This paper reports the feasibility analysis of co-fired combined cycles (biomass-derived gas + natural gas) based on the gasification of sugarcane residues (bagasse and trash). Performance results are based on simulation of co-fired combined cycles. Feasibility analysis is based on estimates of the capital costs and O&M costs for such cycles, taking into account current and middle term costs of BIG-CC technology (both considering scaling and learning effects). A deep reduction of the investments regarding the gasification island and auxiliaries is a key point to make BIG-CC competitive in the electricity market, and the required learning can be reached with co-fired BIG-CC systems. Besides alleviation of technical problems related to gas turbine operation with biomass-derived gas, co-fired BIG-CC units can operate with relative flexibility regarding the fuel mix. The construction of 10-15 short- to medium-size gasification islands would be enough to induce important cost reductions due to learning effects. As long as the investment on the gasification island is reduced, and depending on the price ratio of natural gas and biomass, pure BIG-CC plants could achieve a reasonable level of feasibility regarding other options of electricity production. In the short run there is no advantage for co-fired combined cycles regarding the costs of reduction of carbon dioxide emissions, but in the middle run both co-fired and pure BIG-CC power plants can be a better option than capture and storage of CO2. © 2007 Elsevier Ltd. All rights reserved.481128882896Rodrigues, M., Walter, A., Faaij, A., Co-firing of natural gas and biomass gas in biomass integrated gasification/combined cycle systems (2003) Energy, 28, pp. 1115-1131Marbe, Å., Harvey, S., Berntsson, T., Technical, environmental and economic analysis of co-firing of gasified biofuel in a natural gas combined cycle (NGCC) combined heat and power (CHP) plant (2006) Energy, 31, pp. 1614-1631Marbe, Å., Harvey, S., Opportunities for integration of biofuel gasifiers in natural-gas combined heat-and-power plants in district-heating systems (2006) Appl Energy, 83, pp. 723-748Dechamps, P.J., Pirard, N., Mathieu, P., Part-load operation of combined cycle plants with and without supplementary firing (1995) J Eng Gas Turbine Power, 117, pp. 475-483Rodrigues, M., Walter, A., Faaij, A., Performance evaluation of atmospheric biomass integrated gasifier combined cycle systems under different strategies for the use of low calorific gases (2006) Energ Convers Manage, 2. , 10.1016/j.enconman.2006.09.016Valdés, M., Rapún, J.L., Optimization of heat recovery steam generators for combined cycle gas turbine power plants (2001) Appl Therm Eng, 21, pp. 1149-1159Consonni, S., Larson, E.D., Biomass-gasifier/aeroderivative gas turbine combined cycles: Part B - performance calculations and economic assessment (1996) J Eng Gas Turbine Power, 118, pp. 516-525Faaij, A., Van Ree, R., Waldheim, L., Olsson, E., Oudhuis, A., Van Wijk, A., Gasification of biomass wastes and residues for electricity production (1997) Biomass Bioenergy, 12 (6), pp. 387-417Pfeifenberger, J.P., Hanser, P.Q., Ammann, P.R., What's in the cards for distributed resources (1998) The Energy J, , [special issue: 1-16]Gabbrielli, R., Singh, R., Economic and scenario analyses of new gas turbine combined cycles with no emissions of carbon dioxide (2005) J Eng Gas Turbine Power, 127, pp. 531-538