title: Energy balance of biofuel production from biological conversion of crude glycerol.
abstract: 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.
authors.affiliation: INRS Eau, Terre et Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: INRS Eau, Terre et Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
authors.forename: Song
authors.initials: S
authors.lastname: Yan
authors.affiliation: INRS Eau, Terre et Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada. Electronic address: rd.tyagi@ete.inrs.ca.
authors.forename: Rajeshwar D
authors.initials: RD
authors.lastname: Tyagi
authors.affiliation: Department of Civil Engineering, University of Nebraska-Lincoln, N104 SEC PO Box 886105 Lincoln, NE 68588-6105, USA.
authors.forename: Rao Y
authors.initials: RY
authors.lastname: Surampalli
authors.affiliation: INRS Eau, Terre et Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
authors.forename: Jose R
authors.initials: JR
authors.lastname: Valéro
mesh_terms: D056804:Biofuels; D018533:Biomass; D003246:Conservation of Energy Resources; D004736:Energy-Generating Resources; D005990:Glycerol / Q000737:chemistry*; D006801:Humans; D013816:Thermodynamics
chemical_list: D056804:Biofuels; D005990:Glycerol
keywords: Biodiesel; Biogas; Crude glycerol; Energy balance; Ethanol; Hydrogen