S-BEAT: A preliminary cost estimation method for the sugarcane biorefinery

In recent years, key stakeholders within the South African sugar industry have been assessing the potential to further diversify their product portfolios. The suggested route is to assess the available sugar mill streams for their potential to manufacture value-added products. In principle, a multitude of new revenue streams can be generated which will serve markets of different sizes and values. As a first stage assessment to allow for the selection of the most economically attractive product or process candidates, the Sugar Milling Research Institute NPC had developed the New Product Greenhouse (NPG) toolbox, by which the vast number of options is reduced by assessing easily accessible parameters, such as stoichiometry, capacities and market sizes. In this paper, as a second stage, the advanced Sugarcane Biorefinery Economic Analysis Toolbox (S-BEAT) is introduced, providing both a cost estimation and economic analysis at a preliminary process design stage for preselected alternatives. Targeting processes with high technology readiness levels, the order of magnitude approach is used, which is based on data of existing plants. It accepts historical data and escalates the capital investment to the current year, whilst making adjustments for differing product capacities and plant locations. It is estimated that this method has an accuracy of about +/-30% to 50%, which is considered satisfactory for a preliminary cost estimate. The cost estimates then undergo an economic analysis to determine product profitability and allow for comparison between process and product alternatives. A sensitivity analysis is also performed to quantify the inaccuracies that may be present in S-BEAT. In order to demonstrate the potential of S-BEAT, the production of high-density polyethylene (HDPE) and polylactic acid (PLA) from clear juice was investigated. The resulting economic analysis highlights the commercial attractiveness of the products as assessed by the tool.