Page 74 - Biofuels for a More Sustainable Future

66 Biofuels for a More Sustainable Future

Consumption, DMC), environmental pressures (e.g., CO 2 emissions), or
environmental impacts (e.g., global warming potential).
However, aiming at the decoupling may be not sufficient if the absolute
pressure generated on the environment is overcoming the earth carrying
capacity, surpassing the abovementioned planetary boundaries. Hence, eco-
nomic sustainability should aim at ensuring both economic growth and
development within the limits of the planet.
This implies evaluating not only direct cost or gains, but as well the
so-called externalities, namely, cost or benefit that affects a party who did
not choose to incur that cost or benefit (Buchanan and Stubblebine, 1962).
Besides, energy policies, including shift to new feedstock may be
vulnerable to rebound effects, namely, when the results of an intervention
stimulate a behavioral and systemic responses. Yet, the implications of
policy-induced rebounds are mostly unknown since most studies have
focused on costless and exogenous efficiency improvements that are not
linked to any specific policy intervention (Vivanco et al., 2018). The
rebound effect concept is based on the reinforcing relationship between
resource efficiency and resource use, where efficiency changes are met with
behavioral and systemic responses, such as consumer and market responses to
price changes, which result in additional demand and resource use.
Rebound effects are typically described as the benefits that are offset once
considering such additional resource use.
While the existence of rebound effects is widely accepted, there is dis-
agreement about their magnitude. Estimates range from a moderate offset-
ting of environmental gains, to a complete elimination of such gains,
depending on the boundaries, methods, scope adopted.

7 Conclusions

Sustainability science is a growing discipline, which integrates natural sci-
ence and social science to identify solutions and assess options toward a more
sustainable present and future. Regarding the role of biofuel, they have been
considered particularly controversial for what concern sustainability. Despite
being based on renewable resources, their production and consumption
could be associated with unintended burdens, requiring a systematic assess-
ment toward optimizing their production and reducing their impacts.
Among methods for impact assessment, Life cycle assessment and life
cycle-related approaches (such as social LCA) are considered particularly
promising in order to assess biofuel sustainability in a holistic manner,