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Ecofuel feedstocks and their 2

prospects

Andrea G. Capodaglio, Silvia Bolognesi
Department of Civil Engineering and Architecture, University of Pavia, Pavia, Italy

2.1 Introduction

The global fossil fuel crisis and increasing greenhouse gas (GHG) emissions have
spurred regulations and intensified studies and process development on alternative
fuels, with the aim to meet future energy demand and satisfy present and future sus-
tainability. Estimates predicting that some fossil fuels could be depleted within the
next 50 years [1] and that severe environmental damage due to global warming, acid
rain, and urban smog could materialize, have prompted nations to target reductions of
carbon emissions by 80%, and shift toward renewable energy resources such as solar,
wind, biofuels, etc., as these are less environmentally harmful.
The term “ecofuel” or “biofuel” includes products derived from biomasses or their
subproducts: biogas, biodiesel, bioethanol, biomethanol, bioethers (Bio DME,
DiMethylEhter; bio-ETBE, EthylTerButylEther; bio-MTBE, MethylTerButylEther),
synthetic biofuels, biohydrogen, and vegetable oils. Table 2.1 summarizes the prop-
erties of some conventional fossil fuels and biofuels [4]. Considering current levels of
production, markets seem primarily focused on the first three [5]. As renewable
energy sources, biofuels—and particularly liquid biofuels—have several notable
advantages:
(1). They provide an easily stored and transportable energy source that can be used on demand.
(2). They could reduce significantly CO 2 and micro- and macro- pollutant (particulate matter,
PM) emissions, compared to fossil fuels.
(3). They could help countries differentiate energy sources, increase energy security, and create
a more stable energy market.
(4). They could develop a new economy (in fact a sort of circular economy) associated with
their cycle, from energy crop farming (or waste biomasses recovery) to production.
At the current time, important alternative energy sources such as solar and wind are
being developed. However, they are susceptible to major drawbacks, for example,
portability and use flexibility. It is very difficult to transport large quantities of elec-
tricity without using fixed infrastructure (e.g., long power lines), or relatively
inefficient and expensive batteries. Biofuels, on the contrary, are fairly easy to trans-
port, have good energy densities, and can be used in existing engines/technology with
only minor modifications. Biofuels are therefore likely to either act as a filler in the
transition from fossil fuels to other, undiscovered technologies, or to become the new
permanent source of energy for the future.

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