Page 68 - Biofuels for a More Sustainable Future

Triple bottom line, sustainability and sustainability assessment, an overview 61

Other challenges are present in both the inventory (Corrado et al., 2018)
and at impact assessment stage and are affecting in general the modelling of
the agricultural stage (Sala et al., 2017).
Moving from the production of the feedstock to the production biofuels,
the lack of data related to biochemical transformation and the frequent need
of defining proxy processes may reduce the discriminating power of LCA
when comparing options between chemical production processes
(Piccinno et al., 2016).

4.3 Absolute sustainability: Assessing biofuels in light
of planetary boundaries

To illustrate the complexity and multidimensionality of the earth carrying
capacity, the concept of planetary boundaries has been put forward and a
number of thresholds identified for environmental pressures such as climate
change, nutrient load, and so on (Rockstr€om et al., 2009; Steffen et al.,
2015). Several boundaries are not yet defined and pose serious challenges
in their assessment, for example, those related to chemical pollution (Sala
and Goralczyk, 2013). Over the years, studies focusing on the operationa-
lization of the planetary boundary concept within LCA have been published
(Ryberg et al., 2016; Clift et al., 2017) aiming at integrating absolute con-
siderations into LCA, overcoming the mere use of LCA for comparative
assessment. A set of factors to be used in LCA covering 16 impact categories
has been presented in Sala et al. (2019). Beyond this, another crucial chal-
lenge is related to the need of allocating the boundaries. Notwithstanding, in
theory, each human being on the earth should have the same allocation of
the boundary, the debate is open. To operationalize the planetary bound-
aries concept, there are schools of thoughts for which there is the need of
translating boundaries into and aligned with targets that are relevant at these
decision-making scales (H€ayh€ et al., 2016).
a
4.4 The nexus challenges: Assessing interplays and
interdependencies between food, energy, land, water,
and ecosystems

Biofuels pose clear challenges to sustainability assessment as they are often
related to competing use of resources which are needed for food, materials,
and energy production.
The nexus approach and assessment starts for the consideration that the
changes in the availability of water, land, and energy supply would strongly
affect production of food, including the secure access thereof, with severe