Making transportation fuels and electricity from non-petroleum-based hybrid processes: process design and optimization

This paper presents a novel energy system that produce liquid transportation fuels and electricity from hybrid feedstocks. It highlights low-rank coal (LRC) decoupling thermal conversion, char and biomass co-gasification, and LRC syncrude and Fischer-Tropsch (FT) syncrude co-refinery. Finally we propose an exergoeconomy-based life cycle optimization approach that seeks to maximize the primary exergy saving ratio (PES), primary total overnight cost saving ratio (POS), life cycle waste emissions avoidance ratio (EmA) and primary levelized cost saving ratio (LCS) by comparing their reference stand-alone sub-systems, respectively. Accordingly, the approach yields four types of optimal design decisions, namely maximum PES design, maximum POS design, maximum EmA design and maximum LCS design, among which the maximum LCS design can reflect the overall performance improvement compared to other designs. The results show that all these optimal designs produce cheap liquid fuels which are lower than $2.2/GGE (gallon of gasoline equivalent), while the LCS design can reduce breakeven oil price (BEOP) to 1.87 $/GGE under current grid electricity selling price (60$/MWh) and life cycle carbon tax (20 $/ton CO2-eq).