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We also find that producing hydrogen from steam crackers creates less (15% to 91%) life-cycle greenhouse gas emissions than the conventional more » centralized steam methane reforming (SMR) pathway. We estimate that 3.5 million tonne/year of by-product hydrogen can be produced from steam crackers, almost doubling the size of the existing U.S. steam crackers, as well as the potential of by-product hydrogen production, is continuously growing. Benefiting from the shale gas boom in recent years, the overall production capacity of U.S. Steam crackers convert hydrocarbon feedstock (e.g., natural gas liquids) to light olefins via thermal cracking and produce hydrogen as a by-product during the process. These results improve those reported by conventional hydrogen production methods, such as steam reforming. When the nuclear power plant supplied the electrical power, low GHG emissions were obtained. The results show that the electric power, supplied to the hydrogen plant, is a sensitive parameter for GHG emissions. Particular attention was more » focused to those processes where there was limited information from literature about inventory data, as the TRISO fuel manufacture, and the production of iodine. The product system was defined by the following steps: (i) extraction and manufacturing of raw materials (upstream flows), (U) external energy supplied to the system, (iii) nuclear power plant, and (iv) hydrogen production plant. The LCA tool was used to quantify the impacts associated with climate change. The purpose of this paper is to quantify the greenhouse gas (GHG) emissions associated to the hydrogen produced by the sulfur-iodine thermochemical process, coupled to a high temperature nuclear reactor, and to compare the results with other life cycle analysis (LCA) studies on hydrogen production technologies, both conventional and emerging. This LCA gives us an overall picture of impacts across different environmental boundaries, and hence, can help in the decision-making process for implementation of the algae scenario. However, impact assessment for depletion of natural resources and eutrophication potential showed much higher values. Lower values for the algae cofiring scenario, when compared to the more » burning scenario, were observed for greenhouse potential and air acidification potential. Carbon monoxide, hydrocarbons emissions were statistically unchanged.
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The LCA results demonstrated lower net values for the algae cofiring scenario for the following using the direct injection process (in which the flue gas is directly transported to the algae ponds): SOx, NOx, particulates, carbon dioxide, methane, and fossil energy consumption. This life cycle assessment (LCA) compared the environmental impacts of electricity production via coal firing versus coal/algae cofiring. Power-plant flue gas can serve as a source of CO for microalgae cultivation, and the algae can be cofired with coal.