As with renewable energy sources, nuclear power reactors do not emit any CO2 or other pollutant gases into the atmosphere. Using off-peak periods, hydrogen could be produced by nuclear power through electrolysis, enabling a greater utilization of these plants. As mentioned earlier, higher temperatures improve both the thermodynamics and kinetics of the process: hydrogen can be generated more energy efficiently in less time. Most of the new generation IV reactors are planned to operate at much higher temperatures (700-1000 °C) than existing reactors, which operate between 300 and 400 °C . These new reactors are thus well-suited for high-temperature electrolysis of steam for hydrogen production. The direct thermal decomposition of water is impractical as it requires temperatures in excess of 2000 °C, but thermochemical water splitting into hydrogen and oxygen can be achieved efficiently at temperatures of 800-1000 °C, by using chemical cycles. Among various processes, the currently most studied is the so-called iodine-sulfur cycle, in which SO2 and iodine are added to water in an exothermic reaction to form sulfuric acid and hydrogen iodide  (Fig. 9.6). At temperatures above 350 °C, HI decomposes to hydrogen and iodine, the latter being recycled. Sulfuric
Figure 9.6 The sulfur-iodine thermochemical cycle for the production of hydrogen.
acid decomposes at temperatures in excess of 850 °C into SO2 (which is also recycled), water, and oxygen. With SO2 and iodine being continuously recycled, the only feeds to be used up in the process are water and high-temperature heat, giving the products hydrogen, oxygen, and low-grade heat. Considering its near-zero emission characteristics, nuclear power is particularly suited to the generation of hydrogen, and the development of such processes is being conducted at several locations, including the Japan Atomic Energy Research Institute (JAERI), the Oak Ridge National Laboratory, and the Commisariat a l'Energie Atomique (CEA). High temperatures generated by nuclear plants could also be used in other energy-intensive industrial applications. If used for methane steam reforming for example, the heat provided by a high-temperature nuclear reactor could significantly reduce the amount of methane required for hydrogen production and thus reduce CO2 emissions.
Eventually, heat generated in fusion reactors could also be used in hydrogen production and in high-temperature applications proposed for advanced nuclear fission reactors.
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.