(205c) Hydrogen Production from Municipal Solid Waste

Currently, disposal of municipal solid waste represents a significant societal problem. The increasing piles of waste in landfills pose significant hazards in terms of toxins, leachates, and greenhouse gases. One solution is to utilize the solid wastes as fuel to produce higher-value products. Solid fuels can be used to produce hydrogen via gasification to produce syngas using air or steam. Syngas produced by gasification is converted to CO₂ and H₂ via water gas shift reaction followed by CO₂ and H₂ separation for production of pure H₂. When air is used, the syngas produced is diluted with N₂ lowering the quality of the syngas while contributing to CO₂ emissions. When steam is used as the gasification medium in biomass gasification heat integration schemes such as use of inert heat carriers must be employed to provide heat for the endothermic gasification reaction. Oxygen produced by air separation is traditionally used for oxy-fueled coal gasification. On industrial scale, large amounts of oxygen are required and are typically produced by cryogenic separation from air, a process which requires a large CO₂ footprint, as well as significant capital and operating costs. Thus, the conventional process to utilize solid waste as raw material to produce high-value chemicals poses significant energy and environmental challenges.

Recently, researchers at the National Energy Technologies Laboratory (NETL)^[1],[2] have developed novel oxygen carriers for a three-reactor system with promising results using various solid fuels such as biomass, flax straw and MSW. They have also developed a new process to convert CO₂ to CO, allowing for the production of secondary products such as methanol. The main innovation is the development of a novel oxygen carrier process, which eliminates expensive air separation steps, water gas shift reactor and CO₂/H₂separation steps. The process does not require an external heat source eliminating heat integration issues and associated CO₂ emissions. An additional innovation is the fact that the oxygen carrier process operates below 900^oC, thereby eliminating the ash melting issues encountered in traditional gasification systems that operate above 900 ^oC. In this research, NETL’s bench-scale experimental results will be utilized to develop a simulation of a large-scale plant in the ASPENPlus environment that utilizes MSW as feed and produces H₂ as the primary product and methanol as a secondary product. This simulation will be utilized to conduct a techno-economic analysis of the entire process. The anticipated advantages of this novel process include lower H₂production costs and the utilization of waste materials as feed such as MSW instead of fossil fuels, resulting in a significant reduction in MSW quantities for disposal and increasing the capacity of the existing waste management infrastructure.

[1] R.V.Siriwardane and J. Riley, “Process for production of hydrogen with transport from chemical looping using mixture of partial oxidation oxygen carriers and combustion oxygen carriers”, S 166,257 filed Jan 12, 2022

[2] R. V. Siriwardane and Y. Fan, “Metal Ferrite Oxygen Carriers For Gasification Of Solid Carbonaceous Fuel,” U.S. Patent 10,030,204, July 24, 2018