Synthesis of bioethanol production processes

Diplomsko delo je narejeno s pomočjo matematičnih modelov različnih tehnologij proizvodnje bioetanola: proces suhega mletja, proces uplinjanja s sledečo katalitično sintezo in proces uplinjanja s sledečo fermentacijo. Namen diplomske naloge je ugotoviti katera tehnologija in surovina sta ekonomsko najbolj ustrezni za proizvodnjo bioetanola. Za proces suhega mletja smo izbrali štiri različne surovine: zrnje koruze, ječmena in pšenice ter sladkorno peso. Pri procesih uplinjanja smo kot surovino uporabili slamo koruze, pšenice in ječmena ter odpadni les. Za optimiranje smo uporabili procesni sintetizer MIPSYN, v katerega smo vstavili prirejene modele procesnih enot napisane z visokim programskim jezikom GAMS. Kot glavni kriterij za ekonomsko ustreznost procesa smo določili letni dobiček, kjer smo upoštevali dohodek od prodaje etanola, ter dobilek od prodaje stranskih produktov, kot so posušenega destiliranega zrnja s topninami (DDGS), bioplina, vodika in električne energije. Analizirali smo kako vpliva nihanje cen in spreminjanje kapacitete na letni dobiček. Ugotavljali smo katera tehnologija oz. kombinacija tehnologij je ustrezna z ozirom na razpoložljivost surovin v Sloveniji. Rezultati kažejo, da so vsi procesi predvsem odvisni od cene surovin in prodajne cene bioetanola. Pri procesih kjer smo lahko uporabili cenejše lignocelulozne surovine, je dobiček večji, strošek na kilogram bioetanola pa manjši. Ugotovili smo, da s procesom suhega mletja zaradi premajhnih razpoložljivosti surovin in poseganja v prehrambno verigo ni možno donosno proizvajati bioetanola.This diploma work was performed by the use of optimisation models for the production of bioethanol employing different technologies: the dry grind process, gasification with further catalytic synthesis, and gasification with syngas fermentation. The purpose of this diploma work was to determine which bioethanol production technology is the most economically viable and acceptable. We selected four different kinds of feedstock for the dry grind process: corn grain, wheat grain, barley grain, and sugar beet. Corn stover, wheat straw, barley straw, and waste wood were used for the gasification process in order to optimise the process, we used the process synthesizer MIPSYN into which we inserted modified models of process units written using the high-level programming language GAMS. The main criterion for the economic relevance of the processes was maximisation of the annual profits, where we considered the incomes from the sale of bioethanol and from the sales of byproducts such as dried distillers grain with solubles (DDGS), biogas, hydrogen and electricity. We analysed the impacts of price volatility and changing capacities on annual profits. Our investigation identified the more suitable technology or combination of technologies for use in Slovenia in regards to the availabilities of raw materials. The results showed that all processes are dependent on raw material prices and bioethanol prices. Those processes, where we can use cheaper lingo-cellulosic feedstock, are more profitable and the cost per unit of mass of bioethanol is lower. We found out when considering current prices that the dry grind process would not be profitable for the production of bioethanol due to the lack of availability of raw materials and competition with the food chain