An extended techno-economic analysis of the utilization of glycerol as an alternative feedstock for methanol production

Glycerol is a by-product of biodiesel production and may become an environmental problem. This paper investigates the utilization of glycerol as alternative feedstock for methanol production. A mathematical model of the methanol plant encompassing the steam reforming and methanol synthesis units is employed to generate data for an economic analysis involving two comparative cases: the conventional operation of the plant using only natural gas and the operation with partial substitution of the natural gas by glycerol. The results indicate that the glycerol injection can reduce the total natural gas consumption by about 11% for a given fixed methanol production. A breakeven analysis procedure is applied to determine the limit price of glycerol that makes this operation economically feasible. Based on a natural gas price of 10.13 US$/MMbtu, this analysis demonstrates that glycerol injection is feasible if its price is lower than 78.5 US$/t. Additionally, a sensitivity analysis indicates that a variation of 10% on the natural gas price causes a 26% variation on the glycerol breakeven point. The complete set of data indicates that it is possible to explore periods of glycerol low prices to reduce the operational costs of methanol plants that suffer from high natural gas prices.