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Case Study 6.1 – Model Application - Whole Crop Harvesting NSW Sugar Mill<br />
(SRDC 2006b)<br />
Whole sugarcane crop harvesting to maximize cogeneration requires a substantial change to the sugar value<br />
chain. A modeling approach allows the viability <strong>of</strong> options to be assessed.<br />
Trials have been conducted at Broadwater Mill to assess the effect <strong>of</strong> whole crop processing on sugar<br />
recovery and sugar quality. The NSW cane industry has focused on whole crop transfer to the mill to extend<br />
the bagasse supply used for co-generation. The results indicated trash in the cane supply is detrimental to both<br />
sugar recovery and sugar quality. These plans required major upgrades to harvesting and transport systems.<br />
To minimize capital costs plans were made to process the trash through the raw sugar factories as part <strong>of</strong> the<br />
cane supply thereby avoiding the need to install trash separation and preparation equipment. Studies by have<br />
shown that 20% <strong>of</strong> the total mass <strong>of</strong> the total mass delivered to the mill comes as trash, leaves and tops.<br />
Modelling results demonstrated the complexity <strong>of</strong> interaction and site-specific nature <strong>of</strong> factors influencing<br />
the costs and revenues associated with power generation from trash in the sugar industry. The presence or<br />
absence <strong>of</strong> an existing co-generation plant with spare capacity and the cost effectiveness <strong>of</strong> bagasse storage<br />
are key issues. Harvesting and transporting the increased volume <strong>of</strong> material produced when harvesting the<br />
whole crop are also important. The logistical problems <strong>of</strong> harvesting and transporting the additional volumes<br />
<strong>of</strong> material associated with trash were not as great as expected due to identification in the study <strong>of</strong> logistical<br />
improvements in the efficiency <strong>of</strong> harvesting and transport.<br />
Income from electricity and renewable energy certificates need to be weighed against not only the costs <strong>of</strong><br />
constructing the co-generation facility but also costs associated with loss <strong>of</strong> trash from the field , harvesting<br />
the whole crop, transporting it to the mill, separation <strong>of</strong> cane from trash and the impact <strong>of</strong> increased<br />
extraneous matter on mill performance and sugar extraction.<br />
Integrated modelling provided clarification on the circumstances when whole crop harvesting for maximising<br />
fuel for co-generation is most likely to be feasible. Consideration is currently being given to ways to increase<br />
the bulk density <strong>of</strong> whole crop cane (eg trash shredding and compaction) as well as requirements for trash<br />
separation plant to pre-process the whole cane and reduce trash processed through the mill.<br />
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