Bagasse and cane trash
Economics and productivity
Local and international feasibility studies are assessing whether incorporating sugarcane trash into both power and ethanol generating system can increase productivity.
Australian sugar mills burn bagasse on site to generate heat and electricity.
The dry and green leaves and tops represent about one-third of the total mass for commercial sugarcane. Dry leaf trash has about double the net heat energy of bagasse and about three times that of green leaves and tops. This can be used to generate extra electricity which can be fed back into the grid for a profit.
The Clean Energy Council’s fact sheet, Using Bagasse for Bioenergy [PDF, 73 kB], notes a premium can be paid for this surplus electricity because sugar milling seasons often coincide with peak demand loads.
An extensive project in Brazil, implemented by the United Nations Development Programme, Biomass power generation: sugarcane bagasse and trash [PDF, 5.2 MB], assessed the feasibility and benefits of harvesting sugarcane trash.
A similar project, which looked at the supply chain for the sugarcane industry supply chain for the sugarcane industry was also undertaken in Australia by RIRDC.
BenefitsThe Clean Energy Council’s fact sheet outlining the benefits of bagasse [PDF, 73 kb] claims that using bagasse to generate heat and electricity at sugar mills offers many unique benefits:
- Mills are self sufficient in terms of energy they consume
- It removes the need for transporting the bagasse away
- Extra electricity produced can be fed back into the grid for a profit
- Energy from bagasse generates less greenhouse gas emissions than conventional fossil-fuel generation
- If bagasse were left to rot, it would break down and release greenhouse gases, particularly methane, which is 27 times more dangerous to the ozone than carbon dioxide
- It plays an important role in helping Australia achieve its Renewable Energy Target
Low risk/low reward
- Generating electricity using bagasse
- Harvesting cane tops immediately before the cane harvest for cattle feed
- Producing furfural as a commodity chemical from bagasse
- Producing ethanol from weak-acid hydrolysis and fermentation of bagasse
- Biodiesel production form hydrothermal liquidifcation of bagasse
- Production of pulp and ligin in a biorefinery using bagasse
Harvesting cane trash
- Green cane harvest, where all material (cane and trash) is harvested at the same time and transported to the mill
- Conventional green cane harvest, where the cane is harvested and then the trash is collected post harvest.
Transporting cane trash
Storing bagasseBagasse needs to be properly stored so that it doesn’t rot or spontaneously combust. When bagasse is left to rot, it breaks down and releases greenhouse gases, particularly methane, which is 27 times more dangerous to the ozone than carbon dioxide. Wet cellulose, which is the principal component of bagasse, ignites more easily than dry cellulose. The Queensland University of Technology is leading a project addressing the spontaneous combustion of bagasse, which is a fundamental problem of safely storing bagasse (sugar cane fibre residue) in large stockpiles. Researchers are applying a mathematical model to predict temperature and moisture profiles of large stockpiles. The model will help maximise storage capacity while minimising the risk of spontaneous combustion not only for bagasse but other biomass materials too, including woodchip, grain and composting industries. The Queensland Department of Environment and Heritage Protection provides a guideline for managing impacts from the bulk storage of bagasse [PDF, 158 kB]. The guideline helps with minimising the risk of environmental harm arising from the establishment and management of bagasse storage areas. It provides information about actions that can be taken to minimise the impact of bagasse storages off site and on the surrounding community and environment. Control measures are provided to reduce the risk of the following:
- Dust nuisances from moving bagasse
- Smoke nuisances from accidental and spontaneous combustion of bagasse stockpile
- Odour nuisances from bagasse breaking down
- Noise nuisances from machinery and trucks used to move the bagasse
- Contamination of waterways
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