Sugarcane (Saccharum officinarum L.) is a perennial grass cropped in tropical and subtropical zones from Spain to South Africa. The origin of sugarcane is in the South Pacific islands and New Guinea. The main feature of sugarcane is that a sucrose-enriched juice is formed and accumulated in its stalk. This juice is extracted and used for sugar production. For its growth, sugarcane requires a moist and warm climate alternating with dry seasons. It grows better in plain or slightly sloping lands with alluvial or clay soil with abundant luminosity. Nevertheless, sugarcane grows in any soil of good quality provided there is appropriate humid­ity. This crop is grown at 16 to 29.9°C and with a pH of 4.3 to 8.4 in soils with annual precipitations of 47 to 429 mm. Cane tolerates flooding (Duke, 1998). Sugarcane is cut every 12 months on average, although the range goes from 6 to 24 months. One plantation can last up to five years.

Sugarcane is one of the most important crops in the world and plays a crucial role in the economies of many developing and emerging countries. Brazil is the major sugarcane producer followed by China and India (FAO, 2008; Table 3.1). Brazil fielded about 5.14 million ha in 2007, while China fielded 3.55 million. Among main cane producers, Colombia has the highest yields achieving on aver­age 88.89 ton/ha (FAO, 2008). If considering only the cane intended for sugar and ethanol production, the Colombian cane yield reaches more than 122 ton/ha (Asocana, 2006; Espinal et al., 2005b). In some developing countries, sugarcane is cultivated by many rural communities for producing noncentrifugal sugar (solid brown sugar), a low-cost sweetener with significant content of minerals and traces of vitamins, widely used by the populace in those countries. This product is known as gur in India or panela in Colombia. In particular, the Colombian government is encouraging the use of the cane varieties normally employed for panela produc­tion (generally, low-yield varieties) in order to utilize them for fuel ethanol produc­tion. In this way, these communities can improve their socioeconomic conditions.

TABLE 3.2

Average Sugarcane Composition

The content of sucrose, glucose, and fructose in sugarcane is significant. Process microorganisms to synthesize ethanol assimilate these sugars. Besides these carbohydrates, cane contains fiber (mainly cellulose, hemicellulose, and lignin), proteins, fats, ash, and small amounts of other substances, such as other nonfermentable sugars (e. g., raffinose), organic acids, and other reducing com­pounds. The composition of sugarcane depends on the conditions under which it was cultivated. In particular, there are great variations in the content of mois­ture, sugars, and ash. The composition of feedstocks is very important during the simulation of ethanol production processes. As process simulation is a funda­mental tool during process synthesis, the suitable specification of cane compo­nents directly influences the quality of obtained results. As an example of such specification, average percentages (by mass) of the cane constituents are shown in Table 3.2. The data were taken from information corresponding to cane varieties from Brazil, Venezuela, Colombia, and Cuba (Andrade et al., 2004; Gonzalez and Gonzalez, 2004; Sanchez and Cardona, 2008a; Suarez and Morin, 2005).