Green Ammonia Plant

Summary

Ammonia is a widely used industrial chemical, primarily in fertilizer production, and is also gaining attention as a potential carbon-free energy carrier due to its high hydrogen content and established global distribution infrastructure. However, conventional ammonia production is heavily dependent on fossil fuels, particularly through steam methane reforming, which results in significant greenhouse gas emissions. As a result, there is growing interest in alternative low-carbon production pathways.

This project focuses on the design and simulation of a green ammonia production process powered by renewable electricity. Hydrogen is produced through water electrolysis and subsequently combined with nitrogen in a Haber-Bosch-based catalytic synthesis loop to produce ammonia. The objective of the work is to develop a technically consistent and economically evaluable plant design that can be used for preliminary investment assessment.

Technical Approach/Methodology

The project combines process design, simulation, optimization, and economic evaluation to assess the feasibility of a green ammonia production facility. The work began with the development of process flow diagrams to determine the overall process configuration and define the major process units and material flows. A site selection study was then conducted to evaluate potential plant locations based on transportation infrastructure, utility availability, labor resources, and economic incentives. The process utilizes proton exchange membrane electrolysis to produce hydrogen from purified water and an air separation unit to supply nitrogen. These streams are then combined in a Haber-Bosch synthesis loop to produce ammonia. The facility was designed to produce approximately 161,177 metric tons of anhydrous ammonia per year while operating 8,000 hours annually.

AVEVA PRO/II was used to simulate the process and generate heat and material balances, establishing stream compositions, operating conditions, and energy requirements throughout the facility. The simulation results were used to size major equipment, including compressors, pumps, vessels, and heat exchangers. The process was designed with an electrical demand of approximately 221.6 MW, equivalent to roughly 11,000 kWh per metric ton of ammonia produced.

Aspen Energy Analyzer was used to perform pinch analysis and optimize the heat exchanger network to improve energy efficiency through heat recovery. The analysis identified minimum heating and cooling utility requirements of approximately 7.1 MW and 10.3 MW, respectively. Aspen Capital Cost Estimator was used to estimate capital costs, while operating costs, cash flow, NPV, and IRR were evaluated through a detailed economic analysis. The completed design was then assessed from technical, safety, environmental, and economic perspectives.

Outcomes

The project designed a green ammonia plant that is expected to produce 161,177 MT of anhydrous ammonia annually. Due to its strong transportation access, well-developed utilities, mature industrial infrastructure, and export capabilities, the plant was ultimately located in the Port of Victoria, Texas. The PRO/II simulated process consists of three main parts: hydrogen production process, nitrogen supply process, and an ammonia synthesis process. All major equipment sizing was based on simulation results and designed using Aspen.

The plant has fixed capital costs of $802 million and annual operating costs of $722 million. It cannot generate positive cash flow under current technology and economic assumptions. Therefore, the project is not yet economically feasible for commercialization. The analysis shows that the large amount of electricity required for PEM electrolyzers and the unit price of liquid nitrogen are the main factors affecting economic performance. Therefore, reducing energy and raw material costs is critical to improving the economic viability of green ammonia production. One promising strategy is to collaborate with government agencies to secure renewable energy subsidies and clean energy tax incentives, which could help lower the cost of electricity. In addition, because liquid nitrogen contributes significantly to raw material costs, future work should consider installing an on-site nitrogen separation unit. On-site nitrogen production could reduce raw material purchasing costs, improve supply stability, and decrease the impact of market price fluctuations on plant operation.

Project Media

Project Poster