(546b) Sustainable Process Decision Making With Greenscope

Authors: 
Smith, R. L., U.S. Environmental Protection Agency
Ruiz-Mercado, G. J., U.S. Environmental Protection Agency
Gonzalez, M. A., U.S. Environmental Protection Agency



The U.S. Environmental Protection Agency is developing a method and tool called GREENSCOPE (Gauging Reaction Effectiveness for the Environmental Sustainability of Chemistries with a multi-Objective Process Evaluator) to support sustainable processes.  GREENSCOPE can be used to evaluate existing processes or in the design of new ones.  With 140 indicators for objectives in four basis areas: environment, economics, energy, and efficiency, GREENSCOPE provides information on process sustainability.  Results for the various objectives show where processes are performing well and where improvements could be made. 

One of the most difficult issues of dealing with multi-objective results is determining a scientific way to incorporate the process information and user preferences.  These preferences represent the values of the decision maker, and often scientists and engineers are uncomfortable with the methods available for integrating values into objective and quantifiable science.  While the existence of values in decision making cannot be eliminated, one can navigate a path that provides scientific clarity. 

Much of the effort needed to provide clarity in decision making has already been incorporated into the GREENSCOPE methodology.  Previous work has developed absolute sustainability limits for the indicators in GREENSCOPE [1], which provides ranges that delineate worst case and target values.  Decision makers can define marginal rates of substitution (i.e., points of equal tradeoffs) between the range-bound indicators.  Inputs such as the marginal rates of substitution and GREENSCOPE indicator results provide equations that describe decision making for multi-objective process evaluations, with a strictly mathematical method solving the equations for various inputs [2].  The method will be exemplified through various results for a terephthalic acid process. 

[1] Ruiz-Mercado, G. J.; Smith, R. L.; Gonzalez, M. A., Sustainability Indicators for Chemical Processes: I. Taxonomy. Ind. & Eng. Chem. Res., 51, 2309-2328 (2012).

[2] Smith, R.L.; Ruiz-Mercado, G.J., A Method for Decision Making using Sustainability Indicators.  Submitted, Clean Tech. & Env. Policy (2012).