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January 28, 2025Decarbonizing Urea: Solutions for sustainability in agriculture
Urea is the most used and traded fertilizer in the world with over half of the world’s ammonia production being converted to urea. As a primary source of nitrogen for crop nutrition, urea is used in many parts of the world, and its demand is heavily driven by food production industries. Traditionally urea is produced by synthesizing ammonia through the energy-intensive Haber-Bosch process, followed by reacting ammonia with carbon dioxide (CO2) to produce urea. This process relies heavily on fossil fuels such as natural gas, coal or oil, resulting in significant carbon dioxide emissions. Additionally, the growing global population has created substantial pressure to meet increasing food demands, driving a similar increase in the demand for urea fertilizer. In response, alternative urea production technologies are being developed with the aim of reducing environmental impacts compared to conventional methods.
Currently, decarbonization in the urea industry is centered around reducing the consumption of energy and utilities within the production process. Utility emissions, particularly that of steam, are a large contributor to carbon intensity. A large proportion of steam used in urea production is attributed to the stripper in which unconverted ammonia and carbon dioxide is separated from the aqueous urea solution. Various technological licensors such as Stamicarbon, Casale and TOYO Engineering have introduced improved configurations of their pre-existing technologies in recent years. Such configurations claim to have lower steam, cooling water or electricity consumption compared to their previous iterations.
Numerous studies have been undertaken to investigate other methods for urea synthesis, particularly those involving the application of non-fossil fuel-based feedstock and renewable energy, in order to reduce the carbon footprint associated with the production process. A flowchart showcasing potential pathways for sustainable urea production is illustrated as follows:
Ammonia Synthesis
The synthesis of green ammonia, or ammonia produced from renewable energy sources, involves two main processes:
- Electrolysis of water to obtain pure hydrogen
- Air separation to obtain pure nitrogen
Hydrogen is produced through the electrolysis of water using electricity generated from renewable sources like solar or wind. This process splits water into hydrogen and oxygen after which the hydrogen is purified to obtain a pure gas. For continuous operation the solar or wind-powered electrolyzer is typically connected to the electrical grid. During periods of high renewable energy generation, surplus electricity can be supplied to the grid and later imported during times of lower energy production.
Nitrogen is obtained through an air separation unit (ASU) such as cryogenic separation, membrane separation or pressure swing adsorption (PSA). The resulting nitrogen and the pure hydrogen obtained from electrolysis reacts together via the Haber-Bosch process to form ammonia.
Carbon Dioxide Sourcing
In a conventional integrated urea plant carbon dioxide is normally sourced from the hydrogen synthesis process, for example steam methane reforming during ammonia production. Alternative methods that could be utilized to obtain carbon dioxide nclude:
- Carbon capture – This approach is defined as the separation of carbon dioxide from gas mixtures emitted by large, fixed-point sources, such as flue gases from power plants or industrial facilities. Carbon capture technologies are classified into pre-combustion or post-combustion systems, depending on whether carbon (in the form of CO2) is removed before or after the fuel is burned. Once captured from whichever process it is being emitted, the recovered carbon dioxide may then be utilized as feedstock to produce urea.
- Direct air capture (DAC) – In this method, carbon dioxide is removed directly from the atmosphere to reduce its atmospheric concentration levels and to offset emissions from difficult to decarbonize sectors. While DAC has gained increasing attention in recent years due to global decarbonization efforts and net-zero goals, its high energy consumption and significant capture costs have led to hesitancy in widespread adoption and investment.
- Gasification of bio-based feedstock – Biomass or municipal solid waste (MSW) undergoes gasification at high temperatures to produce syngas, comprising mainly of carbon monoxide and hydrogen gas. Following purification of the syngas stream, the hydrogen may be used in ammonia synthesis, while the carbon monoxide undergoes a shift reaction to produce carbon dioxide.
Future Outlook
The application of non-fossil fuel-based feedstocks and renewable energy to produce sustainable urea seems promising, as it has the potential to support decarbonization efforts in the agricultural sector, lower greenhouse gas emissions and handle the challenges of food security. However this also presents its own unique set of challenges.
Typically urea is produced from synthetic ammonia and carbon dioxide. Most ammonia that is produced today is considered grey ammonia or ammonia produced from hydrogen derived from natural gas using the Haber-Bosch process. A lower-carbon alternative to grey ammonia is blue ammonia, which incorporates carbon capture processes to capture the carbon dioxide emissions generated during ammonia production, despite also using natural gas as a feedstock.
In green ammonia plants however, carbon dioxide is obtained from other sources such as biomass or direct air capture (DAC). While such methods have been investigated they are often only produced in very small capacities resulting in poor economies of scale and high capital intensity. Hence, such efforts have presently not reached commercialization status as they are not economically feasible.
Certain regulations and mechanisms may make low-carbon production technologies for urea more competitive, such as the EU's Carbon Border Adjustment Mechanism (CBAM) which is expected to be phased in by 2026. Under this mechanism, importers of high carbon intensity urea are required to purchase certificates to offset the carbon emissions generated during production, improving the cost competitiveness of green and/or low carbon intensity urea.
Overall however, further research and development is required before greener production pathways for urea can be pursued and comprehensively utilized at a larger scale. Potential approaches include developing more efficient carbon capture facilities, solar cells or wind turbines, water electrolysis systems and improved catalysts for urea synthesis. Continuous improvements in urea separation and recovery from lower concentration solutions are also promising directions.
Find out more...
TECH Program: Urea (2024 Program)
Urea is the most used and traded fertilizer in the world; its demand is heavily driven by the fertilizer and food production industries as urea is used in many parts of the world as the primary source of nitrogen for crop nutrition. This techno-economic report reviews the chemistry, properties, technology, and development trends of urea. The report provides urea economics for several different global locations (USGC, China, Western Europe, and Middle East) under a consistent first quarter 2024 price scenario.
TECH Program: Ammonia (2024 Program)
This report explores the transformative potential of ammonia and how it is poised to revolutionize fertilizer, marine fuel, power generation, and hydrogen transport. The report includes discussion of the latest advancements in ammonia production technologies, from traditional methods to groundbreaking green and blue alternatives, and provides an in-depth look at the traditional Haber-Bosch process and emerging methods like electrolysis. Analysis of cost of production drivers and economic viability of various ammonia production routes, and examination of the carbon footprints associated with different ammonia production technologies is included. Insights into the latest innovations and future trends in ammonia production and applications are also discussed.
TECH Program: Direct Air Capture Technologies (2023 Program)
This TECH report provides an overview of Direct Air Capture (DAC) technology and economics, as well as market aspects and climate landscape in terms of key policies and project status. This includes DAC technology process descriptions, key challenges and limitations, advantages and disadvantages, and areas for cost-reducing innovation. The report primarily focuses on sorbent- and solvent-based DAC approaches, with a minor focus on other developmental DAC methods such as moisture/humidity swing adsorption, cryogenic, electrochemical/electro-swing adsorption, and membrane-based DAC technologies. In addition, this report discusses key players and technology holders/licensors of DAC technology and includes base-case cost of CO2 capture estimates for sorbent- and solvent-based DAC processes.
TECH Program: Carbon Capture and Sequestration (CCS) Technologies (2022 Program)
This TECH report provides an overview of the technological, economical and market aspects of carbon capture and sequestration, as well as climate landscape in terms of key policies and project status.
The Authors...
Jesse Chung, Consultant
Christopher Ho, Senior Analyst
About Us - NexantECA, the Energy and Chemicals Advisory company is the leading advisor to the energy, refining, and chemical industries. Our clientele ranges from major oil and chemical companies, governments, investors, and financial institutions to regulators, development agencies, and law firms. Using a combination of business and technical expertise, with deep and broad understanding of markets, technologies and economics, NexantECA provides solutions that our clients have relied upon for over 50 years.
