On an intensification factor for green chemistry and engineering: The value of an operationally simple decision-making tool in process assessment

This perspective provides the conceptual basis and potentiality of a new metric in green chemistry and engineering. Called the intensification factor (IF), as initially intended in the scenario of process intensification, it serves as a decision-making parameter that can explicitly contain as many factors as available data of interest are to be considered. These data can be both qualitative and quantitative, e.g., chemical, technical, risk, or cost, to name a few. In this context, the IF should be treated as semi-quantitative approach that complements the green metrics circumscribed to measurable elements of mass and energy performance. In short, the concept states that if the new (sustainable) alternative is superior to the existent by a factor larger than one, the alternative is a choice worth taking. Like any decision tool, subjectivity may always be an uninvited guest when dealing with IF values. Choices are usually based on available data, not necessarily the best ones. Despite such inherent pitfalls, we show through selected case studies the pluses of this otherwise operationally simple scheme, where the IF can facilitate an effective comparison between the chemical strategies used. Our main goal lies in showing how such a simple method can help others with an interest in any decision or activity involving process intensification and innovations.