Page 309 - Biofuels for a More Sustainable Future

Key issue, challenges, and status quo of models for biofuel supply chain design 275

performance (Yue et al., 2014). The selection and design of different biomass
production activities are highly subject to the types of biomass feedstocks
given their differences in cultivation requirements (e.g., climate and soil)
and regional availability. It is noticeable that one of the preprocessing inter-
mediates, pellets, can be directly used as energy products (e.g., for combus-
tion in cogeneration heat and power plant) (Cherubini, 2010; Lam et al.,
2010). However, pellets from preprocessing were not considered as final
products in most of previous studies.
Generally, biomass feedstocks can be categorized into five types: agricul-
ture, forestry, industry (e.g., industrial waste), household (e.g., municipal
wastes), and aquaculture (Cherubini, 2010). The types of biomass feedstock
have been evolving in the past decades. The first-generation biofuel is
mostly produced from agricultural biomass, such as ethanol from corn
and sugarcane (Aden et al., 2002; Goldemberg et al., 2008), and biodiesel
from vegetable oil (Mohan et al., 2006; Ekşio glu et al., 2009). The first-
generation biofuel has been commercialized and almost 50 billion liters
are produced annually (Naik et al., 2010). The concerns related to the com-
petition with food and relatively land use change (Dutta et al., 2014) lead
to the development of the second-generation biofuel feedstocks that largely
refer to lignocellulosic biomass (Zhang et al., 2013; Cambero et al., 2016).
The common types of lignocellulosic feedstocks include by-products and
wastes from the agriculture and forest sector (e.g., corn stover, bagasse, forest
residues), wastes (e.g., municipal solid wastes), and dedicated feedstocks
(e.g., energy crops) (Sims et al., 2010). The third-generation biofuel mainly
uses algae, a feedstock that has potential advantages over previous genera-
tions of biomass feedstocks such as high lipid productivities, little competi-
tion for arable land, year-round cultivation in wastewater or sea (Moody
et al., 2014). With the advancement in metabolic engineering, the
fourth-generation focuses on producing biofuels from oxygenic photosyn-
thetic organisms (L€u et al., 2011).
The type of biomass has a large impact on the overall BSC design. It
determines the quality and quantity of biomass feedstocks at different regions
and time, affecting many decisions related to planning, scheduling, and
design of BSC. For example, preprocessing might be advantageous for bio-
mass with high moisture content to reduce transportation cost. The quality
and quantity of biomass fed into biorefinery need to be carefully investigated
to ensure the overall effectiveness of BSC (Kenney et al., 2014; Wells
et al., 2016).