Assessment of process options for triticale fermentation to ethanol and animal feed in the Western Cape

Du Preez, Jarien (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

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.

AFRIKAANS OPSOMMING: Daar is in Suid-Afrika ‘n toenemende aanvraag na die produksie van bio-etanol in die vermenging van petrol om fossielbrandstowwe se omgewingsimpak te verminder. Korog (kleingrane) is in hierdie projek in die Wes-Kaap vir bio-etanolproduksie ondersoek. Marginale droëlande is geskik vir Korog verbouing in die Wes-Kaap. Die projek het aanvaar dat ongeveer 407 000 ton/jaar korog op hierdie lande geproduseer kan word, wat aanleiding gegee het dat ‘n produksiekapasiteit van 160 Miljoen ℓ etanol/jaar korog bio-etanol-aanleg gebou en bedryf kan word. Vir die bio-etanol-aanleg is alternatiewe proses konfigurasies, in terme van energiebalanse en ekonomiese lewensvatbaarheid, ondersoek. Hierdie ondersoek het die gewone (warm)proses, koue-hidroliseproses, warm pre-fraksioneringsproses en ‘n kombinasie van die koue en pre-fraksioneringsprosesse ingesluit. Die volgende invloede op die projek se ekonomiese volhoubaarheid is ondersoek: ‘n Steenkool teenoor biomassa brandstofbron, ‘n gekombineerde warmte en krag (GWK) aanleg en eksterne ekonomiese insette. Die warmproses word bo die koueproses verkies, aangesien dit ‘n hoër interne opbrengskoers (IOK) het (3.02% teenoor 2.40%). Die warmproses word ook bo die warm pre-fraksioneringsproses verkies, aangesien die warmproses weereens ‘n hoër IOK het. Die pre-fraksioneringsproses produseer minder GDGO (Gedroogte distilleerde graan en oplosbarestowwe) maar met ‘n hoër protein-inhoud wat dus teen ‘n hoër prys verkoop kan word. Om die pre-fraksioneringsproses winsgewend te maak moet die pre-fraksionerings GDGOverkoopprys tussen 2.5 en 4 keer hoër wees as dié van GDGO sonder pre-fraksionering. Biomassa eerder as steenkool word aangebeveel as energie brandstofbron, aangesien dit goedkoper in die Wes-Kaap is. Biomassa verminder die projek se koolstofvrystelling met 25%. Die gebruik van ‘n GWKaanleg word aanbeveel, om stoom en elektrisiteit op die perseel te vervaardig, waarna die oortollige elektrisiteit aan nabygeleë verbruikers verkoop kan word. Die kapitaalkoste verhoog met 30% as GWK gebruik word, maar die effek op IOK word teengewerk deur die verkoop van oortollige elektrisiteit. Die aanleg se winsgewendheid word hoofsaaklik deur die basiese brandstofprys (BBP) en korogprys beïnvloed. Dus moet die subsidie berekeninge dinamies wees en derhalwe maandliks hersien word na aanleiding van die BBP en korogprys variasies. Die huidige 15% ondernemingsrentabiliteit subsidie was onvoldoende, aangesien die projek se verwagte IOK van 9.7% nie onder die huidige omstandighede bereik kon word nie. ‘n Alternatiewe subsidiemeganisme moet dus ondersoek word of alternatiewelik moet daar gepoog word om ‘n aansienlike laer korogprys te bekom. Sorghum as ‘n verwysingsgraan vir ‘n korog etanolproduksie-aanleg het ‘n groot invloed op die aanleg se IOK. ‘n Korogprys wat aansienlik laer as die SAFEX B4 graan en SAFEX sorghumprys is, is noodsaaklik vir die ekonomiese lewensvatbaar van ‘n bio-etanol-aanleg. ‘n Omvattende mark analise moet dus op die korog en GDGOpryse (pryse behoort deur ‘n kontrak verseker te word) gedoen word. Daar word aanbeveel dat alle prosessse op laboratorium en proefaanlegskaal getoets moet word. Ten slotte, die warmproses met ‘n GWKaanleg wat biomassa as energie brandstofbron gebruik vir etanolproduksie word deur die projek aanbeveel.

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