Renewable production of ammonia and nitric acid

Abstract

Decarbonization of the power sector offers ammonia industry an opportunity to reduce its CO 2 emissions through sector coupling. Extending from our previous work, we propose a power-based process for ammonia and nitric acid production. The coupling of nitric acid production facilitates highly efficient heat integration between steam electrolysis and the rest of the process. We investigate the economic performance of the production complex through a model-based dynamic optimization approach, considering scenarios with or without incorporation of intermittent wind power as well as deployment of battery storage. In all cases, the wind power integration proves to be economic with a peak-to-base load ratio of up to 2.3. The new process reduces primary energy consumption by more than 13% compared to conventional technologies. However, it is only economically competitive with help of either a low-cost battery storage or a higher carbon price on fossil fuels. The results also confirm the importance of considering process dynamics during process design. K E Y W O R D S dynamic optimization, electrification, Haber-Bosch, process design, sustainability

Green ammonia as a spatial energy vector: a review

“…A third approach is the use of grid 73,74,85,90,98 or hydro 76,97 electricity to entirely supply the electrolyser and ammonia plant at almost all times, or whenever renewables are not available. Although this approach enables maximum value to be extracted from the installed capital equipment, and no costs to be allocated to hydrogen storage, it demands the use of either of hydroelectricity, whose global potential is far less than global demand, 99 or of prohibitively expensive grid electricity, which is not generally decarbonized.…”

“…Forecasting of electrolyser price is complicated by variations in the electrolyser scope. For instance, Wang et al 90 species a very low price of 100 USD per kW for a solid oxide cell (typically the most capital intensive cell type 71 ); however, this only includes the stack and excludes all balance of plant, as well as installation costs, which they do not specify. Lin et al 98 and Palys et al 94 both use a bare module cost (327 USD per kW and 637 USD per kW respectively) alongside published installation factors to estimate a project CAPEX (994 USD per kW and 1248 USD per kW).…”

Feasibility Analysis of Integrated Power-to-Ammonia Processes Employing Alkaline Electrolysis and Air Separation

“…Greenhouse gas emission were also considered and compared to those of the existing ammonia production process. Wang et al (2020) studied a power-based process for ammonia and nitric acid production, and case studies were performed according to di erent power-supply scenarios. A low battery price and high carbon price were required for the proposed process to be more competitive than the typical process.…”

Harnessing the Wind Power of the Ocean with Green Offshore Ammonia

“…The predominant process for producing green ammonia uses renewable electricity to power water electrolysis and air separation that produce hydrogen and nitrogen, respectively, which are then reacted to ammonia in the Haber-Bosch process . Existing studies focus on several important process optimization aspects, including reducing the cost of water electrolysis, process intensification for ammonia synthesis, − modularization for distributed ammonia production, , and systematic process design and operation that take the intermittency of renewable energy sources into account. − While the initial motivation was mainly to decarbonize fertilizer production, more recently, green ammonia has attracted increasing attention due to its promise as a carbon-free energy carrier. As such, it can be used for energy storage to balance temporal and geographical mismatch between energy demand and supply.…”