Green Ammonia Production Research Articles

Waste-to-Ammonia: A sustainable pathway for energy transition

Ammonia, with its exceptional storage and transportation characteristics, emerges as a promising hydrogen carrier that can play a crucial role in this transition. This study investigates the techno-economic and environmental feasibility of utilizing produced water (PW), a waste product in oil and gas production, for ammonia production (AP). Accordingly, three distinct scenarios of utilizing the PW to produce ammonia are analyzed: i) fossil fuel-based (FF) AP without CO2 capture (gray), ii) FF-based AP with CO2 capture module (blue), and iii) a solar-thermal based AP (green). Results suggest that the blue system offers a compromise between environmental impact and economic feasibility, achieving a significant reduction in CO2 emissions of 0.605 kg CO2/kg NH3 compared with the 1.87 kg CO2/kg NH3, where gray, blue, and green AP are associated with the values of $435.63/tNH3, $480.41/tNH3, and $955.05/tNH3, respectively. Moreover, this study highlights the influence of carbon tax policy on the cost of the FF-based gray systems, while becoming unprofitable above $104.75/tCO2. Analysis of AP costs across shale formations reveals variations in product cost with salt concentrations, with the Bakken and Haynesville formations exhibiting the highest cost per ton of ammonia of $433 and $426/tNH3 for blue and gray systems, respectively. Notably, it is observed that the formations with high solar radiation and low salinity including Permian and Niobrara show potential for green ammonia with payback periods of 13 and 15 years, respectively. This can be used as reliable benchmark to propose a model for achieving sustainable society.

Synthesis of 2D nanosheet FePS3 electrocatalyst via salt-template method for electrochemical green ammonia production

Synthesis of 2D nanosheet FePS3 electrocatalyst via salt-template method for electrochemical green ammonia production

Light-driven nitrogen fixation routes for green ammonia production.

The global goal for decarbonization of the energy sector and the chemical industry could become a reality by a massive increase in renewable-based technologies. For this clean energy transition, the versatile green ammonia may play a key role in the future as a fossil-free fertilizer, long-term energy storage medium, chemical feedstock, and clean burning fuel for transportation and decentralized power generation. The high energy-intensive industrial ammonia production has triggered researchers to look for a step change in new synthetic approaches powered by renewable energies. This review provides a comprehensive comparison of light-mediated N2 fixation technologies for green ammonia production, including photocatalytic, photoelectrocatalytic, PV-electrocatalytic and photothermocatalytic routes. Since these approaches are still at laboratory scale, we examine the most recent developments and discuss the open challenges for future improvements. Last, we offer a technoeconomic comparison of current and emerging ammonia production technologies, highlighting costs, barriers, recommendations, and potential opportunities for the real development of the next generation of green ammonia solutions.

Two-stage low-carbon economic dispatch of an integrated energy system considering flexible decoupling of electricity and heat on sides of source and load

Under the goal of "double carbon", in order to further enhance the level of new energy consumption and solve the problem of restricting the flexibility of the system by "ordering power by heat" of combined heat and power (CHP) units, a low-carbon economic planning strategy with flexible decoupling of electricity and heat is proposed, by introducing a new type of electric-thermal coupling equipment on both sides of the source and load. Firstly, Consideration of the low-carbon and environmentally friendly characteristics of green ammonia production and ammonia-doped combustion technologies, a wind power(WT) – power to ammonia(P2A) - CHP units - thermal power (TH) units joint operation strategy is proposed on the source side. This strategy realizes the conversion of abandoned wind to green ammonia to ammonia coal hybrid generation, the decoupled operation of CHP units and promotes the consumption of wind power and the low-carbon operation of the system. Secondly, A dynamic incentive demand response model is developed to meet the demand of high proportion distributed PV in situ consumption on the load side. The dynamic incentive price guides the distributed power-to-heat load to change the response capacity, tracks the abandonment of wind and light, realizes the flexible conversion of power and heat load, and cooperates with the source side to promote the coupling operation of electric pyrolysis. On this basis, consider the flexible decoupling capability of electric-heat coupling equipment on both sides of the source and load to establish a two-phase low-carbon scheduling model for the day-before and day-after phases. In the day-ahead phase, the source-side electric-thermal-ammonia joint operation strategy is considered, and the electric and thermal energy supply plans are adjusted centrally; In the intra-day phase, the flexible adjustment range of power-to-heat devices and the heat load inertia on the load side are taken into account, and the electricity and heat planning strategies are adjusted in a distributed-centralised manner in conjunction with the source side. Finally, through the simulation of different cases, the results show that compared with the traditional electric heating system, the total cost of the system considering the scheduling strategy proposed in this paper decreases by ￥826,900, the carbon emission decreases by 1.2t, and basically realises the consumption of wind power and distributed photovoltaic power output. The proposed scheme reduces carbon emissions, promotes the consumption of wind power and distributed photovoltaic output, and is able to reach the goal of low-carbon economic dispatch.

Techno-economic and environmental assessment of green hydrogen and ammonia production from solar and wind energy in the republic of Djibouti: A geospatial modeling approach

This study conducts a thorough economic and technical analysis to assess the viability of green hydrogen and green ammonia production using renewable energy sources in the Republic of Djibouti. We explore the economic competitiveness of utilizing wind and solar power for sustainable energy production through various measures including levelized cost of energy (LCOE), hydrogen (LCOH), and ammonia (LCOA). Our analysis incorporates sensitivity assessments and Monte Carlo simulations to predict financial feasibility and environmental impact, focusing on CO2 emission reductions. A cost mapping of electricity, green hydrogen, and green ammonia from solar and wind resources was created to find Djibouti's most cost-effective production sites. The feasibility of exporting green ammonia to neighboring countries with high fertilizer demand was also evaluated using rail and truck transport scenarios. Key findings demonstrate that Moulouhlé, endowed with robust wind and solar resources, presents a strategic site for deploying renewable energy technologies. Wind energy, with a lower LCOE of 0.066 $/kWh compared to solar's 0.093 $/kWh, emerges as a more cost-effective solution for both hydrogen and ammonia production. Notably, wind-powered hydrogen production costs are 2.25 $/kgH2, significantly lower than solar-powered costs at 4.17 $/kgH2. In terms of green ammonia, wind power achieves production costs of 399.76 $/tonNH3, outperforming solar power which stands at 537.11 $/tonNH3. Additionally, our study evaluates the logistics of exporting green ammonia, determining rail transport as a more economically viable option than trucking. This research not only underscores Djibouti's potential as a leader in green energy exportation but also aligns with global decarbonization efforts, showcasing significant CO2 savings—154.94 Mt annually from wind. This work emphasizes the importance of strategic resource utilization in Djibouti, offering insights critical for stakeholders in making informed decisions about investing in renewable energy infrastructures. The outcomes suggest a promising future for regional energy sustainability and economic resilience, fostering a transition towards low-carbon energy systems.

Low carbon collaborative planning of integrated hydrogen-ammonia system and power distribution network

The conversion of renewable energy into chemical energy carriers, such as ammonia, enhances the accommodation of renewable energy for power distribution networks (PDN) and supports the decarbonization for ammonia production systems (APS). This paper addresses the integration of PDN with APS through a collaborative planning considering a carbon emission flow (CEF) model. A collaborative planning model with carbon emissions constraints is designed, and a sensitivity analysis is performed to evaluate the impact of varying renewable energy costs on the system. To further reduce carbon emissions from green ammonia production and stabilize renewable energy volatility, a nodal CEF model that incorporates energy storage systems (ESS), wind turbines (WT), and photovoltaics (PV) is proposed. The economic feasibility of the proposed model is verified via comprehensive experiments. Numerical results show that collaborative scheduling reduces both costs and carbon emissions in PDN and APS. Implementing a carbon tax encourages the transition from grey to blue ammonia production, while a decrease in renewable energy costs further promotes the shift from blue to green ammonia. Besides this, the analysis indicates that integrating long-term operation of WT and PV, together with low-cost renewable electricity and ESS, boosts the economic efficiency of the green ammonia production system.

Investigation of low carbon emission and high thermal efficiency of diesel engine combined with high-pressure direct injection of hydrogen carrier: Ammonia

Ammonia, as a zero-carbon fuel, has the potential to serve as a medium for the production, transportation, and utilization of clean energy. The scaling up of green ammonia production also necessitates broader utilization channels for ammonia. Applying ammonia as a fuel in engines is an effective way to reduce carbon emissions. This paper employs dual direct injection technology of ammonia and diesel in a novel ammonia-fueled engine to implement various control strategies and investigates their effects on combustion and emission performance. The results indicate that when the ammonia injection timing is advanced from −40°CA ATDC to −60°CA ATDC, the flash boiling of liquid ammonia decreases the indicated thermal efficiency (ITE) below 39% and increases unburned gas emissions. Globally, injecting ammonia during the intake stroke could receive better performance. Split injection strategies of diesel significantly improve the ITE, especially under a higher pilot-injection ratio of 75%. Additionally, increasing the load benefits the ammonia combustion process. Raising the IMEP to 12 bar improves ammonia combustion efficiency to over 95%, with an ITE reaching 49%.

Land Suitability Analysis for Green Ammonia Unit Implementation in Morocco Using the Geographical Information System–Analytic Hierarchy Process Approach

Morocco contains one of the greatest phosphate deposits and is the second-largest international phosphate fertilizer producer. However, it heavily relies on imported grey ammonia. To reduce this dependency, a paradigm shift is required toward local green ammonia production to strengthen the fertilizer industry. The purpose of the study is to identify the most promising locations in Morocco for hosting a green ammonia unit through a land suitability analysis. This was carried out using multi-criteria decision-making (MCDM) and geographical information systems (GIS). Eight relevant criteria were considered, based on carefully studying the relevant literature and consultation with renewable energy experts and professionals. The land suitability analysis revealed high suitability locations and five sites were selected from the regions of Dakhla, Laayoune, Boujdour, and Tarfaya. These locations were introduced to Hybrid Optimization of Multiple Electric Renewables (HOMER) software 3.16.2 for simulation. The simulation findings showed that the levelized cost of hydrogen (LCOH) ranges from 1.67 USD/kg to 1.82 USD/kg, with the lowest LCOH at Dakhla. The corresponding levelized cost of ammonia (LCOA) ranges from 646 USD/t to 687 USD/t. Dakhla was identified as the location with the lowest LCOA, accounting for 646 USD/t. The outcomes showed a similar trend compared to other studies (Saudi Arabia, Jordan, Iran). Considering improvements in the electrolyzer’s efficiency and cost, a technical and financial sensitivity analysis was conducted, identifying highly promising LCOA in Morocco, reaching 548 USD/t.

Electrocatalytic reduction of nitrate to ammonia over activated carbon-supported copper-iron bimetallic catalyst synthesized by hydrothermal co-precipitation method

Ammonia synthesis via electrocatalytic reduction of nitrate is a promising approach for green ammonia production. However, this process limited by multiple reaction pathways and NO3− adsorption over electrocatalyst surface. Herein, copper-iron bimetallic catalysts with different atom ratios of Cu/Fe (Cu/Fe = 10/0, 7/3, 5/5, 3/7 and 0/10) and activated carbon as supporter (CuFeOx/AC) were synthesized through hydrothermal co-precipitation method for catalytic reduction of nitrate. Synergistic effects between the Cu and Fe were observed in the copper-iron bimetallic catalysts and an appropriate atom proportion of Cu/Fe was benefit to accelerate the adsorption and electrocatalytic kinetics of nitrate reduction to *NO2 and *NO2 hydrogenation to·NH3 through electron redistribution. The catalyst of 7Cu3FeOx/AC presented the best catalytic performance in nitrogen electroreduction reaction for ammonia synthesis, with an NH3 yield rate of 2091 μg h−1 mgcat−1 and a faradaic efficiency of 76 % at −0.8 V vs. reversible hydrogen electrode. The 7Cu3FeOx/AC also exhibited excellent cycle ability and long-term durability whose NH3 yield rates maintained as high as 1476 and 2326 μg h−1 mgcat−1 after 9 cycles and 10 h durability measurement, respectively. The nitrate reduction behavior over 7Cu3FeOx/AC proceeded with a series of deoxygenation reactions as follows: NO3− → *NO3 → *NO2 → *NO → *NOH → *NH2OH →·NH3. With the above excellent properties, the 7Cu3FeOx/AC may prove to be a promising electrocatalyst for ammonia synthesis via nitrogen electroreduction reaction.

Thermochemical production of ammonia via a two-step metal nitride cycle - materials screening and the strontium-based system.

Ammonia synthesis via the catalytic Haber-Bosch process is characterized by its high pressures and low single-pass conversions, as well as by the energy-intensive production of the precursors H2 and N2 and their concomitant greenhouse gas emissions. Alternatively, thermochemical cycles based on metal nitrides stand as a promising pathway to green ammonia production because they can be conducted at moderate pressures without added catalysts and be further driven by concentrated solar energy as the source of high-temperature process heat. The ideal two-step cycle consists of the nitridation of a metal to form a metal nitride, followed by the hydrogenation of the metal nitride to synthetize NH3 and reform the metal. Here, we perform a combined theoretical and experimental screening of mono-metallic nitrides for several candidates, namely for Sr, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, Li, and Al. For the theoretical screening, Ellingham diagrams and chemical equilibrium compositions are examined with thermodynamic data derived from density function theory computations. For the experimental screening, thermogravimetric runs and mass balances supported by on-line gas analyses are performed for both steps of the cycle at ambient pressure and over the temperature ranges 100-1000 °C for nitridation and 100-500 °C for hydrogenation. The strontium-based cycle is selected as a reference for detailed examination and shown to synthetize NH3 at 1 bar by effecting the nitridation at 407 °C (at peak rate) and the hydrogenation at 339 °C (at peak rate). The co-formation of metal hydrides (SrH2) and metal imides (Sr2HN) are shown to help close the material cycle.

(Invited) Green Ammonia Production from Electrochemically Upcycling Waste Nitrogen in an Membrane-Free Alkaline Electrolyzer

NH3 is an essential nutrient for life, but its production through anthropogenic N2-fixing process has caused alarming damages to ecosystems and human health. Excessive NO3 - leakage into water bodies due to overfertilization has led to the formation of "dead zones" in coastal areas. Denitrification generates N2O, which is 300 times more potent than CO2. Restoring the balance between the generation and elimination of Nr is an urgent task for humanity. Efforts to address the negative impact of human-generated Nr have focused on converting it to harmless N2 or improving its utilization in the nitrogen cycle. One promising method is electrochemical conversion, which can eliminate Nr without additional oxidants/reductants. However, achieving selective NO3RR toward N2 is challenging. An alternative approach is to convert other forms of Nr to NH3 in an electrochemical reactor, which could reduce the environmental impact of Nr and decrease the NH3 demand from the Haber-Bosch process, while also reducing the use of fossil-derived H2.In this work, we report our work on the development of a membrane-free alkaline electrolyzer (MFAEL), which transforms Nr into NH3 as the sole N-containing product. With the inexpensive and robust MFAEL system, we achieved an ampere-level partial current density towards NH3 production. By properly choosing the conditions of NH3 collection from MFAEL, continuous production of pure NH3-based chemicals can be realized without the need for additional separation procedures. Techno-economic analysis (TEA) suggests the potential economic feasibility of the waste-to-NH3 process by coupling electrodialysis (ED) for Nr concentration and the MFAEL process for Nr conversion, offering an all-sustainable route for upcycling waste N into the highest-demanded N-based chemical product. Our recent efforts on green-ammonia capture CO2 and reduction to valuable chemicals will also be briefly presented.

Application of water electrolysis for green ammonia production: a plant simulation study

Application of water electrolysis for green ammonia production: a plant simulation study

Waste heat recovery from a green ammonia production plant by Kalina and vapour absorption refrigeration cycles: A comparative energy, exergy, environmental and economic analysis

The production of green ammonia involves significant energy penalties due to heat losses. Recovering this heat can enhance the sustainability of ammonia production. However, this area remains largely unexplored, making it unclear which approach to waste heat recovery is best suited. Therefore, this paper investigates two methods of waste heat recovery in a green ammonia production plant: the Kalina Cycle (KC) and the Vapour Absorption Refrigeration Cycle (VARC). The underlying processes are simulated, and an analysis is conducted covering energy, exergy, environmental, and economic aspects. The results show that integrating the system with KC yields a marginal energy efficiency improvement of about 1%. However, when the conventional ammonia production system is integrated with VARC, the improvement in energy efficiency reaches 8%, while exergy efficiency improves by 11%. An environmental assessment estimates the greenhouse gas emissions saved by each heat recovery method, revealing that VARC achieves almost four times the emission savings compared to KC. Economically, integrating KC increases the levelized cost of ammonia (LCOA) by over 18%, whereas adding VARC has almost no impact on the LCOA. Overall, the co-production of refrigeration using VARC is identified as a superior heat recovery technique for green ammonia plants.

Insight into Fluoride Additives to Enhance Ammonia Production from Lithium-Mediated Electrochemical Nitrogen Reduction Reaction.

Demands for green ammonia production increase due to its application as a proton carrier, and recent achievements in electrochemical Li-mediated nitrogen reduction reactions (Li-NRRs) show promising reliability. Here, it is demonstrated that F-containing additives in the electrolyte improve ammonia production by modulating the solid electrolyte interphase (SEI). It is suggested that the anionic additives with low lowest unoccupied molecular orbital levels enhance efficiency by contributing to the formation of a conductive SEI incorporated with LiF. Specifically, as little as 0.3wt.% of BF4 - additive to the electrolyte, the Faradaic efficiency (FE) for ammonia production is enhanced by over 15% compared to an additive-free electrolyte, achieving a high yield of 161 ± 3nmol s-1 cm-2. The BF4 - additive exhibits advantages, with decreased overpotential and improved FE, compared to its use as the bulk electrolyte. The observation of the Li3N upper layer implies that active Li-NRR catalytic cycles are occurring on the outermost SEI, and density functional theory simulations propose that an SEI incorporated with LiF facilitates energy profiles for the protonation by adjusting the binding energies of the intermediates compared to bare copper. This study unlocks the potential of additives and offers insights into the SEIs for efficient Li-NRRs.

Time-Series Forecasting of Large-Scale Green Ammonia Production: An Intelligent Dynamic Modeling Case in the Inner Mongolia Area of China

Time-Series Forecasting of Large-Scale Green Ammonia Production: An Intelligent Dynamic Modeling Case in the Inner Mongolia Area of China

Green ammonia production via recycle membrane reactor: Experiment and process simulation

With the increasing demand for ammonia (NH3) and the environmental benefits, green and sustainable NH3 production has been urgently developed and is expected to replace the traditional Haber-Bosch (HB) process with high energy consumption and COx emission. In this work, a recycle membrane reactor (RMR) process where a catalytic reactor relates to a membrane separator in series and the retentate stream is recycled to the reactor was designed and executed to produce NH3, in which a Ru (10 wt%)/Cs/MgO catalyst and two membranes with different permeation properties and NH3 selectivity were used. By independently controlling the temperature of the reactor and membrane separator, the synthesized NH3 was selectively extracted from feed side to permeate side by Aquivion/ceramic composite and sulfonated (3-mercaptopropyl)trimethoxysilane membranes. Impressively, NH3 mole fraction was greatly increased from 0.01 of equilibrium state to 0.1–0.45 in permeate stream, which is ascribed to the permeation properties and NH3 selectivity of membrane at different temperatures. Moreover, a one-dimensional, isothermal, and plug-flow model was proposed to simulate RMR, which can be successfully applied to deeply understand the mechanism of RMR. Furthermore, a green NH3 production process based on RMR was simulated to give rationalized suggestions for the NH3 synthesis under mild conditions.

Process Simulation and Design of Green Ammonia Production Plant for Carbon Neutrality

Process Simulation and Design of Green Ammonia Production Plant for Carbon Neutrality

Gliding arc discharge in combination with Cu/Cu2O electrocatalysis for ammonia production

Highly efficient and green ammonia production is an important demand for modern agriculture. In this study, a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu2O electrocatalysis. In this method, NO x is provided by the gliding arc discharge and then electrolyzed by Cu/Cu2O after alkaline absorption. The electrical characteristics, the optical characteristics and the NO x production are investigated in discharges at different input voltage and the gas flow. The dependence of ammonia production through Cu/Cu2O electrocatalysis on pH value and reduction potential are determined by colorimetric method. In our study, two discharge modes are observed. At high input voltage and low gas flow, the discharge is operated with a stable plasma channel which is called the steady arc gliding discharge mode (A-G mode). As lowering input voltage and raising gas flow, the plasma channel is destroyed and high frequency breakdown occurs instead, which is known as the breakdown gliding discharge mode (B-G mode). The optimal NO x production of 7.34 mmol h−1 is obtained in the transition stage of the two discharge modes. The ammonia yield reaches 0.402 mmol h−1 cm−2 at pH value of 12.7 and reduction potential of −1.0 V versus reversible hydrogen electrode (RHE).

How to Achieve Flexible Green Ammonia Production: Insights via Three-Dimensional Computational Fluid Dynamics Simulation

How to Achieve Flexible Green Ammonia Production: Insights via Three-Dimensional Computational Fluid Dynamics Simulation

Oxygen Vacancy-Controlled CuOx/N,Se Co-Doped Porous Carbon via Plasma-Treatment for Enhanced Electro-Reduction of Nitrate to Green Ammonia.

The electrochemical nitrate reduction reaction (NO3RR) is of significance in regards of environmentally friendly issues and green ammonia production. However, relatively low performance with a competitive hydrogen evolution reaction (HER) is a challenge to overcome for the NO3RR. In this study, oxygen vacancy-controlled copper oxide (CuOx) catalysts through a plasma treatment are successfully prepared and supported on high surface area porous carbon that are co-doped with N, Se species for its enhanced electrochemical properties. The oxygen vacancy-increased CuOx catalyst supported on the N,Se co-doped porous carbon (CuOx-H/NSePC) exhibited the highest NO3RR performance with faradaic efficiency (FE) of 87.2% and yield of 7.9mg cm-2h-1 for the ammonia production, representing significant enhancements of FE and ammonia yield as compared to the un-doped or the oxygen vacancy-decreased catalysts. This high performance should be attributed to a significant increase in the catalytic active sites with facilitated energetics from strategies of doping the catalytic materials and weakening the N─O bonding strength for the adsorption of NO3 - ions on the modulated oxygen vacancies. This results show a promise that co-doping of heteroatoms and regulating of oxygen vacancies can be key factors for performance enhancement, suggesting new guidelines for effective catalyst design of NO3RR.