Does lower energy usage mean lower carbon dioxide emissions? - A new perspective on the distillation process

Although fossil fuels play an important role as the primary energy source that currently cannot be replaced easily with other energy sources, their depletion and environmental impact are becoming major concerns. Improvements in energy efficiency are believed to solve both problems simultaneously. We examined the relationships between the improvement in energy efficiency, energy usage and CO₂ emissions in industry, especially in the distillation process. The energy efficiency improvement of dimethyl ether (DME) purification performed with dividing-wall column distillation (DWC) and acetic acid recovery performed with mechanical vapor recompression (MVR) were evaluated by recalculating the amount of fuel burnt and its CO₂ emission. The results showed that the paradigm of lower energy being directly proportional to lower CO₂ emissions is not entirely correct. To avoid this confusion, a tool for examining the uncommon behavior of various systems was developed.