Life cycle assessment of primary energy demand and greenhouse gas (GHG) emissions of four propylene production pathways in China

Abstract

Life cycle primary energy demand (PED) and greenhouse gas (GHG) emissions for the production of propylene in China (year 2013) have been carried out by considering several propylene production routes into account, such as catalytic cracking (CC), stream cracking (SC), coal-to-olefins (CTO) and coal-to-propylene (CTP), which cover the entire life cycle including: extraction and transportation of raw resources, preparation of feedstock, and production parts of propylene. The results show that the coal-based propylene pathway represents more PED and GHG emissions than the petroleum-based propylene pathway. The propylene production via CC route has the minimal PED, whereas CTO and CTP routes consume about 2.60 and 2.04 times energy of CC. Life cycle GHG emissions via four pathways are 1.60, 2.06, 12.16, 9.23 tCO2 eq/t propylene, respectively. The coal gasification process plays a dominant contribution to GHG emissions via the coal-based propylene pathway and extraction process contributed the most via petroleum-based propylene pathway, which are the key factors for reducing the GHG emissions of life cycle of propylene. Adopting rectisol process of coal gasification prove effective, which can reduce 32.39% and 26.14% life cycle GHG emissions despite increase about 3% energy. Meanwhile, it is also effective to reduce GHG emissions by enlarging scale of steam crackers.