Browsing by Author "Du Preez, Jarien"

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    Assessment of process options for triticale fermentation to ethanol and animal feed in the Western Cape
    (Stellenbosch : Stellenbosch University, 2016-03) Du Preez, Jarien; Gorgens, Johann F.; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.
    ENGLISH ABSTRACT: In South Africa there is a growing interest in the production of bioethanol for blending with petrol to reduce the environmental impact of fossil fuels. This project investigated the usage of triticale (small grains) for bioethanol production in the Western Cape (WC). Triticale is suitable for cultivation on marginal drylands in the WC. The project assumed that approximately 407 000 tonne/y triticale can be produced on these lands, allowing for construction and operation of a bioethanoltriticale plant with a production capacity of 160 Million ℓ ethanol/y. Alternative process configurations for such a bioethanol facility were investigated in terms of energy balances and economic viability. This assessment included the conventional (warm) process, cold-hydrolysis process, warm pre-fractionation process and a combination of the cold and pre-fractionation processes. The following influences on the project’s economic feasibly was investigated: A coal versus biomass fuel source, a combined-heat-and-power (CHP) plant option and external economic inputs. The warm process is preferred over the cold process, since it has a higher Internal Rate of Return (IRR) (3.02% versus 2.40%). The warm process is also preferred above the warm pre-fractionated process as again the warm process gives a higher IRR. The pre-fractionated process produced less Dried Distillers Grains and Solubles (DDGS) containing a higher protein content, which can be sold at a higher price. To make the pre-fractionation process more profitable, the selling price of the prefractionated DDGS should be between 2.5-4 times higher than the DDGS without prefractionation. The use of biomass as fuel source for energy rather than coal is recommended, since it is less expensive in the WC. Biomass reduces the carbon emissions of the process by 25%. The project recommended the use of a CHP plant for onsite steam and electricity production with sales of surplus electricity to nearby users. The Capital Expenditure (CAPEX) of the plant increases with 30% when using CHP, but this increase is mitigated by the selling of excess electricity. The Basic Fuel Price (BFP) and triticale price predominantly influence the plant’s profitability. Therefore, the calculations of government subsidy for plant should be dynamic, and the subsidy should be revised monthly in accordance with the BFP and triticale price variations. The current 15% Return on Assets (ROA) subsidy calculations was insufficient to achieve an expected project IRR of 9.7%, under base case conditions. Therefore, an alternative subsidy mechanism needs to be investigated, or a significantly lower triticale grain price should be sought. Using sorghum as the reference grain for a triticale ethanol production plant has a large effect on IRR. A triticale grain price significantly below SAFEX B4 wheat and SAFEX sorghum is essential for a bioethanol plant to be economically viable. Therefore, a detailed market analysis needs to be done for triticale and DDGS prices (prices should be secured by a contract). It is recommended that all processes should be tested on lab and pilot plant scale. In conclusion, this project recommends the warm process with a CHP plant using biomass as fuel for energy source for ethanol production from triticale.