Page 13 - Biofuels for a More Sustainable Future

6 Biofuels for a More Sustainable Future

of the global biofuel supply of sugarcane- and corn-based ethanol (REN21,
2016; Arau ´jo et al., 2017). Other suppliers, that is, European Union coun-
tries and Asia have entered the biofuels market in the last two decades. Bio-
fuels production in the European Union is mainly based on biodiesel from
waste, soybeans, rapeseed, and palm (Huenteler and Lee, 2015), while in the
Americas and Asia ethanol production is prevailing with the following feed-
stocks: sugarcane, corn, wheat, and cassava. In Asia, additional efforts and
investments in recent years have contributed to a growing biodiesel market
utilizing palm, soybean, rapeseed, and Jatropha feedstocks. The regional and
feedstock diversification has been recognized by several German associations
and agencies (GTZ, 2006) as potentially conducive to the formation of an
international biofuel commodities market.

2.2 Advanced biofuels
The development of advanced biofuels was propelled in response to con-
cerns related to the “fuel-food tradeoff” as well as environmental and eco-
nomic questions surrounding conventional biofuels (UN Report, 2007). By
utilizing biomass (not suitable either for food or feed purposes) and in many
cases grown on marginal lands, the problem of resource competition in
food/fuel production could potentially be mitigated to some degree. At
the same time, emerging recognitions and new knowledge about energy
value of biofuels (compared to fossil fuels) spurred questions about economic
efficiency of biofuels in general (Czekała et al., 2018). For instance, produc-
tion of cellulosic biofuel is highly energy intensive meaning that energy con-
tained in this type of biofuel is lower than the energy required for its
production (Ge and Li, 2018).
Environmental questions about advanced biofuels relate directly to CO 2
emission reduction. Many studies provided evidence that biofuels contrib-
ute to CO 2 emission reductions in the fuel burning process (Mendiara et al.,
2018; Kousoulidou and Lonza, 2016; Subramanian et al., 2018). However,
it needs to be emphasized that the exact emission reduction levels strongly
depend on the applied feedstock, with algae being acknowledged among the
leading feedstocks (Shuba and Kifle, 2018; Su et al., 2017; Savakis and Hel-
lingwerf, 2015) with carbon negative properties (Ziolkowska and Simon,
2014). However, concerns have been raised about other biomass feedstocks
(e.g., timber) pointing out that forest bioenergy is not carbon neutral due to
high CO 2 emissions released in the wood burning process (Moomaw,
2018). According to US EIA (2016), the consumption of wood/forestry