This article was written by Ranjit Deshmukh.
SERC is engaged in an exciting biomass to energy project in collaboration with the Renewable and Appropriate Energy Laboratory (RAEL) group at the University of California (UC) Berkeley. SERC and RAEL are studying the feasibility of using gasification of sugarcane residue, called bagasse, for efficient cogeneration (heat and electricity) in the sugar industry. The client, Indonesian Sugar Group, wants to set up low carbon sugar mills; in other words, mills that produce the most amount of heat and electricity per quantity of fuel. Gasification combined with gas and steam turbines has the potential to be more efficient than traditional direct combustion power generation systems. By installing high efficiency power generation systems, the mills will be able to produce surplus electricity that can then be exported to the grid. In addition to earning revenues through electricity sales, the mills stand to earn more by selling carbon credits through the Clean Development Mechanism (CDM) under the Kyoto Protocol.
To help the Indonesian Sugar Group make informed decisions, SERC is taking two approaches. One is to experiment with a small-scale 20kW gasifier that has recently arrived from India. The second is to develop thermodynamic and economic models of large-scale gasification plants and learn from other existing or planned gasification projects. This is where Brazil comes into the picture. Brazil has one of the largest sugar industries in the world and an equally large biomass-to-energy program in terms of ethanol production and power generation from bagasse. Earlier in June, I had the opportunity to visit Brazil and meet with various biomass- to-energy researchers and sugar industry experts. I was accompanied by Anand Gopal, former SERC engineer and present member of RAEL. The purpose of our trip was to learn about the Brazilian experience with gasification and the latest trends in their sugar industry.
We traveled to the Brazilian state of São Paolo, which has the largest sugarcane production in Brazil and subsequently the highest number of sugar mills and biomass energy research institutions. We visited the combustion and gasification laboratories at two different campuses of the University of São Paolo as well as the University of Campinas. The Instituto de Pesquisas Tecnológicas (Institute of Technology Research) at the University of São Paolo has been conducting research in biomass gasification for the last thirty years. Most of the gasifiers being tested at these institutions were fluidized bed gasifiers, a technology most suited for bagasse gasification. The various researchers that we met gave us much insight into the intricacies of gasification and were open to future research collaboration.
Brazil was in the process of planning two large-scale gasification plants. Pilot scale tests on the atmospheric fluidized bed gasifier by the Swedish company TPS Termiska were successful. The General Electric LM2500 gas turbine was also successfully tested on low calorific gas such as the product gas from biomass gasification. Unfortunately, due to bureaucratic and financial reasons, both projects were discontinued. However, many sugar mills in Brazil are pursuing CDM projects by installing high efficiency direct combustion systems that use high pressure boilers and turbines. We visited one such mill, the Santa Elisa sugar mill. Processing six million tons of sugarcane per year, this mill is one of the largest in Brazil. After the implementation of its CDM project, the Santa Elisa sugar mill now exports 60 percent of the electricity it generates to the grid.
We learned much from our Brazilian experience and cohorts; their reports and publications offer a plethora of information. We look forward to further collaborations with our new Brazilian colleagues.