Exergy analysis of low and high temperature water gas shift reactor with parabolic concentrating collector

Energy is one of the building blocks of modern society. The growth of the modern society has been fueled by cheap, abundant energy resources. Since the Industrial Revolution, the world concentrated on fossil fuels to provide energy needed for running factories, transportation, electricity generation, homes and buildings. In parallel to the increase in the consumption of energy, living standards increased. High living standards of today are owed to the fossil fuels. But, the utilization of fossil fuels in different applications has caused global warming, climate change, melting of ice caps, increase in sea levels, ozone layer depletion, acid rains, and pollution. Nowadays, total worldwide environmental damage adds up to US$5 trillion a year. On the other hand, fossil fuels are not infinite. World will be out of fossil fuels in the future. Alternatives to the use of non-renewable and polluting fossil fuels have to be investigated. One such alternative is solar energy. Solar energy is the only sources from which we can use more energy than at present, without adding new thermal energy into atmosphere. It may be used in many applications, such as active and passive space heating and cooling, industrial process heating, desalination, water heating, electric generating and solar reactor as a new perspective. Parabolic trough collectors generate thermal energy using solar energy. They are the most deployed type of solar concentrators. Especially, they are very suitable for application of middle temperature solar power systems. Storing of the solar energy is not a good way using the solar energy due to entropy generation process associated with the heat transfer. Instead of that, solar energy can be used to produce hydrogen using solar reactor. Several technologies to produce hydrogen from fossil fuels have already been developed. Although hydrogen itself is clean and has zero emission, its production from fossil fuels with existing technologies is not. It also relies on fossil fuels that no one exactly knows when they will run out. Hydrogen production with renewable energies (e.g., solar, wind, etc.), therefore, can be a viable long-term, may be, an eternal solution. Among renewable energies, solar energy is cost competitive with other conventional energy generation systems in some locations, and is the fastest growing sector. The conventional energy analysis (based on the first law analysis of thermodynamics) does not give the qualitative assessment of the various losses occurring in the components. So 6