Environmental Impacts of Hydrogen Production Using Nuclear Energy

It is often argued that hydrogen is the transportation fuel of the future due to its high efficiency and versatility of use.  One way to obtain hydrogen is nuclear-based production using thermochemical water splitting.  Lubis et al. conducted a life cycle assessment (LCA) of this process in order to determine its environmental impacts.  The authors studied the impacts of both nuclear and copper-chlorine thermochemical plants using LCA methodology framework from the International Organization for Standardization (ISO) and CML-2001 impact categories.  The four main stages of the LCA include: i) goal definition and scope; ii) inventory analysis; iii) impact assessment; and iv) improvement assessment.  From this study it was found that the most significant environmental impacts come from the construction of the two plants and the operation of the nuclear plant.  In contrast, the operations of the thermochemical plant do not significantly contribute to the overall environmental impact.  In order to decrease the environmental impact of nuclear-based hydrogen production, the authors suggest developing more sustainable processes, particularly in the nuclear plant and construction. — Carolyn Campbell

Lubis, L.L., Dincer, I., Rosen, M.A., 2010. Life cycle assessment of hydrogen production using nuclear energy: an application based on thermochemical water splitting. Journal of Energy Resources Technology 132, 1–6.

          The authors undertook a LCA of hydrogen production using nuclear energy.  In order to minimize emissions, hydrogen is produced via a thermochemical cycle that involves a sequence of chemical reactions yielding a net reaction of splitting water.  This study analyzed the copper-chlorine (Cu-Cl) thermochemical cycle in which nuclear energy from a supercritical water-cooled reactor (SCWR) provides the thermal energy for driving the chemical reactions.  Therefore the emissions from the overall system are the sum of the advanced nuclear power plant and the thermochemical hydrogen production plant.  The nuclear plant is taken to be rated at 2060 MWth and the entire thermal output of the plant goes to producing hydrogen.  The thermochemical plant is assumed to have a hydrogen production capacity of 5200 kg/h of H2 and a 30-year operational life.  All calculations are based on 1 h of operation of the entire plant.
          Lubis et al. utilized reported literature in order to estimate the emissions of the nuclear and thermochemical plants.  It was estimated that 4.29 kg/h of uranium is needed to produce a thermal output of 2060 MWth. For the thermochemical plant the environmental impact was estimated based on the use of chemicals in the process and use of raw materials.  In order to produce 5200 kg of H2 514,800 kg of CuCl and 189,600 kg of HCl are required.  To assess the impact of hydrogen production, the environmental impacts of emitted substances were classified into environmental impact categories.  These categories include abiotic resource depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), eutrophication potential (EP), acidification potential (AP), photochemical ozone creation potential (POCP), and radioactive radiation (RAD).  The quantitative environmental impacts were then calculated by multiplying the quantity of emitted substances by the relevant classification factor and the GaBi database was utilized to determine the environmental impact of emissions based on inventory analysis. 
          The LCA produced several findings regarding the environmental impact of nuclear-based hydrogen production using thermochemical water splitting.  For GWP, the system emits 0.0025 g CO2-eq over the life of the plant, with 95% of these emissions attributable to the construction of the nuclear plant and the hydrogen plant.  Additionally, regarding the AP, the emissions of the system are 0.00015 g SO2-eq, with the 99% of emissions coming from construction and the nuclear fuel cycle.  Construction contributes significantly to other impact categories including EP, ODP, and POCP, while the nuclear fuel cycle contributes significantly to ADP and RAD.  In order to decrease the environmental effects of this system the authors suggest developing more sustainable processes in the nuclear plant and the construction of hydrogen production. 

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