ReMo Energy, an American cleantech startup founded in 2020, develops distributed ammonia production plants that can integrate with renewable energy sources to produce green hydrogen via water electrolysis for ammonia synthesis. ReMo Energy’s small-scale, modular plant can produce 100-400 metric tons of ammonia per day using lower-cost reactors and components than traditional ammonia plant architectures. The company is integrating ammonia synthesis with the production of downstream nitrogen fertilizers to decarbonize agriculture.
Challenges: green ammonia
Ammonia (NH₃) is a crucial compound for agriculture. In 2021, the global production of ammonia was 185 million metric tons, with over 80% being used for fertilizer production. As the global population increases, so does the demand for ammonia.
The primary method of ammonia production is the Haber-Bosch process, which converts pure hydrogen (H₂) and nitrogen (N₂) into ammonia. World-scale ammonia synthesis plants can produce up to 5,000 metric tons per day. They are usually situated in remote areas with cheap natural gas. The produced ammonia is transported considerable distances to customers and contributes to carbon emissions.
The Haber-Bosch process for ammonia synthesis requires high temperature and pressure (above 450 ºC and 200 bar, respectively), which are intentionally engineered for the iron-based catalysts to attain significant yields of ammonia. The energy-intensive nature of the process results in the consumption of about 2% of worldwide fossil fuels and annual emission over 420 million tons of carbon dioxide (CO₂). Production of ammonia contributes to 1.5% of global greenhouse gas emissions.
The traditional ammonia production process described above is not easily adapted and deployed for the production of green ammonia using green hydrogen feed via water electrolysis powered by renewable electricity of solar panels and wind turbines. The intermittent nature of solar and wind energy makes the rate of ammonia production not be able to be turned up and down because of the compressors required to achieve the high operating pressures.
Therefore, there is an urgent need to develop distributed, small-scale ammonia production plants that can be integrated with renewable energy sources to convert N₂ and green hydrogen into NH₃.
ReMo Energy Technology
ReMo Energy has developed a modular, distributed green ammonia production system that integrates with solar panels and wind turbines to generate green hydrogen (H₂) feed via water electrolysis for ammonia production at a low pressure of 80 bar. The low-pressure ammonia synthesis can match the delivery hydrogen pressure of an electrolyzer, thus eliminating the need for an expensive compressor. Furthermore, the low-pressure operation allows the development of a simple and low-cost ammonia synthesis reactor featuring a hot shell design, inexpensive heat exchange materials, and low-pressure oriented catalysts. ReMo Energy’s ammonia synthesis system can produce 100-400 metric tons per day.
ReMo Energy ammonia
The diagram below illustrates ReMo Energy’s ammonia production system.
The system includes an electrolyzer powered by renewable energy sources such as solar panels and wind turbines, an air separation unit, a de-oxygenation reactor, a dehydration unit, a single-stage compressor, an ammonia reactor, a condensation module coupled with a screw compressor, and an ammonia storage tank.
The electrolyzer can be a polymer electrolyte membrane (PEM) or an alkaline electrolyzer. It receives renewable electrical power from solar panels and wind turbines and converts water into hydrogen for ammonia synthesis. The delivery pressure of hydrogen matches the low pressure of the ammonia synthesis reactor. This eliminates a costly multi-stage centrifugal compressor and prevents the process from being rapidly turned up and down.
The pressure swing adsorber (PSA) separates nitrogen from the air and provides enriched nitrogen (80% mol) for ammonia synthesis.
The hydrogen and nitrogen streams are mixed to produce the raw synthesis gas stream, which contains oxygen and other minor impurities. Oxygen is removed by a de-oxygenation reactor that operates below 400 ºC and contains hydrogenation catalysts such as platinum or palladium. The effluent from the de-oxygenation reactor contains hydrogen, nitrogen, minor impurities, and the water generated by the combination of hydrogen and oxygen in the reactor.
Water needs to be removed from the synthesis gas because it can poison the ammonia synthesis catalyst. Therefore, the wet synthesis stream is dehydrated in a dehydration unit, which is operated in a Temperature Swing Adsorption (TSA) cycle.
The dry synthesis gas stream is pressurized to a low pressure of 80 bar using a single-stage compressor and fed into the ammonia synthesis reactor. The ammonia synthesis occurs via the chemical reaction with the iron oxide-based catalyst:
H₂ + N₂ ⇄ NH₃
In fact, ammonia synthesis is favored at high pressure. ReMo Energy’s low-pressure reactor leads to a low ammonia production yield. However, this disadvantage is compensated by other advantages:
(1) The ammonia production system can be integrated with renewable energy sources for producing low-pressure green hydrogen via water electrolysis. This eliminates expensive compressors.
(2) The low-pressure ammonia synthesis reactor is inexpensive. The reactor can have a hot shell and the catalyst can be in direct contact with a pressure vessel. This is in contrast to the more costly cold-shell reactors that separate the catalyst from the pressure vessel. The reactor may use low-cost heat exchange elements made of carbon or stainless steel placed in direct contact with the catalyst.
(3) The ammonia synthesis catalysts are designed for low pressure. These low-pressure catalysts are nanotubes or nanofibers with very large active surface areas.
The effluent of the ammonia synthesis reactor is cooled via a heat exchanger and condensed to a temperature of -20 ºC in a condensation module. The condensation module uses a screw compressor that evaporates and recompresses the ammonia.
The liquid anhydrous ammonia is then separated from the unreacted nitrogen and hydrogen in a gas-liquid separator. The unreacted hydrogen and nitrogen are pressurized and recirculated to the ammonia synthesis reactor. The final anhydrous ammonia product can be stored at ambient temperature at a pressure between 15 and 20 bar.
ReMo Energy Patent
- WO2023114890A1 Systems and methods for producing renewable ammonia
- CA3210865A1 Production of renewable ammonia
ReMo Energy Technology Applications
Green ammonia can be used as a carbon-neutral fertilizer, significantly reducing the carbon footprint of farming. Using green ammonia for fertilizer could drive down farming’s carbon footprint by as much as 90% for corn and small grain crops.
Green ammonia can be used as a transport fuel, replacing highly polluting gasoline, diesel, and propane to run engines, generators, and turbines. It has applications in transportation, including heavy goods vehicles, trains, aviation, and shipping.
Green ammonia has the potential to be used for large-scale, long-term energy storage. It has nine times the energy density of Li-ion batteries and three times that of compressed hydrogen, making it a competitive option against electrochemical batteries, pumped hydro, and capacitors to balance consumption and renewable generation. Countries including Japan, Australia, the Netherlands, and the United Kingdom have national plans to use green ammonia to store (and export) their renewable energy surpluses.
ReMo Energy Products
ReMo Energy’s ammonia synthesis system is designed for discontinuous operation and processing. The production rate of ammonia can be increased or decreased by at least about 10% per minute. The system can produce less than 200 metric tons of ammonia per day and consume less than about 50 megawatts of electrical power per year.
The company is integrating ammonia synthesis with the production of downstream nitrogen fertilizers to provide a turnkey solution for the manufacturing of green agricultural commodities.
ReMo Energy Funding
ReMo Energy has raised a total of $5.3M in funding over a Seed round on Jul 14, 2022.
ReMo Energy Investors
ReMo Energy is funded by 3 investors:
ReMo Energy Founder
Scott Rackey is Founder.
ReMo Energy CEO
Scott Rackey is CEO.
ReMo Energy Board Member and Advisor
Shally Shanker is Board Member.