Utilizing aqua-ammonia as a clean and scalable fuel in steam power plants

Global electricity generation continues to rely heavily on fossil fuels, with coal as the largest single source and natural gas (NG) contributing a substantial, second-largest share. To decarbonize this sector, hydrogen and ammonia are being explored as alternatives to natural gas; however, both face significant challenges. Safe and cost-effective transportation of hydrogen remains unresolved, while ammonia is limited by issues of toxicity and corrosiveness. This study proposes and evaluates the use of aqua-ammonia (A-A)—a liquid mixture of ammonia and water—as a novel fuel for decarbonizing steam power plants. A-A offers key advantages over hydrogen and pure ammonia, including safer transport, reduced corrosiveness and toxicity, and compatibility with existing NG infrastructure. Despite these advantages, its potential as a large-scale fuel for power generation has not been explored in the open literature, and no prior work has assessed its integration across production, transmission, separation, and combustion stages. This work explicitly addresses this research gap by evaluating A-A as a fully integrated energy carrier for utility-scale steam power plants and by introducing the concept of simultaneous energy and water delivery through a single pipeline—an aspect absent from previous studies. Given that A-A is a clean fuel capable of transporting both energy and water simultaneously through a single pipeline, this research demonstrates that A-A can offer solutions to two critical challenges: (1) providing a clean, safe, and practical alternative fuel to fossil fuels, and (2) supplying the required water for power plants operation — which is one of the most significant barriers to the development of steam power plants and a pressing issue in regions suffering from water scarcity. The study provides the first thermodynamic assessment of a full-scale Rankine cycle operating on ammonia extracted from A-A, modelling of a 200 MW Rankine cycle plant, powered by ammonia extracted from A-A, using Engineering Equation Solver (EES). The base case achieved a gross thermal efficiency of 41.26% and net efficiency of 35.07%, surpassing comparable NG-fired plants. The model evaluates multiple operational parameters—boiler pressure, condenser pressure, extraction pressures, and off-design operation—to identify optimal conditions. A 15% ammonia concentration in A-A is found to triple the volumetric energy delivery compared to NG at typical pipeline pressures, while simultaneously supplying sufficient water to meet plant cooling and process demands. Separation of ammonia from water is examined via three methods: Full evaporation, ammonia boiling-based, and membrane, with the latter demonstrating the best integration with condenser heat recovery and minimal efficiency penalty (~1.2%). Lifecycle analysis indicates potential for near-zero CO₂ emissions using green ammonia, with total annual fuel demand estimated at 773,000 t. Overall, this study establishes—for the first time—the technical feasibility, infrastructural compatibility, and environmental viability of A-A as a next-generation energy carrier for low-carbon power generation. • A-A enables simultaneous energy and water delivery for steam-power decarbonization. • First utility-scale modelling of Rankine cycles powered by A-A derived ammonia. • 15% A-A triples NG energy density while supplying high-purity process water. • A-A powered Rankin cycle could achieve >41% efficiency surpassing gas fired plants. • Green A-A operation cuts up to 2.3 Mt. CO₂ annually from a 200 MW power plant.