Last week, ARPA-E announced funding for eight technologies that aim to make ammonia from renewable electricity, air, and water.
The technological pathways being developed include adaptations of the Haber-Bosch process – seeking improvements in catalysts and absorbents – as well as novel electrochemical processes.
Each of these awards must produce an “end-of-project deliverable.” For chemical processes, this will be a “bench scale reactor” that produces >1 kg of ammonia per day; and for electrochemical projects, it will be a “short stack prototype” capable of producing >100 g of ammonia per day.
These aren’t the first funds for low-carbon ammonia production to have recently come out of ARPA-E, the US Department of Energy’s Advanced Research Projects Agency – Energy. In October, I wrote in depth about the agency’s desire to develop “transformative” ammonia synthesis technologies for use in energy applications.
These latest awards are part of ARPA-E’s REFUEL program (“Renewable Energy to Fuels Through Utilization of Energy-Dense Liquids”), which aims to develop technology for the synthesis of “carbon-neutral liquid fuels.”
Carbon-neutral liquid fuels … are hydrogen-rich and made by converting molecules in the air (nitrogen or carbon dioxide) and hydrogen from water into an energy-carrying liquid using renewable power.
US Department of Energy, ARPA-E’s REFUEL program
A few of these awards went to projects that will adapt the Haber-Bosch process to suit the intermittency and small-scale of renewable power generation from wind and solar.
University of Minnesota Twin Cities intends to develop “Small Scale Ammonia Synthesis Using Stranded Wind Energy.” This project will “insert an inorganic absorbent material in the ammonia synthesis loop of a traditional Haber-Bosch process,” which will “allow increased single-pass conversion and increase production rates.” Crucially, the team hopes that “this approach will allow for ammonia production at 10 times lower pressure than the Haber-Bosch process,” and therefore allow them to reduce the size of the ammonia plant without losing the efficiencies of scale.
This is the latest in the University of Minnesota’s “globally significant collection of research efforts” into sustainable ammonia production and use, benefitting from 15 years of research into renewable ammonia, bolstered by operational data gleaned from its wind-to-ammonia pilot plant, which has operated successfully since it was commissioned in 2013.
RTI International also aims to improve the Haber-Bosch process, with its “Innovative Renewable Energy-Based Catalytic Ammonia Production.” RTI International‘s innovation uses “a breakthrough catalyst … to enable operation at temperatures at least 20 percent lower, and with reduced pressures.” The benefit of this “economically viable” small-scale reactor is that, unlike regular Haber-Bosch, which requires a constant supply of power, the ammonia synthesis process “can start and stop in synchronization with intermittent renewable power sources.”
West Virginia University Research Corporation is also developing a chemical process, although less closely related to Haber-Bosch. Its project, “Renewable Energy to Fuels Through Plasma Catalytic Synthesis of Ammonia,” aims to “produce ammonia from hydrogen and nitrogen using a microwave plasma … using low temperatures and pressure … at five times the conversion rate of the Haber-Bosch process.” Because of the shorter warm-up time required, these low temperatures and pressures make the process “amenable to intermittent renewable energy sources.”
Most of the projects receiving awards under ARPA-E’s REFUEL program, however, involve electrochemical processes: a complete departure from Haber-Bosch. The majority of these focus on anion or hydroxide exchange membrane (HEM) technologies, and seek improvements over previous generations of electrochemical ammonia technologies.
Wichita State University is developing “Alkaline Membrane-Based Ammonia Electrosynthesis with High Efficiency for Renewable and Scalable Liquid Fuel Production.” The researchers at WSU aim to use a HEM cell to “increase the selectivity for ammonia product – making it more efficient – while the device’s tolerance for high electrical current would help lower costs relative to other electrochemical approaches.”
Giner, Inc‘s project, “High-Efficiency Ammonia Production from Water and Nitrogen,” also relies on HEM technology, even though Giner established its reputation in fuel cells and hydrogen production using PEM (proton exchange membrane) technology. By incorporating the HEM system and “a variety of novel catalyst materials” with its water electrolysis platform, it hopes to “reduce ammonia production capital and operating costs by 30-40 percent compared to the conventional Haber-Bosch process.”
Molecule Works, Inc is also developing a “Novel Electrochemical Membrane Reactor for Synthesis of Ammonia from Air and Water at Low Temperature and Low Pressure.” This will be a modular system, operating at low temperatures “between 50 and 180 °C.” Molecule Works proposes to “build an anion exchange membrane (AEM) using a thin porous ceramic/metal sheet … [to] provide a large catalytic reaction area per unit volume and greatly increase the diffusion rate of nitrogen gas within the cell.”
Storagenergy Technologies, Inc is working on “High Rate Ammonia Synthesis by Intermediate Temperature Solid-State Alkaline Electrolyzer.” Storagenergy Technologies is a new company that licenses technology from universities, and its “innovation relies on a cell containing an electrolyte made from a solid composite and nanostructured catalysts … capable of producing ammonia at temperatures between 100 and 300 °C without the need for separate hydrogen production, thus decreasing feedstock costs.”
Finally, FuelCell Energy, Inc is working on “Protonic Ceramics for Energy Storage and Electricity Generation with Ammonia.” This “innovation relies on an electrode
incorporating a ruthenium catalyst – a material that reduces the energy requirement of the reaction – that has shown to be more active for ammonia production than traditional methods.” Although Ruthenium is a rare metal, it is very good for ammonia production, being “10-20 times more active than traditional magnetite catalyst,” according to Halliburton’s old marketing materials for its KBR Advanced Ammonia Process (KAAP). FuelCell Energy hopes to “increase ammonia production rates to 100 times current electrochemical methods—comparable with commercial processes while avoiding the need for separate hydrogen production.”
Notably, FuelCell Energy is the only project receiving funding under the REFUEL program that meets both Category 1 and Category 2 criteria. Category 1 is for synthesis projects, while Category 2 is for fuel-use projects: FuelCell Energy’s project will be “a reversible electrochemical cell,” that can both “produce ammonia from nitrogen and water or consume ammonia to generate electricity.”
ARPA-E’s REFUEL program awarded funding to a total of 16 projects for carbon-neutral liquid fuels. Of these 16 projects, 13 were focused on ammonia (two were for DME, one looked at ethanol). I’ve introduced here the eight that deal with fuel synthesis – the other six (including FuelCell Energy’s project) were dedicated to developing new ways to release hydrogen from ammonia or to use ammonia directly in a fuel cell to generate power. You can learn more details of those projects by reading about the REFUEL Ammonia Use-Side Funding Awards.