Sustainability assessment determines the most sustainable pathway, taking into consideration the economic, environmental, efficiency and societal aspects. Embedding exergy analysis and novel safety evaluation approach to complement the widely-accepted economic assessment and environmental impacts assessment in a decision tree evaluation framework provides a more comprehensive, yet faster methodology to compare related processes in terms of sustainability. Considering their promise to provide high material and energy conversion from natural resources, poly-generation systems are recognized as promising technologies for future chemical and power industries.
The commonly used inherent safety approach considers chemical and process safety, but does not give due emphasis to complexity of the process flow sheet. This becomes important in the case of poly-generation systems that accept multiple feeds and produce multiple products through many pathways for chemical and energy conversion. Since the simultaneous production of chemicals and electricity offers both economical viability and thermodynamic efficiency, exergy efficiency analysis is employed for thermodynamic comparison of proposed processes.
In this paper three different poly-generation systems, which use coal and natural gas as feed to produce DME and power are compared using a comprehensive sustainability assessment methodology, which takes into account the economic, environmental, societal and efficiency factors.