Εvaluating regional net benefits of whole crop harvesting to maximise cogeneration

There has been substantial interest in maximising electricity cogeneration in Australia in response to Government policy that created a market for renewable energy. Cogeneration of electricity can be maximised by harvesting the whole crop, i.e. using the additional fibre in tops and trash to fuel cogeneration. However, whole crop harvesting will have complex and interacting impacts on the whole value chain; growing, harvesting, transport and milling. These impacts will be very difficult to predict a priori. We developed and applied a novel value chain modelling framework that included the main biophysical and economic aspects of the production of raw sugar and co-generated electricity to determine the biophysical feasibility and financial attractiveness of whole crop harvesting in three areas. In the model, income from electricity is weighed against not only the costs of constructing the co-generation facility, but also the costs associated with loss of trash from the field, harvesting the whole crop and transporting it to the mill, separation of trash from cane, and the impact of increased extraneous matter on sugar milling. In general, the impact of losing trash from the farming system was greater than anticipated, while the impacts in the harvesting and transport sectors were less than expected because of increased efficiency that could be achieved in these sectors and the overestimation of volumes of trash and tops used in previous analyses of the problem. The analysis thus provides a more complete understanding of the possible impacts of whole crop harvesting than previously available. It also illustrates the advantages of taking a comprehensive modelling approach to assess changes to the whole value chain.