2023-12-06 11:19:02
Within the framework of the energy transition, in order to decarbonize sectors of the economy such as industrial, energy or transportation, ammonia has emerged as an ideal energy vector, as it is a hydrogen carrier that can be transported and stored with ease. It constitutes the fundamental chemical building block of the fertilizer industry and is necessary to produce nitric acid, in addition to potentially being used in numerous energy applications as fuel.
However, in the production of ammonia it is possible to use either fossil fuels or renewable energies, so the use of one route or another, apart from the consequent impact on efficiency and environmental impact, has an associated cost that should be analyzed, according to alphGalileo.
With the objective of determining the economic competitiveness of the different modes of ammonia production projected to the year 2050, researchers from the Polytechnic University of Madrid have carried out a study carrying out the modeling, simulation and techno-economic evaluation of large-scale ammonia production plants (3,000 tons/day) from different routes. Through the results obtained, the research demonstrates that the renewable production alternative still has challenges to overcome to be competitive with the use of fossil fuels.
To carry out the simulation and techno-economic evaluation, this study in which researchers from the Higher Technical School of Industrial Engineers of the UPM and the Norwegian research organization SINTEF is based on the large-scale production of ammonia using natural gas, solid fuels (coal and biomass) and renewable energy (solar and wind) as primary energy sources. To achieve this, processes have been evaluated with reference technologies and advanced designs.
The processes that use reference technologies that use natural gas (with an assumed cost of €6.5/GJ) present a similar levelized cost of around €385/ton of NH3, while the advanced process with chemical loop switching technology (in English, GSR or “gas switching reforming”) manages to reduce the cost by 14%.
However, the production route with renewable energy (solar and wind) using PEM-type electrolyzers located in the south of Spain is approximately 50% more expensive than using natural gas with CO2 capture using conventional technologies. On the other hand, the synthesis of NH3 through the co-gasification of coal and biomass implementing CO2 capture technologies allows achieving negative emissions. Two reference processes using currently commercial GE and MHI gasification technologies reach a levelized cost of €391.5 and €410.1/ton, respectively.
On the other hand, advanced gasification processes, syngas treatment and membrane reactors to carry out the conversion of carbon monoxide into hydrogen make it possible to achieve a 15% cost reduction compared to the GE gasification process.
From this analysis it is deduced that ammonia production plants from solid fuels, despite having a higher capital cost, provide energy security because they use local and low-cost fuels (coal and biomass), which compensates a relatively higher levelized cost with respect to processes that use natural gas as primary energy due to supply uncertainty and high price volatility.
From renewable
On the other hand, “the renewable production route requires significant capital cost reductions to be competitive with technologies established from fossil fuels,” explains Carlos Arnaiz, researcher at the Higher Technical School of Industrial Engineers. “Due to the intermittent nature of solar and wind resources, intermediate storage of electricity and/or hydrogen is required to ensure stable production, which makes these systems significantly more expensive,” he adds.
With an informative and didactic purpose, this study allows different public and private agents to make decisions within the framework of the energy transition and establishes a technologically neutral reference framework on the production of ammonia as a future energy vector.
The research on ammonia production does not end here. Researchers from UPM and SINTEF have participated in a subsequent study, recently published, on the future of fuels and ammonia production costs. This new research shows, through a statistical analysis of the techno-economic variables for a natural gas importing region (Europe), that the production of green ammonia could only become competitive with respect to fossil fuels when there is a very abundant renewable resource. at low cost.
Green ammonia
Alternatively, the electrolytic production route with nuclear energy can be considered, avoiding the storage of H2 or batteries as it is a continuous source of energy, which could have an opportunity if the policies adopted ensure a reduced investment cost for nuclear plants. “In any case, it is critical to minimize the production costs of primary energy and the capital cost of electrolyzers,” says Arnaiz.
«In the case of renewable energy, hybridization with an alternative source of hydrogen without net CO2 emissions, such as biogas, would allow reducing the storage costs and required oversizing associated with the intermittency of the solar or wind resource, maintaining a low environmental footprint,” he concludes.
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