Page 28 - Materials Chemistry, Second Edition

10 A. Bjørn et al.

2.1 Why Is LCA Important? Biofuel Case

LCA has a number of defining characteristics. Before elaborating on these char-
acteristics a real life case is presented to show how the use of LCA provided new
insights and led to major changes in policy. This is the case of first generation
biofuels used in the transport sector.
The use of biofuels is not a new trend. They were used in the form of wood and
peat before the industrialisation and were pretty much the only source of fuels then.
This changed with the emergence of cheap fossil fuels, first in the form of coal, later
followed by oil and natural gas. By the end of the twentieth-century fossil fuels had
become the dominating source for meeting the world’s primary energy demand. At
the same time the transportation sector of developed nations was responsible for an
increasing share of the total national energy demands [e.g. EC (2012)]. While
electricity and heat increasingly were supplied by other sources than fossil fuels, a
similar transition could not be observed for transportation energy (IEA 2015).
The 2000s witnessed a renewed interest in using biofuels in the transportation
sector, spurred by increasing oil prices, the question of energy security and con-
cerns over climate change. Biofuels were seen as potentially cost competitive with
gasoline and diesel and they were considered means to reduce dependencies on
large exporters of oil, many of which were (and are) located in politically unstable
regions of the world. In the early 2000s biofuels in the transportation sector were
also generally considered much better for the climate than fossil fuels. The rea-
soning was that the CO 2 emitted from the combustion of biofuels has a “neutral”
effect on climate change, because it belongs to the biogenic carbon cycle, meaning
that it used to be in the atmosphere before being taken up, via photosynthesis, by
the plants that were the sources of the biofuel and that it will be taken up by new
plants again. By contrast, CO 2 emitted from the combustion of fossil fuels origi-
nates in carbon that belongs to the much slower geological carbon cycle and can be
considered as effectively isolated from the atmosphere, because it would have
stayed in the ground for millions of years, had it not been extracted to be used as
fuel.
While the distinction between biogenic and fossil CO 2 is important, LCA studies
(Zah and Laurance 2008; Fargione et al. 2008; Searchinger et al. 2008) have shown
that it was a mistake to:
(1) consider the use of biofuels in the transport sector inherently “climate neutral”
(2) disregard potential increases in environmental problems other than climate
change from a transition from fossil fuels to biofuels.
Regarding the first point, LCA takes a life cycle perspective when evaluating
environmental impacts of a product or a system. In this case it means not only
considering the use stage of the biofuel, i.e. where its chemical energy is trans-
formed to kinetic energy in a vehicle’s combustion engine, but also considering the
industrial and agricultural processes prior to the delivery of the biofuel to the fuel
tank of the vehicle (see Fig. 2.1).