Andrew Medgyesi | MEL Candidate | Dec 17, 2021.
Mentor: Omar Herrera, MeridaLabs;
Abstract
A comprehensive literature review of various established and emerging technologies to transform raw feedstocks into the end products ammonia and methanol has been conducted to provide an overview of useful information for macro production process design consideration. Given that there are numerous pathways that may step through one or more intermediate products, the technologies have been grouped by these intermediate products (eg. biogas, syngas, hydrogen, etc.) and further by technology family (eg. gasification, electrolysis, pressure swing adsorption, etc). These groupings provide organization for the tabular presentation of important but general process information as well as for mind-map visualizations of the technologies. Further, because the intermediate products should be viewed as the threads that can connect technologies, a non-comprehensive, general input and output diagram for each technology intermediate grouping is provided.
The overview of useful process information includes, as required: Description, Feedstock(s), Product(s), Production Scale, Operating Conditions, Efficiency, Catalyst(s), Chemical Equation(s), Advantages, Disadvantages, Tables, Figures, and Diagrams. Subsequently, the collected research has been drawn upon to propose a novel biomass to ammonia production process. The process utilizes dual-fluidized bed steam gasification, packed bed membrane steam methane reforming, and absorbent enhanced Haber-Bosch ammonia synthesis. A comprehensive review of this process was not possible given time constraints. It has been proposed chiefly as a demonstration of the use of the literature review in deriving novel process concepts.
Introduction
Renewable, sustainable energy generation is expected to be the fastest growing energy sector globally over the next two decades (Eckard, 2018). Increasing environmental concerns regarding greenhouse gas and air quality emissions associated with fossil fuel use coupled with market volatility are driving a powerful and accelerating transition toward alternative fuels. Countries worldwide are pledging to meet aggressive emissions targets to limit global warming and this necessitates the turning away from the combustion of fossil fuels as a mainstay of the global economy. This has caused a ripple effect from global and national levels through an increasing number of regional and local governments, communities, corporations and individuals where a shift in awareness and priorities is promoting renewable domestic energy supplies as a means of overcoming the drawbacks of fossil fuels. One particularly promising clean energy vector is hydrogen, due to its versatility in application and variety in sources. Hydrogen can be produced from a wide range of resources using different feedstock, pathways and technologies, including fossil fuels and renewable energy. The most common, cost competitive, and emitting production method of hydrogen, accounting for 96% of global totals (Al-Qahtani et al., 2021), is the reformation of fossil fuels into so-called grey hydrogen. While reformation processes can be paired with carbon capture and storage (CCS) technologies to mitigate emissions, producing so-called blue hydrogen, it comes at significant cost and has been shown to save only 9%-12% of emissions over grey hydrogen (Howarth & Jacobson, 2021). The remaining 4% of global hydrogen is produced primarily via electrolysis but also includes other thermochemical, biological, and photolysis processes. It is the search for potential within these processes, and the further synthesis of hydrogen into the valuable products ammonia and methanol as a demonstration and exercise, that has guided this project
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