1. Ph.D. Program in Bioenergy, (Unicamp, USP, Unesp), University of Campinas, Campinas 13083-896, São Paulo, Brazil
2. Institute of Economics, Center for Agricultural and Environmental Economics (NEA), University of Campinas, Campinas 13083-857, São Paulo, Brazil
3. Interior Point Methods Group—CNPq/Department of Applied Mathematics, University of Campinas, Campinas 13098-320, São Paulo, Brazil