Environmental impact analysis of different wastes to biohydrogen, biogas and biohytane processes

Abstract

Biofuel production, especially biohydrogen, biogas and biohythane production from waste materials is a promising technology. It contributes a unique opportunity for waste minimization, renewable energy generation and recycling of nutrients. In this review, in order to understand the environmental effects of biohydrogen and biogas produced from renewable energy sources using various production technologies, many publications on the environmental effects of biofuels produced from waste materials have been examined. The aim of this review is to present an overview of the state-of-the-art of different wastes to biohydrogen or/and biogas technologies via fermentation from the perspective of life cycle analysis. Firstly, the hydrogen and biogas production pathways and the required process steps are summarized. Then, life cycle analyses (LCA) studies are discussed in terms of their environmental impacts. It is difficult to completely compare these studies with each other due to differences in functional unit, system boundaries, analysis methods, impact categories, and software. However, as a result of the evaluation, fermentation offer benefits such as reduction of CO2 emission, ozone depletion, human health, ecotoxicity and fossil depletion. Moreover, it is perceived that the integration of biohydrogen production and anaerobic digestion from organic wastes can be an attractive option to produce biohythane that has high heat efficiency and low GHG emissions instead of biohydrogen or biogas production. Energy producing strategies can be rearranged towards life-cycle philosophy helping for dissemination of renewable energy systems usage.