Technology-environment-economy assessment of high-quality utilization routes for coke oven gas

Abstract

Coke oven gas (COG) is an important energy resource that rich in hydrogen and methane, which is conventionally used for industrial heating but is embarking on high-quality utilization routes to produce bulk energy and materials. Previous work emphasized the comparison of COG utilization with external competitors but has limited understanding of the internal competitiveness of different COG utilization routes, making it impossible to scientifically guide the high-quality utilization of COG. This study proposed a technology-environment-economy assessment framework to compare the competitiveness of six high-quality COG utilization routes called COG to electricity (COGTE), COG to methanol (COGTM), COG to hydrogen (COGTH), COG to synthetic natural gas (COGTSNG), COG to synthetic ammonia (COGTSA), and COG to olefins (COGTO). The framework employed the life cycle assessment method based on an economic functional unit to calculated individual indicators and used the entropy weight method to integrate these indicators to a comprehensive score. The results show that energy consumption, water consumption, and carbon emission are critical defects of COGTSNG, COGTM, and COGTE, respectively. Net present value rate, internal rate of return, and dynamic payback period are common but differentiated disadvantages of the five COG utilization routes other than COGTO with the current market price, which are the main factors of their weaker comprehensive competitiveness. COGTO is expected to be the most promising high-quality COG utilization route thanks to its excellent competitiveness, handsome market demand, and special policy preferences. In addition to COGTM, any of the other five COG utilization routes are likely to be most competitive when raw material and product prices fluctuate by 25%, which suggests that the investment should be tailored to local specific prices, demand, and policies.