Celso Eduardo Tuna

Hydrogen Production Processes

This chapter discusses the state-of-the-art in terms of hydrogen production processes. At first, the steam reforming reactions of ethanol, biogas, and natural gas are introduced. A study on the catalysts being used in the selected reforming processes is also presented with their respective operating temperatures, feed molar ratio, and conversion rates of reagents. Afterwards, the electrolysis process and types of electrolyzers are presented with the renewable energy sources required for such, as well as the settings adopted for this type of hydrogen production processes. This chapter is concluded with the presentation of the biological hydrogen production process from green algae, with the description of the alga strain and methodology for determining the amount of hydrogen produced.

Economic Studies of Some Hydrogen Production Processes

There are more than ten methods for an economic analysis of energetic systems. Each researcher chooses their own suitable methodology. In the case of hydrogen production processes, there is the need to use a method that permits a comparison of the cost of hydrogen production considering all the processes studied in the previous chapter.

Thermodynamic Analysis of Hydrogen Production Processes

In this chapter, thermodynamic studies are conducted for determining the energy efficiencies of each type of hydrogen production process. In the case of the steam reforming processes, a physicochemical analysis was previously conducted, which was based on the concepts of Gibbs free energy, equilibrium constant, and degree of advancement. In light of pressure and temperature conditions, the energy efficiency levels of such processes are determined. In the case of hydrogen production from renewable electrolytic processes, it was based on the electrolyzer’s efficiency and the average efficiencies of wind, photovoltaic, and hydroelectric power plants. In the case of algae, it was considered the energy contained in the hydrogen being produced and the energy consumption levels during the periods of growth, adaptation, and hydrogen production.

Ecological Efficiency of Some Hydrogen Production Processes

As hydrogen production is not a clean process in its separation (from acid, methane, hydroxide, water, alcohol, etc.), there are energy requirements, thus resulting in pollutant emissions along its production process.

Technological Advancements in Biohydrogen Production and Bagasse Gasification Process in the Sugarcane Industry with Regard to Brazilian Conditions

Global warming is caused mainly by the excessive use of fossil fuels (coal, oil, diesel, gasoline, etc.) that emit millions of tons of pollutants into the environment. Besides, the fact that these fossil fuels are nonrenewable resources promotes the research in cleaner energy sources. In this chapter are presented two different technologies that could be introduced in the sugarcane industry to generate electricity and other kinds of clean fuel (producer gas and hydrogen); the case of hydrogen production by ethanol steam reforming and biomass gasification, which appear like promising technologies for energy generation in the sugarcane industry. Currently, most hydrogen is obtained from natural gas through a process known as reforming. Other technologic alternatives that may improve the supply of energy to the sugarcane industry is the use of biomass gasifiers in association with cogeneration system utilizing combined cycles to produce simultaneously electricity and heat, a technology known as Biomass Integrated Gasification/Gas Turbine Combined Cycle (BIG/GTCC). Cogeneration, has been accepted by different industries and has gained great application in the sugarcane industry, where the thermic and electric demands are favorable to use this type of energy system. The main fuel used in the process is sugarcane bagasse which is a by-product of sugar and ethanol production processes; the obtained energy is used in the form of mechanical power, electric power, and saturated steam in the processes. The surplus electricity can be sold. Technical, economical, and ecological analyses were performed for introduction of hydrogen production and BIG/GTCC in the sugarcane industry, using bagasse as fuel, in order to identify the better scenarios for electricity and heat generation. The introduction of these technologies will engender innovations in the sugarcane industry and will promote the sector development and as main results will increase electricity production with an economic and ecologic sustainable approach.