(66c) Techno-Economic Analysis of Direct Coal-Biomass to Liquids (CBTL) Plants with Shale Gas Utilization and CO2 Capture and Storage (CCS)

Direct coal liquefaction (DCL) technology is a promising technology for producing transportation fuels from non-petroleum sources. However, a large amount of H₂ is required in the DCL system because of the low H/C ratio in coal. A recent study shows that about 0.48 tonne of CO₂ is released per barrel of transportation fuels produced in the Shenhua DCL plant, where about 80% of CO₂ is produced in the gasification-based H₂ production unit. Addition of biomass and applying carbon capture and storage (CCS) technologies are two possible solutions to reduce the carbon footprint, but would lead to higher capital and operating costs. Furthermore, H₂ can also been produced from shale gas instead of coal with less capital investment and CO₂ emission, as shale gas is currently abundant in most of the continental US. Even though co-processing of coal and biomass and inclusion of CCS have been widely studied for indirect liquefaction and power generation system, limited studies have been conducted for direct liquefaction processes. With this motivation, we will present a techno-economic study of direct coal-biomass to liquid (CBTL) plants with shale gas utilization and CCS.

In this study, the direct CBTL plants is designed based on the catalytic two-stage liquefaction process investigated by HTI, where inline hydrotreating is considered.¹ Four different plant configurations, named SMR_CCS, SMR_VT, CG_CCS, CG_VT, are considered in this work based on different extent of CCS and H₂ sources. In the SMR_CCS and SMR_VT processes, hydrogen is produced from shale gas steam methane reforming (SMR) and partial oxidation of liquefaction residue. In the CG_CCS and CG_VT processes, hydrogen is produced from co-gasification (CG) of coal/biomass/residue. High extent of CCS is considered in the SMR_CCS and CG_CCS processes, while all CO₂ is vented (VT) in the SMR_VT and CG_VT processes. Both chemical and physical absorption processes are considered for carbon capture depending on the sources and partial pressure of CO₂ in the CO₂-containing stream. The process model and economic model are developed mainly in Aspen Plus^® and Aspen Process Economic Analyzer^® (APEA^®), respectively, and are validated by comparing with the data obtained from the open literature.

In this presentation, we will focus on the following aspects: (1) development of plant-wide process model and rigorous economic model in Aspen Plus^®, Aspen Exchanger Design and Rating^®, APEA^® and Excel, (2) sensitivity studies to analyze the impact of key design parameters (i.e. biomass/coal ratio, H₂ sources, extent of CCS) and investment parameters (i.e. price of coal, biomass, shale gas, project life, plant contingency and plant capacity) on key economic measures, such as net present value (NPV), internal rate of return (IRR), break-even oil price (BEOP) and equivalent oil price (EOP), (3) analysis of the potential environmental credits due to use of biomass and CCS, (4) comparison between indirect and direct CBTL plants with or without CCS.

Reference

(1) Comolli, A.G., Lee, L.K., Pradhan, V.R., Stalzer, T.H., Harris, E.C., Mountainland, D.M., Karolkiewicz, W.F. and Pablacio, R.M., Direct Liquefaction Proof-of-Concept Facility, Technical Progress Report POC Run 01, Contract No. AC22-92PC92148, Hydrocarbon Research Inc., 1995.