Page 94 - Materials Chemistry, Second Edition

80 A.-S. Nizami and I. M. Ismail

1 Introduction

1.1 Lignocellulosic Biofuels, Renewable Directive,
and Sustainability

Large-scale replacement of fossil fuels with renewable energy sources is necessary
due to energy security and climate change in the form of greenhouse gas (GHG)
emissions (Farrell et al. 2006). Thus, there is an emerging utilization of ligno-
cellulosic biomass, which is the largest source of renewable carbohydrates for
bioenergy production (Jørgensen et al. 2007). The lignocellulosic biomass is an
attractive feedstock for anaerobic digestion (AD) that produces biomethane to be
used as a biofuel. However, according to the EU renewable directive of 2009,
‘‘… the GHG emission saving from the use of biofuels and bioliquids taken into
account… shall be at least 35 %, whereas from 2017, GHG emission savings shall
be at least 50 %’’ (EC 2009). Thus, the renewable directive (EC 2009) promotes
nonfood feedstocks including perennial grasses, forest, and agricultural residues,
energy crops, organic fraction of municipal solid waste (OFMSW), and other like
substrates for biofuel production. Grasses are one of the lignocellulosic biomass
for producing enriched biomethane as a transport fuel (Peeters 2009; Eisentraut
2010; Singh et al. 2010a). Biomethane from lignocellulosic biomass has a better
energy balance when compared to first-generation liquid transport biofuels (Korres
et al. 2011). Many European countries are seeking biofuels to meet sustainability
criteria and to achieve GHG emission savings targets (Korres et al. 2010).

1.2 Significance of LCA Studies for Biofuels

The generation of biofuels is facing the challenges of becoming full commer-
cialization (Singh et al. 2010b), which is expected in near future due to improved
process technologies and value-added products (IEA 2009). Thus, to ascertain
optimal biofuel strategies, it is necessary to take into account environmental
impacts of biofuel and bioproducts (by-products) from cradle to grave. The indi-
rect input in the biofuel production process, related emissions and wastes as well
as the fate of downstream products are all included in life-cycle assessment (LCA)
studies. Thus, the overall assessment and impact evaluation of biofuels is carried
out in a systematic manner. Nevertheless, LCA can also bring inaccurate and
unsuitable actions for the industry, policy-making sectors, and people’s perception
if not exercised correctly (Korres et al. 2011).