5 INTRODUCTION Worldwide, sugarcane mills use their process biomass residues (mainly sugarcane bagasse) as fuel in cogeneration systems. In Brazil, during the harvest period the mills are electrically self- sufficient, that means that all electricity required is produced on-site from the bagasse. Since the second half of the 1980s, some mills (following a slow but consistent process) have done invest- ments aiming at the production of surplus electric- ity to be sold to the grid. It is estimated that about 20% of the Brazilian mills, most of them located in state of São Paulo, are producing and selling surplus electricity. However, the capacity of electricity produc- tion is significantly low regarding the potential taking into account the sugarcane production. Ac- cording to the Brazilian Electricity Agency – Aneel 1 – the installed capacity of electricity production from sugarcane bagasse by middle 2008 was 3.1 GW in 248 industrial units (mills). Considering that at that time there was at least 350 mills under operation, the installed capacity was more than 3.5 GW (supposing the non declared capacity in small mills), or at least 3.5% of total existing capacity of electricity production. The potential of electricity production de- pends on various factors, including the technol- 1 Agência Nacional de Energia Elétrica, in Portuguese, that is the regulatory body of the electric sector. Its data basis is available at: <www.aneel.gov.br>. POTENTIAL OF ELECTRICITY PRODUCTION FROM SUGARCANE RESIDUES Arnaldo Walter ogy of the cogeneration system (e.g., pressure and temperature of the steam raised, the use of backpressure steam turbines or extraction- condensation units etc.), the availability of bio- mass (e.g., the potential will be higher in case of sugarcane trash use), and on the number of hours of operation (e.g., only during the harvest season, or along the whole year). For instance, consider- ing that steam is raised at 82 bar, 480 ºC 2 , without reduction of the steam demand, without the use of sugarcane trash and electricity production just during the harvest period, the potential would be equal to 6 GW considering the sugarcane produc- tion in 2006 (425 Mt of sugarcane). On the other hand, considering the same steam parameters, but recovering 40% of the trash available at the field and reducing the steam demand, the potential would reach 9 GW (again supposing the operation only during the harvest period). Thus, it can be concluded that the potential is at least 2 to 3 times the installed capacity. Conversely, considering that sugarcane pro- duction can reach 730 Mt by 2012 and even sur- pass 1,000 Mt in 2017, the potential of electricity production from sugarcane bagasse could be more 2 to 3 times higher comparing to the previous evaluation. It is clear that these are very expressive figures taking into account the required necessity of enlargement of the electric system in Brazil in the following 10 to 20 years. 2 That no longer is the best technology commercially available in Brazil. Arnaldo Walter. "POTENTIAL OF ELECTRICITY PRODUCTION FROM SUGARCANE RESIDUES", p.577-582. In Luis Augusto Barbosa Cortez (Coord.). Sugarcane bioethanol — R&D for Productivity and Sustainability, São Paulo: Editora Edgard Blücher, 2014. http://dx.doi.org/10.5151/BlucherOA-Sugarcane-SUGARCANEBIOETHANOL_52