Techno-economic and life-cycle analysis of single-step catalytic conversion of bioethanol to fuel blendstocks over Ni-doped HZSM-5 zeolite catalyst

Abstract

This work presents techno-economic and life-cycle studies focusing on the catalytic transformation of ethanol into hydrocarbon fuel blendstocks. These analyses benefit from recent advancements in catalyst and process development. The consolidated alcohol dehydration and oligomerisation for ethanol-to-hydrocarbon (CADO-ETH) conversion approach, described here, achieves a single-step transformation of wet ethanol vapour into hydrocarbons and H2O using a Ni-doped HZSM-5 catalyst. Catalyst cost estimation using the CatCost model showed that commercial synthesis of Ni/HZSM-5 incurred significant processing costs, which varied greatly depending on the manufacturing scale. Hence, catalyst production using 100 % baseline scale production (BSP) and 50 % BSP requirement showed a net catalyst cost of $31.4 and $69.9/kg, respectively. Although current CADO products closely resemble petrol blendstocks, they can also be blended with gasoline fuel at low levels. There is potential for higher-level blending in the future. The operating and annualised capital costs for converting wet ethanol into fuel blendstocks were predicted to be $0.05/L at present and projected to decrease to $0.03/L in the future. This cost is comparable to the unit energy cost of synthesising anhydrous ethanol from wet ethanol, which is $0.02/L. At an oil price of 100 $/bbl, the expected minimum selling prices for the fuel blendstocks produced by CADO are similar to the prices for conventional gasoline. However, at an oil price of $60/bbl, the estimated minimum selling prices for CADO-derived blendstocks are not competitive with conventional gasoline. Nevertheless, considering existing production incentives, the projected minimum selling price for gasoline blendstock is comparable to the oil price of $60/bbl. The LCA shows that the CO2 emissions of gasoline produced from crude oil are 90.2 gCO2 e/MJ, which is 25 %, 53 % and 63 % more than the emissions of gasoline produced from corn starch, sugarcane, and cane cellulose, respectively. The results of this study indicate that the single-step CADO-ETH technology is promising for the production of renewable fuels and offers a potential pathway to reduce the carbon footprint.