Ley de Lenguas de 2013

1. Concerning the integration of bioethanol co-production process routes (Table 13 Part A): - A process configuration based on hemicellulose extraction for ethanol fermentation,

followed by conventional ethanol purification through atmospheric distillation, and the conversion of cellulose and lignin residue from hemicellulose extraction to heat and power, through high pressure boilers had an overall efficiency and IRR of 26% and 28%, respectively (i.e. CPE-CD-CHPSC), and was thus recommended for future investment. This Internal Rate of Return was obtained under conservative estimates of the selling prices of the export

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products, and there was no significant risk to private investment, since the probability of the IRR falling below 25% was less than 20%. A major difference between this scenario and those typically considered for ethanol integration in literature was that enzyme costs was not part of the production costs, which gave this scenario better investment potential. Thus, it can be concluded that enzyme cost is still a major economic hindrance to the conversion of cellulose to ethanol, and that avoiding this cost through ethanol production from hemicellulose alone, would provide viable investment opportunities in second generation bio-ethanol production.

- Employing advanced technologies such as multi-effect distillation and Biomass Integrated Gasification and Combined Cycles (BIGCC) in combination with ethanol production from hemicellulose (i.e. CPE-VD-BIGCC) had an overall net efficiency of 32% and an IRR of 29% and was attractive to private investors due to low financial risk. The increase in efficiency was attributed to the greater efficiency of the BIGCC technology in generating electricity from the pre-treatment residue. Thus, there will be even more promising options for ethanol co- production with electricity export at sugar mills in future with the maturation of advanced electricity generation technologies. For such technologies however, it is recommended that the efficiencies of sugar mills are improved from 0.4 tons of steam per ton of cane to below 0.35 tons, which had been shown as a foreseeable target is the future. This is recommended because the BIGCC technology was incapable of satisfying the combined steam demand of ethanol production and sugar-mill.

- Since the maximum IRR, in terms of the weighted-average capital cost, allowed for Independent Power Producers under South African legislation is 17%, it makes bioethanol production a more feasible use of sugarcane residues than the exclusive production of electricity. Without this restriction however, BIGCC-EE will obtain IRRs that are similar to bioethanol scenarios. While exclusive electricity only benefits the electricity supply, co- production benefits the energy sector by also reducing the reliance of the transportation

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fuel demand on fossil sources, which in itself is a major source of greenhouse gas reductions in South Africa.

2. Concerning the integration of synthetic fuel production routes into existing sugar mills (Table 13 Part D)

- The most cost effective configuration for producing clean compressed syngas from sugarcane residues was allothermal gasification. Though this method was 25% less efficient than autothermal systems, the overall syngas cost was 61% less. This process avoided the costs associated with oxygen production. Furthermore, the integrated process was energy self-sufficient, due to the steam and potential electrical energy generated by the combustion chamber. Thus, as the major costs in gasification-synthesis processes occur in the production of clean, compressed syngas, using allothermal technologies for gasification of biomass residues with optimised parameters is an essential step to reducing the overall costs of synthetic fuel production.

- Conventional synthesis technologies (FT-CON and MTOH-CON) that entail gas phase reactors and recycle loops for Fischer-Tropsch (FT) and methanol synthesis had efficiencies ranging from 25 to 33%, but with poor economic feasibilities, since the IRRs ranged at 8-16%, and definitely failing to provide returns on private investment. Advanced technologies (FT-AD and MTOH-AD) for FT and methanol synthesis had better technical and economic performances, since the efficiencies range at 33-38% and IRRs range from 17-21%. There is still however, no incentive for private investment since the risk of the IRRs receding below 25% was too high, especially with the FT syncrude option since the value of the syncrude product itself is too low. Furthermore, a methanol synthesis process was shown to require an additional energy source to fulfil the thermal-energy requirements of the hosting sugar mill, implying that an integrated methanol synthesis process would not have a self-sufficient energy balance even with the maximum use of the available residues. Therefore, integration

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strategies at sugar mills that considers gasification-synthesis pathways are not options that can be considered in the mid-term. These routes should be reassessed in future when the advanced methanol reactor technologies has matured and when the sugar mills themselves are more efficient, so that the production of methanol from the residues does not compromise the energy needs.

3. Comparison between synthetic fuel and biological processing routes for integration. - The highest net exporting efficiency attained by the synthesis routes is 38% while that

attained by biological routes is 32%. The synthesis routes however, had in some instances required an import of fossil energy at a rate ranging at 1-4% of the total calorific input in order to fulfil the steam demand of the mill. Regarding the bioethanol route, a

supplementary source of energy was not required, but the process made use of reagents and chemicals for the fermenting micro-organisms to grow and function. Thus, both technologies introduce minimal greenhouse gas emissions into the life cycles of the fuels, and thus, efficiency and environmental benefits would not provide a basis to differentiate these biofuel processes.

- Bioethanol processes have greater economic feasibility than synthetic fuels, as IRRs in excess of 29% could be attained, with no significant risk to private investors, whereas the IRRs for the synthetic routes were below 22%. Therefore, bioethanol routes scenarios are available for the mid-term, while bioethanol production with advanced technologies would compete with gasification-synthesis processes as technology for the latter matures.