Biohydrogen Production in a Biorefinery Using Industrial Effluents: Challenges, Opportunities and Economic Analysis

Hydrogen is one of the simplest sources of energy to produce, and one of the best alternatives to fossil fuels due to its high energy density, high combustion rate, low environmental impact, and high availability. Today, there are many routes of generation (coal, electrolysis, natural gas, heavy oils and naphtha), but very few have been promoted to the industrial level due to their competitive costs against gasoline or diesel. It has been estimated that the biohydrogen production using biomass from industrial wastes is the technology with the greatest potential for the generation of this energy vector, however, its conversion efficiency must be increased between 60 and 80% to be competitive at these levels. Numerous challenges have been recognized including that only 15% of the energy from the biomass source can be used for the biohydrogen yield, using a fermentative route. Another significant challenge is related to the capacity of microbial consortia, where there are no known natural biochemical pathways to achieve between 60 and 80% conversion efficiency, although genetic engineering could significantly contribute to achieving these values. From an economic standpoint, two strategies can be emphasized to improve the biohydrogen production using biomass, the use of free and low-cost substrates, and finding a market for a high portion of the substrates not used in conventional processes. Accordingly, technical and engineering challenges are herein revisited, as well as economic aspects that must be overcome to achieve a sustainable implementation of biohydrogen production.