Ammonia is a globally indispensable chemical commodity because it serves as the foundational building block for agricultural fertilizers. Without it, commercial farming operations could not sustain the food supply required for the general population. It is also becoming a vital, carbon-free energy carrier used to transport hydrogen cleanly across the world. Traditional "grey ammonia" relies on burning fossil fuels, like natural gas or coal, to extract the hydrogen needed for the process. Because this current method is so heavily dependent on hydrocarbons, it releases massive amounts of carbon dioxide, making the chemical industry a huge contributor to global greenhouse gas emissions. This project designs a "green ammonia" facility that completely eliminates fossil fuels from the production lifecycle. Instead of reforming hydrocarbons, the plant uses clean thermal and electrical energy from small modular nuclear reactors to power high-temperature steam electrolysis, splitting water into clean hydrogen. This hydrogen is then combined with nitrogen to create a 99.6 mol% pure ammonia product with zero direct operational carbon emissions. This project affects the general population by lowering carbon emissions, which helps curb global warming and leads to a greener Earth.
Green Ammonia Plant
Summary
Technical Approach/Methodology
We solve this problem by integrating process design, simulation, optimization, and economic evaluation to assess the technical and financial viability of a zero-carbon green ammonia production facility. The project began with the development of process flow diagrams to establish the overall configuration, defining the major process units and material flows. A site selection study was then conducted to evaluate potential locations based on transportation infrastructure, utility availability, labor resources, climate risks, and regulatory oversight. Rather than conventional reforming, the process utilizes clean thermal and electrical energy from four XE-100 high-temperature gas-cooled small modular nuclear reactors (SMNRs) to power a Solid Oxide Electrolyzer Cell (SOEC) system. The SOEC splits demineralized water into high-purity green hydrogen, which is dried via temperature swing adsorption and blended with a high-purity nitrogen stream sourced from an off-site air separation unit. These streams are combined in a high-pressure Haber-Bosch synthesis loop to create the final product. The facility is designed to produce 201,719 metric tons of green ammonia per year at a product purity of 99.6 mol%.
AVEVA PRO/II was utilized to simulate the process and generate rigorous heat and material balances, establishing stream compositions, flow rates, operating conditions, and unit duties throughout the plant. The simulation results provided the necessary technical baseline to size major equipment, including multi-stage reciprocating compressors, process pumps, vertical and horizontal separation vessels, and heat exchangers. The facility's high-temperature steam electrolysis system requires an immense electrical load, consuming approximately 37.5 kWh per kilogram of hydrogen produced to yield a total rated electrical demand of roughly 174 MW for the electrolyzer arrays alone. To maximize energy efficiency, Aspen Energy Analyzer was used as a starting point to perform pinch analysis and map out heat exchanger networks. This was paired with manual process optimization to implement extensive heat recovery around the high-temperature SOEC and exothermic Haber-Bosch systems. By capturing sensible heat from hot process streams to preheat incoming feeds and convert boiler feed water into steam, the design generates an additional 65,000 pounds of steam per hour from the hydrogen production unit and 33,100 pounds of steam per hour from the synthesis loop, significantly driving down external utility demands.
Following the technical layout, Aspen Capital Cost Estimator and detailed engineering models were used to construct a definitive commercial cost basis and project cash flows over a 2-year construction period and 20-year operational lifetime. To evaluate the technical feasibility of this specific design, the simulation verified that the facility successfully hits its target capacity and 99.6 mol% purity under strict operating parameters. The plant is strategically located at the Pawnee Generating Station in Brush, Colorado. This brownfield site selection allows the facility to directly serve high-value agricultural fertilizer markets in the US Corn Belt while explicitly upcycling existing industrial assets—including established water rights, cooling water systems, and grid transmission lines—to minimize new construction and early capital expenditures.
Building upon the process design, a detailed economic analysis evaluated the financial viability of the project for commercial investment. The total capital investment required for the facility was estimated at approximately $6.28 billion, driven heavily by an Inside Battery Limits (ISBL) cost of $3.925 billion and an Outside Battery Limits (OSBL) cost of $1.570 billion for the advanced nuclear and electrolysis equipment. Operating expenses were compiled into a comprehensive cost of production, revealing a variable cost of production (VCOP) of $15.76 million per year for raw materials and a massive fixed cost of production (FCOP) of $405.89 million per year due to intense maintenance, labor, and overhead charges. Steady plant operations generate consistent annual revenues of $322.79 million from green ammonia sales. However, due to the immense upfront capital constraints, the project resulted in a deeply negative net present value (NPV) of -$4.97 billion at the end of the 20-year project life and negative internal rate of return (IRR) values, including an IRR of -34.9% at year 20.
By observing the projected cash flows, the facility maintains a stable, positive annual operating cash flow of roughly $186.5 million starting in year 4, which experiences a slight drop around year 14 when the 10-year straight-line depreciation period concludes and removes the project's tax shield. However, this annual return is insufficient to recover the multi-billion-dollar upfront capital investment, resulting in a simple payback period of 92.2 years—a timeline that far exceeds the operational lifespan of the plant. While current macroeconomic conditions and the high baseline costs of maturing SMNR and SOEC technologies render this specific project financially unfavorable today, it establishes a critical engineering foundation. The project demonstrates that large-scale green ammonia production via nuclear power is completely technically achievable and ecologically vital. Commercial viability will ultimately depend on future capital equipment cost reductions as these technologies mature, combined with aggressive carbon production tax credits and premium market pricing for low-carbon products relative to conventional grey ammonia.
Outcomes
To complete the final design and visual representation of the plant, an AVEVA PRO/II simulation, plot layout, PFDs, MSDs, P&ID, an HMB, and a simulated Line List were rigorously developed. These technical engineering resources were constructed under realistic operating conditions, mapping out the precise mass and energy balances across the facility. By organizing the facility into five detailed process units, the technical package provides a clear breakdown of how the entire plant functions as a single, cohesive system. Every phase of the engineering design reflects a standard industrial process basis, working backward from strict targets for plant capacity, feedstock conditions, and chemical purity. By integrating custom mathematical models into our simulations, we successfully balanced physical constraints with outside technical criteria to maximize overall unit efficiency. The resulting Front-End Engineering Design delivers an industrial-scale plant engineered to produce 201,719 metric tons of 99.6 mol% pure anhydrous ammonia annually.
A comprehensive economic evaluation was conducted to model the facility's cash flows over a 20-year operational life. This discounted cash flow analysis resulted in a net present value of -$4.97 billion and a simple payback period of 92.2 years, showing that the venture is not financially viable under current market forecasts. While the plant generates a steady annual operation cash flow of $186.5 million starting in year 4, these returns are heavily throttled by intense capital depreciation and are ultimately insufficient to recover the massive initial fixed assets. Consequently, implementing this specific model is currently unfavorable from a pure investment perspective without major structural or legislative adjustments.
To optimize the process economics, future design iterations should focus on integrating the facility's extensive waste heat networks. Currently, the system features unintegrated energy streams, generating an extra 65,000 pounds of steam per hour from the hydrogen production unit and 33,100 pounds of steam per hour from the ammonia synthesis loop. Rather than venting or leaving this high-temperature utility stream unutilized to avoid immediate equipment charges, this energy could be funneled into secondary power recovery loops or regional district heating. Capturing this sensible heat would lower external utility demands, creating a stronger financial profile for the plant's long-term operation.
The completed project establishes a fully integrated green chemical plant engineered for a steady annual capacity of 201,719 metric tons. After balancing land availability, localized labor rates, and strict regulatory hurdles, the plant was strategically sited at the Pawnee Generating Station in Brush, Colorado. The chemical process flows through four core technical steps modeled in PRO/II: nuclear steam generation, an advanced solid oxide electrolyzer cell stack, four-stage hydrogen compression/drying, and a high-pressure Haber-Bosch synthesis loop. Major vessels and equipment items were custom-sized using standard ASME vertical and horizontal separation parameters based directly on the simulation's line data.
With an estimated total capital investment of $6.28 billion against a capped annual product revenue of $323 million, the facility faces steep financial barriers to commercialization under traditional economic structures. The primary cost drivers stem from the massive upfront capital charges required to install next-generation small modular reactors and large-scale solid oxide electrolyzer cell arrays. To overcome these financial constraints, future work must focus on securing clean energy production tax credits and federal manufacturing subsidies to offset the initial capital burden. Additionally, as advanced nuclear modules and electrolyzer technologies mature globally, equipment supply chain costs will naturally scale down, transforming this technically sound design into a highly competitive, zero-emission alternative to conventional fossil-fuel chemical manufacturing.