Page 181 - Biofuels for a More Sustainable Future

166 Biofuels for a More Sustainable Future

5 Results and discussion 194
5.1 Human health and ecosystem quality impacts 194
5.2 Net carbon dioxide emissions 196
5.3 Biocapacity 196
5.4 Economic evaluation 197
5.5 Triple I 199
5.6 Sensitivity analyses 200
5.7 Social issues 204
6 Conclusions and recommendations 206
Acknowledgment 208
References 208

1Introduction
Fossil fuel energy supply has steadily increased twofold from >5300 Mtoe in
1973 to around 11,110 Mtoe in 2014, providing >80% of total primary
energy supply for four decades, despite increasing nonfossil energy (IEA,
2016a). This domination of fossil fuel is projected to continue until 2035
(BP p.l.c., 2016). Since fossil fuels are depletable, this will lead to a massive
future burden on natural resources. Furthermore, fossil fuel combustion is
the key driver of the surge in global carbon dioxide (CO 2 ) emissions, which
reached 32 GtCO 2 in 2014 (IEA, 2016b). As carbon dioxide emissions are
the major contributor to climate change, several substitutions of fossil fuel
are of great interest to international communities regarding future energy
guarantee and environmental and human well-being protection. Vegetable
oil-derived biodiesel is considered as an ideal alternative to fossil diesel (pet-
rodiesel) in the transport sector. This type of fuel is renewable and environ-
mentally friendly, with the potential to mitigate climate change and cause
less harm to human health (Achten, 2010). However, several disadvantages
of biodiesel have also been indicated; for example, higher impacts on the
ecosystem due to fertilizer and other agricultural chemical use (Achten,
2010), land-use changes (Fargione et al., 2008), and higher net production
costs (Rajagopal and Zilberman, 2007). Due to both the pros and cons of
biodiesel production and utilization, scholars have argued about net benefits
and sustainable potential of biodiesel for years. To settle this controversy,
biodiesel systems need to be evaluated with an appropriate sustainability
assessment tool that can consider the trade-off between various positive
and negative impacts of the system.