Why is ethylene production capacity considered a key indicator of a country's petrochemical industry level?

Why is ethylene production capacity considered a key indicator of a country's petrochemical industry level?
Ethylene is the foundational building block of the petrochemical industry, with a downstream industrial chain pull effect of 1:7—every ton of ethylene drives seven times the value in downstream products. China's ethylene capacity surpassed 60 million tons by end-2025, making it the world's largest producer with over 30% of global capacity. However, scale leadership does not equal technology leadership. The recent commissioning of PetroChina's 1.2 million-ton Tarim Phase II project, featuring 99% domestic equipment localization and China's first self-developed three-motor electric drive ethylene unit, marks a breakthrough in ending reliance on imported technology for large-scale crackers and downstream polyolefin equipment. This shift from scale leader to technology leader is reshaping global supply dynamics.