A sustainable energy system is key for addressing the world’s environmental and social challenges. The U.S is the second largest consumer of energy, with increased energy consumption in the previous half-century. To curb energy demand, it is essential to understand the relative price...

This paper improves on the issues of extreme data points and heterogeneity found in the linear programming data envelopment analysis (DEA) by presenting a cluster-adjusted DEA model (DEA with cluster approach). This analysis, based on efficiency, determines the number of clusters via Gap...