three phases: production phase, phase of use, and phase of elimination. However,
the goal usually includes the intended application, the reasons for conducting the
study, the target audience, and the use of the results. Moreover, although the
definition of the system is more detailed in case of project or operation improvement, the flowchart of the biofuels routes is simplified to LCA when related to the
political–environmental reports (Zhang et al. 2015).
In addition, perhaps the greatest impasse of this realization is the delimitation of
the process. Although this stage is inserted in all the works analyzed, they are not
always structured with the same level of detail. They make the results restricted
when comparisons are made.
Another important question about the starting point for reducing the constraints,
the system boundary (unit operations involved), and the functional unit (calculation
basis) should be clearly defined (Prox and Curran 2017). Therefore, the LCA for
biofuels is configured from the process of obtaining the energy biomass, the process
of extraction, transport, and use, commonly measured in units of 1 kg or 1 MJ of
biofuel.
2.2 Life Cycle Inventory
The life cycle inventory (LCI) stage involves the compilation and quantification of
inputs and outputs for each process included in the system boundary. Consequently,
these inputs and outputs include the use of resources such as the release of
Fig. 1 Driving steps for life cycle assessment
6 Life Cycle Assessment of Biofuels from Microalgae
143
the goal usually includes the intended application, the reasons for conducting the
study, the target audience, and the use of the results. Moreover, although the
definition of the system is more detailed in case of project or operation improvement, the flowchart of the biofuels routes is simplified to LCA when related to the
political–environmental reports (Zhang et al. 2015).
In addition, perhaps the greatest impasse of this realization is the delimitation of
the process. Although this stage is inserted in all the works analyzed, they are not
always structured with the same level of detail. They make the results restricted
when comparisons are made.
Another important question about the starting point for reducing the constraints,
the system boundary (unit operations involved), and the functional unit (calculation
basis) should be clearly defined (Prox and Curran 2017). Therefore, the LCA for
biofuels is configured from the process of obtaining the energy biomass, the process
of extraction, transport, and use, commonly measured in units of 1 kg or 1 MJ of
biofuel.
2.2 Life Cycle Inventory
The life cycle inventory (LCI) stage involves the compilation and quantification of
inputs and outputs for each process included in the system boundary. Consequently,
these inputs and outputs include the use of resources such as the release of
Fig. 1 Driving steps for life cycle assessment
6 Life Cycle Assessment of Biofuels from Microalgae
143