, it would be the closest an electrochemical ammonia synthesis technology has come to being commercially competitive.
Yet another national laboratory is developing technology for renewable ammonia, this time in Germany at the DLR, the German Aerospace Center.
At the Institute of Thermodynamic Engineering, the DLR is developing a method for electrochemical ammonia synthesis at ambient conditions.