Progress and challenges of green hydrogen gas production: Leveraging on the successes of biogas

The global population's rapid growth, economic expansion, and ongoing urbanization have led to a significant surge in energy demand. Green hydrogen has found new interest in most scientific discussions because it is more environmentally friendly, scalable, and has wide application. However, it has general disadvantages, such as storage, pollutants, and generation costs. This review critically examined the current challenges of hydrogen production and how it can be further scaled down to attract biogas players and admirers. Several hydrogen production technologies were critiqued in line with user-friendliness and low energy requirements during production. The concept of 'biogas to hydrogen' and 'biomass to hydrogen' could potentially reduce the cost of green hydrogen production to about 40%. However, the main challenge of this concept is the wastage of feedstock and cost-effective hydrogen separation technologies. It was also observed that, unlike the thermochemical conversion, the biological conversion has a low energy requirement, further reducing the cost of production by 15%. The review observed that the 'biomass to biohydrogen,' which is becoming cheaper, is plagued with feedstock wastage and inefficient mechanisms to expunge impurities. It was concluded that the biological water gas shift reaction is expected to attract biogas users as its technique is similar procedurally. Hence, developing countries can now participate in cheap green hydrogen.