Economic and environmental assessment of cellulosic ethanol production scenarios annexed to a typical sugar mill.

In this work different biorefinery scenarios were investigated, concerning the co-production of bioethanol and electricity from available lignocellulose at a typical sugar mill, as possible extensions to the current combustion of bagasse for steam and electricity production and burning trash on-filed. In scenario 1, the whole bagasse and brown leaves is utilized in a biorefinery and coal is burnt in the existing inefficient sugar mill boiler. Scenario 2 & 3 are assumed with a new centralized CHP unit without/with coal co-combustion, respectively. Also, through scenarios 4 & 5, the effect of water insoluble loading were studied. All scenarios provided energy for the sugarmill and the ethanol plant, with the export of surplus electricity. Economic analysis determined that scenario 1 was the most viable scenario due to less capital cost and economies-of scale. Based on Life Cycle Assessment (LCA) results, scenario 2 outperformed the other scenarios, while three scenarios showed lower contribution to environmental burdens than the current situation.

Techno-economic comparison of biojet fuel production from lignocellulose, vegetable oil and sugar cane juice.

In this study, a techno-economic comparison was performed considering three processes (thermochemical, biochemical and hybrid) for production of jet fuel from lignocellulosic biomass (2G) versus two processes from first generation (1G) feedstocks, including vegetable oil and sugar cane juice. Mass and energy balances were constructed for energy self-sufficient versions of these processes, not utilising any fossil energy sources, using ASPEN Plus® simulations. All of the investigated processes obtained base minimum jet selling prices (MJSP) that is substantially higher than the market jet fuel price (2-4 fold). The 1G process which converts vegetable oil, obtained the lowest MJSPs of $2.22/kg jet fuel while the two most promising 2G processes- the thermochemical (gasification and Fischer-Tropsch synthesis) and hybrid (gasification and biochemical upgrading) processes- reached MJSPs of $2.44/kg and $2.50/kg jet fuel, respectively. According to the economic sensitivity analysis, the feedstock cost and fixed capital investment have the most influence on the MJSP.