Manufacturing Ethylene from Wet Shale Gas and Biomass: Comparative Technoeconomic Analysis and Environmental Life Cycle Assessment

Abstract

This paper presents comparative technoeconomic and environmental analyses of three ethylene manufacturing pathways based on ethane-rich shale gas, corn stover, and corn grain. The shalegas-based pathway includes two processing steps, namely, shale gas processing to produce ethane and ethane steam cracking to manufacture ethylene. The two biomass-based pathways also contain two processing steps each, namely, bioethanol production via fermentation and ethylene manufacturing via bioethanol dehydration. A distributed−centralized processing network that consists of distributed ethane/bioethanol production and centralized ethylene manufacturing is employed for each of the three pathways. Detailed process simulation models are developed for major processing steps, and the three pathways are then modeled on five different ethylene production scales. On the basis of the detailed mass and energy balances and life cycle inventory results, we conduct technoeconomic and life cycle analyses to systematically compare the economic and environmental performances of the three ethylene manufacturing pathways. The results indicate that the shale-gasbased pathway is the most attractive due to the lowest break even ethylene prices ($0.32/kg to $1.67/kg); however, it leads to the highest greenhouse gas emissions of about 1.4 kg CO 2 -equiv/kg ethylene. On the contrary, the corn-stover-based pathway results in the lowest greenhouse gas emissions of around −1.0 kg CO 2 -equiv/kg ethylene but the highest break even ethylene prices ($2.0/kg to $4.1/kg). Sensitivity analyses are performed to systematically investigate the influences of parameter deviations on the economic and environmental performances of the three ethylene manufacturing pathways.

Life cycle assessment of plasma-assisted ethylene production from rich-in-methane gas streams

“…The overall carbon footprint of the (natural or shale) gas-toethylene plasma-assisted process, when the purge stream is valorized and WT-generated electricity is utilized (scenario 6), is compared to the carbon footprint of the conventional ethylene production process (naphtha cracking) 17 as well as other emerging processes namely, ethylene from wet shale gas 15 and biomass 16 (before CO 2 sequestration by the feedstock). The respective comparison is depicted in Fig.…”

“…is ascribed to the high volume of chemicals used for biomass to ethanol conversion (especially when stover is utilized as the feedstock) in the rst step of the process. 16 Besides, energy demand for biomass treatment and process operation (especially when grains are utilized as the feedstock) is also an important contributor to the impact. 16 Regarding the ethylene formation from wet shale gas, about half of the emissions result from the ethylene formation process section while the rest are attributed to shale gas acquisition and processing.…”

“…16 Besides, energy demand for biomass treatment and process operation (especially when grains are utilized as the feedstock) is also an important contributor to the impact. 16 Regarding the ethylene formation from wet shale gas, about half of the emissions result from the ethylene formation process section while the rest are attributed to shale gas acquisition and processing. 15 Gas aring to satisfy the furnace energy requirements for ethylene formation majorly contributes to GHG emissions, whereas gas losses occurring during wet shale gas transportation from the extraction point to the processing station are the main source of GHG emissions attributed to gas acquisition.…”

“…In addition, advanced process design and integration 13,14 of the ethylene production process with other processes, either to boost the energy utilization efficiency or coproduce other valuable products, can further improve the overall process performance. Although producing ethylene from shale gas is proven to be economically more attractive than producing it from naphtha 15 or biomass, 16 the environmental burden is higher. As claimed by Ghanta et al, 17 the main causative factor for greenhouse gas emissions is the burning of fossil-based fuel to meet the energy requirement for the shale gas cracking in high-temperature pyrolytic furnaces.…”

Role of life-cycle externalities in the valuation of protic ionic liquids – a case study in biomass pretreatment solvents

“…In recent years, LCA has been applied to the assessment of a wide range of chemicals, enabling the identification of major hotspots and improvement opportunities. [8][9][10] Environmental performance is not the only factor that impedes the penetration of ionic liquids, as their production cost may also be high. [11][12][13] This economic barrier is mainly due to small production volumes and expensive purification procedures.…”