Sugar crop-based biorefinery for an integrated production of sugar, ethanol and other high-value products

Although the Philippines' sugar industry contributes greatly to the country's economy. It still faces major challenges in terms of competitiveness and inadequacy as brought by the full implementation of the ASEAN Free Trade (AFTA) and inability to meet the current demand for bioethanol as fuel blend (Ang, 2018). Thus, there is a need to create an alternative revenue stream for the industry and to eliminate ethanol imports, which can be achieved by developing high-value products from sugarcane, sugar and its by-products, as well as sweet sorghum, another potential sugar crop. This can be realized through the establishment of a sugar crop-based biorefinary, which is an integrated facility for sustainable processing of biomass into a spectrum of bio-based products (food, feed, chemicals and materials) and bioenergy (biofuels, power and/or heat. Thus, the lecture was done to develop a framework for the sugar crop-based biorefinery to produce high-value products suitable for Philippine sugar factories and distilleries. In this lecture, the biorefinery concept was first discussed, including its definition and elements such as feedstock, conversion processes, platforms and products. From the available literature, as well as studies that have been made at the Department of Chemical Engineering, the various products that cabe be derived from sugar crops by fermentation and conversion or recovery were described. For sugar cane, the following products can be developed from cane trash, cane juice or syrup, sucrose and mascovado: biofuels (ethanol, methane, hydrogen), bioplastics, platform chemicals, food products, compost or soil ameliorant and other important chemicals, food products, compost or soil ameliorant and other important chemicals and products (Anh, et al., 2000; Lukatijis, et al., 2018; Bonadio et al., 2018; Palisoc, 2017; Xiao et al., 2018; Vohra, et al., 2014; Vijayendra et al., 2001; Garcia et al., 2017; Khan, 1995). For sweet sorghum juice and syrup, fermentation products include biofuels (ethanol, butanol, hydrogen) as well as important chemicals such as butadiene and lactic acid, among others. For sugar manufacture by-products such as bagasse, molasses and filter cake, products like fuel, policosanol, bioplastics, bipolymer, baker's yeast, monosodium glutamate, itaconic acid, acetone, among others, can also be obtained. After describing the high value-products that can be developed from sugar crops and their byproducts, a sugarcane-based biorefinery was proposed, supplemented with a sorghum-based biorefinery. For sweet sorhum, a possible biorefinery scenario would be integrate it with an existing sugarcane-based biorefinery, and utilize the sorghum juice or syrup for bioethanol production. Biofuels Act 2006 has created a market for bioethanol characterized by demands-supply gap and big volume imports. A consisted and reliable year round supply of feedstock is a significant cost component for biorefinery. With the seasonality of sugarcane, the use of sweet sorghum as an alternate feedstock for distillery could fill the demand for feedstock since sweet sorghum is a persistent crop. Moreover, they could be handled by a traditional sugar cane harvest and processing system. Market study and life cycle analysis of the biorefinery models presented most be done to look at all the logistic problems and issues such as cultivation, harvesting, transport, pretreatment, etc. These studies might identify the more promising biorefinery platform that will maximize the production of sugar, electricity and ethanol. Results of these studies might also help the policymakers to come up with a specific policy development in the country for the integration of sugar, ethanol and electricity in a sugar based biorefinery.