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Comment 6 for Comments for the LCFS Method 2A2B applications (lcfs2a2bcomments-ws) - 2nd Workshop.
First Name: Monica
Last Name: Hirsch
Email Address: email@example.com
Subject: Molasses and sugar cane juice
We hereby respectfully disagree with CARBs recommendation for a new pathway for Molasses Ethanol (ETHM004) with a CI of 14.93 g CO2e/MJ and we kindly offer here our points of view and questions for your consideration. The typical fermentation process to produce ethanol in a Brazilian mill in the state of São Paulo with over 35 years of operation (before Brazil’s Pro Alcool Program), consists of a mixture of sugar molasses from the sugar factory and cane juice, coming directly from the milling. We estimated that 50.5% of all ethanol produced in Brazil Center South has the same origin (molasses) and follow the same pathway (in parallel with different amounts of cane juice, depending on the sugar mill) as the analyzed in the “Molasses to ethanol” pathway from CARB. The amount of molasses used, for any mill, is easily verified through the sugar production. Note that molasses is essentially formed by fructose and glucose, which do not crystallize, unlike sucrose, abundant in cane juice and of simple crystallization. So the fermentation process to produce ethanol in several similar units in Brazil as the presented mill, actually happen from a mixture of the poor molasses from the sugar milling with sugarcane juice, never from molasses alone. The mixture of molasses and secondary sugarcane juice in the fermentation occurs mainly for three reasons: 1 - The yeast strains used typically “prefers“ also sucrose to glucose and fructose and the fermentation process is inefficient without sucrose, demanding higher fermentation vessels (higher CAPEX), slower fermentation process (higher risk of infection and loss) converging to lower fermentation rates (lower return); 2 - Since molasses coming from the sugar factory is low in total sugars (the sucrose was crystallized), assuming maximum efficiency in the sugar production of which molasses is a by-product, it is necessary to add the cane juice directly from the milling so even before the start of fermentation (BRIX adjustment) at the risk of the ineffectiveness of the fermentation process; 3 - Unlike standard distilleries in Central America and the Caribbean that operate only from molasses and often are physically and geographically separated from the unit that processes and produces sugarcane, typical plants in the state of São Paulo, Brazil are pre-1980 and although they were born only to make sugar have expanded its crushing capacity and processing along the last decades. Thus there are no known cases of plants in the state of São Paulo that produce ethanol exclusively from molasses since, even ignoring items 1 and 2 above, its sugar factories are insufficient to process all the juice immediately. Such plants can surely produce ethanol from molasses, but only a tiny fraction of the total ethanol produced in that unit. Accepting this pathway submitted, CARB is agreeing that the mill’s production mix (between sugar and ethanol) will be used to define the CI for the pathway for molasses only production but in practice it is not happened. Will you consider two pathways for the same ethanol product? We would be glad to discuss this further with CARB and present additional evidence if necessary. We hope CARB will consider this comment and revert its position on this matter.
Original File Name:
Date and Time Comment Was Submitted: 2014-01-08 10:55:15
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