THE SUSTAINABLE PROCESS INDEX (SPI) - EVALUATING PROCESSES ACCORDING TO ENVIRONMENTAL COMPATIBILITY

Process industry needs a strategic measure that takes environmental considerations into account as a base for decisions on future projects. Emission standards alone are not sufficient for this purpose. They are based on our knowledge of the environmental risk of substances which is fragmentary and inconclusive. On top of that emission standards are susceptible to changes in societal risk assessment. Both factors are changing rapidly undermining the usefulness of these standards for strategic planning. The SPI is based on an operationalized form of the principle of sustainability. It uses only process data known at an early stage of planning and data of natural concentrations of substances (not on their presumable impact which is usually not known). The core of the SPI evaluation is the calculation of the area needed to embed a process completely into the biosphere. Low SPI values indicate processes that are competitive under sustainable conditions and that are environmentally compatible in the long-term view.