Page 86 - Biofuels for a More Sustainable Future

78 Biofuels for a More Sustainable Future

commercial scale, but others are still under development or being studied.
Many promising routes are still at research stages. Fig. 4.3 presents the main
biomass conversion routes and indicates the technological development
stage of each one (Lora and Venturini, 2012).
There are several possible products and conversion processes to be con-
sidered in a biomass conversion process, as depicted in Fig. 4.3. These prod-
ucts can be obtained in integration with existing infrastructures.

4 Biochemical routes
Biochemical conversion processes have the objective of hemicellulose and
cellulose polymers fractionation into sugar molecules. Once extracted, the
sugar can be fermented by microorganisms, and as a result the desired products
are obtained. These processes are called second-generation processes (E2G),
and the extracted sugar is fermented similarly to conventional ethanol.
Lignocellulose ethanol is an alternative that enables an increase in plant
productivity for ethanol production, without the need to increase planted
area. Considering that the productivity of a sugarcane field is 80tonnes
per hectare and that an annexed distillery produces 85L of ethanol per tonne
of sugarcane, the productivity of ethanol is 6800L per hectare of sugarcane.
Considering that 1 tonne of bagasse generates 149.3L of lignocellulose eth-
anol, for each tonne of bagasse employed in this process, the productivity per
area increases approximately 2.2%, without any additional area planted
(Walter and Ensinas, 2010; BNDES, 2008; Leal et al., 2013b).
In addition, as practically all the ethanol production in the world is first
generation, E2G could contribute to minimize questions related to land
competition between crops for food production and biofuels (PETRO-
BRAS, 2013; BNDES, 2008). Cellulosic ethanol production in a biorefin-
ery would also contribute in several ways to sustainability, such as increase in
production without the need to expand cultivated area, reducing GHG
emissions and production costs, favoring higher food security and reducing
land competition. Another product that can be manufactured in biorefi-
neries is biobutanol, which has received attention from the academic field.
Due to its possibilities as fuel and industrial feedstock, biobutanol has the
potential to become a renewable chemical commodity (Ndaba et al.,
2015). Average annual butanol production growth is 4.7%, with the United
States, Europe, and China being the largest global consumers. This increase
corresponds to 2.9 million tonnes per year, and most of this alcohol is pro-
duced by petrochemical route (Mariano et al., 2014). Butanol is miscible in
several solvents such as alcohols, ketones, aldehydes, ethers, glycols, aro-
matic hydrocarbons, having very limited water miscibility. When used as