As industrialization and urbanization accelerate, global energy consumption and greenhouse gas emissions have surged dramatically, leading to rising sea levels, reduced biodiversity, and an increase in extreme weather events. These pose unprecedented threats to the environment and ecosystems, making energy conservation and carbon reduction pressing issues of global concern.

Taiwan, as a significant player in the global manufacturing industry, faces considerable environmental pressures and challenges in energy conservation and carbon reduction. This includes not only regulatory pressures from the government and export markets but also demands from customers regarding carbon emissions. It is imperative to ensure that the entire production process meets low-carbon standards to maintain the market competitiveness of products. The government is also committed to promoting the development of renewable energy and reducing greenhouse gas emissions, aiming to cut emissions to 50% of 2005 levels by 2030 and achieve net-zero emissions by 2050.

This study focuses on a case company in the petrochemical industry, which is a sector under significant scrutiny due to its environmental impact. Historically, the company's carbon emissions have frequently hovered around the government’s carbon fee threshold of 25,000 tons CO2e. Therefore, this study implemented a project aimed at improving the factory and product carbon emissions using the DMAIC methodology. In the Define step, a project team was established, project objectives were clearly defined, and tasks and activities for each phase were planned, including ISO-related verifications. During the Measure step, detailed carbon emission data for the company and its departments were collected. In the Analyze step, a fishbone diagram identified four main causes, with major energy-consuming equipment being the first target. After replacing this equipment, although annual carbon emissions decreased by 3.4%, product unit carbon emissions increased by 5.8%. Further investigation revealed that reaction conditions were the true root causes. In the Improve step, experiments and improvements were conducted in three areas of the production process. These efforts, optimized through collaboration between R&D and production department, were scaled up to full production. Finally, in the Control step, the effectiveness of these optimizations was tracked, and process systems were established to ensure long-term results.

In summary, this study successfully helped the case company achieve its set goals, reducing annual plant-wide carbon emissions by nearly 20% and product unit carbon emissions by 10.5%. Additionally, this cross-departmental collaboration integrated knowledge and experience from different professional fields, creating a comprehensive solution. The case company clarified the actual situation through this project and developed further plans and directions for future energy conservation and carbon reduction.