Potential for biohydrogen production from organic wastes with focus on sequential dark- and photofermentation: the Philippine setting

Fossil fuel remains the world’s main source of energy, but its massive use leads to the exhaustion of natural energy resources as well as climate change. With this, the interest in developing alternative energy sources has emerged globally—among these is hydrogen. Among the hydrogen production approaches, biological fermentation has been attracting global attention because of its environmental and economic merits. This process utilizes diverse feedstocks including complex organic waste materials. The Philippines has a great potential to produce hydrogen from biomass primarily because it is an agricultural country. The country is abundant in various agricultural wastes such as livestock manure, and plant residues of rice, corn, sugarcane, and coconut, as well as agro-industrial and municipal organic wastes with millions of tons generated per year. A number of studies have explored the use of technologies such as the dark fermentation (DF), photofermentation (PF), and the integration of DF and PF to utilize organic wastes for biohydrogen production. This review paper provides an overview of the organic waste scenario in the Philippines including approaches to utilize different wastes for fermentative biohydrogen production. An initial estimate conducted on the biohydrogen production suggested that the Philippines can yield 0.34–2.24 × 106 t/year from agricultural residues alone using the proposed two stage DF-PF hybrid system, with a positive net energy conversion, hence validating the possibility of establishing a biohydrogen production system from organic wastes generated in the country.