Modelling and economic evaluation of CCS/PtX technologies integrated into biomass MTG plants

Abstract

This paper analyses the technical and economic feasibility of the integration of methanol to gasoline (MTG) process based biomass to Liquid (BTL) plants with Carbon Capture and Storage Technologies (CCS) and with the use of green hydrogen (PtX technology). The BtL facility proposed is based on commercial technologies and it is composed by a biomass gasification section, a methanol production section and a methanol conversion into gasoline section. In the PtX implementation, an electrolyzer is included to improve the complete conversion of CO2 to gasoline. The use of biomass falls within the goal of achieving a near-zero emission life cycle. The system configuration selected, and the plant performance are evaluated using Aspen Plus software. The plant size considered is about 1230 bbl/d of liquid fuel products, equivalent to a consumption of about 790 t/d of biomass fed to the gasification section. When MeOH is produced by using green hydrogen from renewable electrical energy, the plant produces 2706 bbl/d of gasoline. The final goal is to evaluate the environmental performance of the system and to determine the specific cost of produced liquid fuels. Results show that the CCS introduction in BtL-MTG plants has a lighter impact on plant costs and performance since CO2 capture is already included in the base plant. The PtX technology allows to completely convert the carbon dioxide to gasoline, leading to more than double fuel production and a quasi-zero-emission integrated plant design, since the CO2 specific emission for the Base Case decreases from 0.11 kgCO2 emitted/MJfuel down to 0.011 kgCO2 emitted/MJfuel for PtX implementation. Under the present conditions of CO2 allowances price of 80 $/t CO2, the analysis of the gasoline specific production cost return values equal to 129 $/bbl for Base Case which decreases to 124 $/bbl when PtX is adopted and to 99$/bbl when CCS is implemented.