Thermodynamic and energy analysis of glycerol low temperature steam reforming for bio-SNG

Glycerol was previously a significant source of profit for biodiesel refineries. Due to the rapid expansion of the biodiesel industry in the last decade, surplus glycerol supply has reduced the value of crude and purified glycerol. In order to expand the uses of the glycerol by-product, an onsite low temperature glycerol steam reforming (GLT-SR) process to produce a methane (CH⁴) rich gas is proposed. Conversion of glycerol would occur in a single reactor by direct methanation. The thermodynamics of glycerol reforming at temperatures below 700K were explored leading to optimum conditions for CH⁴ formation and preventing carbon formation. Both the thermodynamics and design of the plant were carried out in Aspen Plus V8.8 and led to the evaluation of the energy efficiency and the potential to displace natural gas in a soybean biodiesel refinery. The Bio-SNG could offset 24% of the natural gas embodied energy requirement or 9% of the total embodied energy for soybean biodiesel production, from farm to use. Where glycerol is a waste product, GLT-SR can contribute to waste reduction and a circular economy.