The design of chemical products and adoption of processes that are more environmentally friendly, “Green Chemistry”, has gained considerable interest in recent years. Scholars opt to describe this as the application of the twelve principles of green chemistry in the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. These principles include: waste prevention, atom economy, renewable feedstock’s, safer synthesis, safer products, atom economy, safer auxiliaries, pollution prevention, energy efficiency, renewable feedstock’s, safer synthesis, derivative reduction, catalysis, degradability, pollution prevention and accident prevention. Not only is the environmental concern discouraging the use of coal, natural gas and petroleum as the primary sources of energy, but also the increase in energy demand is inclining researchers to develop novel and current techniques that seek new energy sources.
Hydrogen is a promising future energy carrier since it is very important and environmentally friendly alternative to fossil fuels. It is also carbon free and henceforth carbon dioxide emission free. However, it can be generated from a wide array of fossil fuel and sustainable energy sources which consequently determine the type of emission that will occur. Various production methods such as: gasification, electrolysis and biological routes upon which some are not carbon dioxide free, others consume extreme chemicals, some use non-renewable resources while others have unknown life cycles are used in its production.
Researchers Dicle Celik and Meltem Yıldız at Kocaeli University in Turkey proposed a study that focused on terminating the dependency on non-renewable resources, waste reduction and increasing efficiency in hydrogen production processes and systems. Their main objective was to associate hydrogen production methods with the twelve principles of green chemistry. The purpose of their study was to determine which of the hydrogen production techniques provided the principles of green chemistry since the technique that provides the most of those principles has been deemed to be greener. Their research work is now published in International Journal of Hydrogen Energy.
Researchers begun the study of the fifteen different hydrogen production methods by grouping them into four main sub groups with respect to their input energy sources. The groups were electrical, thermal, hybrid and biological methods. The researchers then evaluated each of these techniques for the twelve principles of green chemistry.
Celik and Yıldız observed that among the electrical methods, electrolysis was a greener alternative to plasma arc dissociation. Also the comparison of the thermal methods showed that the best choice for the environment was the thermal decomposition method if only one clean energy was to be used. Such high temperatures in thermal decomposition could only be achieved using nuclear energy resources which is a contradictive topic. Therefore, biomass steam reforming or gasification could be an alternative. The two researchers also noted that among the hybrid systems, the best environmentally alternative method was the photo-electrochemical water splitting. Eventually, all biological methods were seen to be environmentally friendly since they use or mimic a natural pathway.
In an overview of the main hydrogen production processes, the work presented in their study show that water electrolysis among electrical methods, biomass gasification is carbon dioxide neutral among thermal methods, photo-electrochemical production among the hybrid methods and bio-photolysis and photo-fermentation among biological methods makes hydrogen production “green”. Therefore, in the near future, society should be able to produce hydrogen in agreement with the principles of green chemistry.
Dicle Celik, Meltem Yıldız. Investigation of hydrogen production methods in accordance with green chemistry principles. International journal of hydrogen energy, volume 42(2017) pages 23395-23401.Go To International journal of hydrogen energy