Hydrogen Generation from Biorefinery Waste: Recent Advancements and Sustainability Perspectives

Abstract

The growing environmental concerns and the alarming issue of climate change are driving the focus towards biofuels. Biorefineries are producing these biofuels and just like any petroleum refinery, it also produces some waste streams. Utilization of these waste streams is also essential to ensure circular economy. Arguably, biodiesel is the most preferred and talked about biofuel. Yellow glycerol is the major by-product during biodiesel production and stoichiometrically it is 10 wt%. Yellow glycerol contains several impurities including methanol, soap, oleic acid, etc. The biodiesel companies are facing problems to dispose this huge amount of glycerol, and hence utilization of this glycerol is important. Other biorefineries producing chemicals and ethanol produce waste water streams which require proper treatment before discharge. Generation of energy from these waste water streams is a very interesting area of intervention. Both yellow glycerol and different waste water streams from biorefineries have good potential for hydrogen generation as they are good source of free carbon. Hydrogen, as it is considered as a green and clean fuel. The growing energy crisis and climate change issues have created high demand for hydrogen. For fuel cell applications also, hydrogen demand is increasing and worldwide demand of hydrogen was projected 475 billion m3 in 2013. Biorefinery waste streams have good potential for hydrogen generation and this area is comparatively less explored. Different types of work have been reported in literature but the sustainability is questionable. In this study, the recent trends and advancements in the field of hydrogen generation from different biorefinery waste streams have been discussed and the sustainability of the different processes has been analysed. The findings of the paper will pave future research directions.