2.1. Unfamiliarity
FLP is still an unknown method among planners and modelers. Looking a glance at common supply energy models can prove this fact. FLP has the place neither in old members of MARKAL family nor in new one i.e. TIMES model (National Center for Analysis of Energy Systems, 1979; Abilock, 1979; Tseng, 1999; Goldstein, 2001; Haurie, 2001). Also, no other energy models applied this method in their models.
Among famous energy models, PERSEUS (1990) is only model used fuzzy theory in energy planning. This model is a complementary for EFOM model that developed by IIP[Institute for Industrial Production ] in 1990 (Lehita & Pivila, 1990; Rostami, 2001). Fuzzy model used in PERSEUS has been developed to cover some of uncertain constraints and parameters in EFOM model such as pollution emission constraints or uncertain parameters of costs. In this model, fuzzy sets are used to describe uncertainties of future increase of exogenous technical and economic parameters (like energy demand) and satisfaction level of decision-makers.
Although IIP attempts to apply fuzzy sets in energy planning was so considerable, this attempt like other attempts was discontinuous. Maybe during these years, the unique hopeful event for FLP happened in the session of executive committee of ETSAP[Energy Technology Systems Analysis Program] in 2004 that approved budget for application of FLP in TIMES model. Now we should wait to see what the structure of fuzzy model of TIMES is and which features will be put in it.