IEA Bioenergy - techno-economic assessments for bioenergy applications, Task 35: PUUT16

Bagasse residues, produced from sugarcane processing, are the largest industrial biomass residues worldwide. Co-generation of heat and power is currently the only commercial large-scale use of this biomass waste. The Rankine power plant, which is the industrial technology, has a low power-to-heat ratio. Increasing the ratio would be desirable, as this would potentially lead to lower cost of electricity, and a more efficient utilization of the bagasse. As part of the IEA Bioenergy, alternatives to the Rankine cycle has been studied. Alternative bagasse energy concepts were studied by considering the current sugar mill bagasse utilization and energy requirements, and integrating bagasse pyrolysis and gasification to improve the mill's energy efficiency. In both cases combined heat and power cycles using gas turbine or engine power plants were compared to the conventional Rankine cycle. Both systems are under development and offer some advantages. The gasification system has a high efficiency, and the technical uncertainties are well known. The power plant fuelled with pyrolysis liquid is flexible and easier to operate because of de-coupling power plant and solid fuel handling. This concept has considerable technical uncertainties. All power plants may be operated for periods extending beyond the typical 180 days operation of a sugar mill either by storing densified bagasse (produced during mill operating time) or pyrolysis oil. Both advanced systems have a higher efficiency and a power-to-heat ratio than the Rankine cycle. Estimated cost of electricity for cases under different operation modes are presented and compared. The study was carried out 2000 within the IEA Bioenergy Task 22, Techno-Economic Assessments for Bioenergy Applications. The aim of the work was to study the competitiveness of new biomass to electricity concepts being developed at a specific site. The case studied deals with utilization of bagasse, which is a residue from sugar mill operation. Global potential amount of bagasse is large, and converting bagasse to electricity could play an important role in reducing green house gas emissions in countries with sugar cane cultivation.