Page 12 - Biofuels for a More Sustainable Future

Biofuels technologies: An overview of feedstocks, processes, and technologies 5

production. However, their use has increased over time and could even
become of a higher importance in the future. Biodiesel production from
animal fats, however, has remained rather stable over time in terms of the
percentage share in the total biofuels production (Fig. 1.3).

2.1 Conventional (first generation) biofuels
The first attempts of biofuels engine operation (peanut oil engine run by
Rudolf Diesel in 1900 and vegetable oil run engines in 1930s) as well the
first industrial biofuels were based on food crops (Ziolkowska, 2018). In
the past decades, food crop application for biofuels production has increas-
ingly been criticized due to two major issues: “fuel vs. food” trade-off and
concerns about the real CO 2 reduction potential of biofuels (some biofuels
could release more carbon in their production process than sequester it in the
feedstock growth process).
Because of these urgent issues, most studies in this area focus on compe-
tition for resources resulting from crop cultivation and their application
either for food/feed or biofuels production. This trade-off situation for food,
feed, fuel, and production factors can impact producers, distributors, and the
related markets, and finally regional and national economies (Tomei and
Helliwell, 2016; Baffes, 2013; Filip et al., 2017). Most attention in the lit-
erature has been given to land resources (Rathmann et al., 2010; Harvey
and Pilgrim, 2011) and impacts of biofuels production on food market prices
(Ak e, 2017; Enciso et al., 2016; Tyner, 2013; Ajanovic, 2011).
Conventional biofuels encompass ethanol (produced from crops with
high sugar contents, e.g., corn, cereals, sugar beet/sugar cane) and biodiesel
(produced from high oleic plants, e.g., soybean, rapeseed, palm oil, animal
fats, waste oils).
In the past decades, conventional biofuels have developed into flourish-
ing fuel markets. In 2015 in the United States alone, the consumption of
ethanol in BTU energy units (1 BTU ¼ 1055 J) amounted to 1.14 quadril-
lion BTU, while biodiesel consumption totaled 0.26 quadrillion BTU. The
total capacity of ethanol consumption was estimated at 15 billion gallons (57
billion liters), while 2 billion gallons (7.6 billion liters) for biodiesel
(US EIA, 2016).
Production of conventional biofuels has varied in different parts of the
world, subject to feedstock availability. Global production of conventional
biofuels for the transport sector reached 140 billion liters (37 billion gal) in
2017 (IEA, 2018). In 2015, Brazil and the United States accounted for 70%