Energy balance of biofuel production from biological conversion of crude glycerol

• Published in: Journal of environmental management 2016-04, Vol.170, p.169-176
• Main Authors: Zhang, Xiaolei, Yan, Song, Tyagi, Rajeshwar D., Surampalli, Rao Y., Valéro, Jose R.
• Format: Article
• Language: English
• Subjects: Biodiesel; Biodiesel fuels; Biofuels; Biogas; Biomass; Conservation of Energy Resources; Crude glycerol; Energy balance; Energy efficiency; Energy-Generating Resources; Ethanol; Glycerol - chemistry; Humans; Hydrogen; Thermodynamics
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2015.09.031

Crude glycerol, a by-product of biodiesel production, has gained significant attention as a carbon source for biofuel production. This study evaluated the energy balance of biodiesel, hydrogen, biogas, and ethanol production from 3.48 million L of crude glycerol (80% w/v). The conversion efficiency (energy output divided by energy invested) was 1.16, 0.22, 0.27, and 0.40 for the production of biodiesel, hydrogen, biogas, and ethanol respectively. It was found that the use of crude glycerol for biodiesel production was an energy gain process, with a positive energy balance and conversion efficiency of greater than 1. The energy balance revealed a net energy gain of 5226 GJ per 1 million kg biodiesel produced. Production of hydrogen, biogas and ethanol from crude glycerol were energy loss processes. Therefore, the conversion of crude glycerol to lipids and subsequently to biodiesel is suggested to be a better option compared to hydrogen, biogas, or ethanol production with respect to energy balance. •This study is an important part of ongoing efforts for crude glycerol management.•Energy balance of biofuel production from crude glycerol was estimated.•Crude glycerol for biodiesel production is energy balance favorable.