In this contribution, we study the extent to which 68
scenarios
for microalgae biofuels could help the heavy-duty transport sector
operate within planetary boundaries. The proposed scenarios are built
considering a range of alternative configurations based on three types
of fuel production processes (i.e., transesterification, hydrodeoxygenation,
and hydrothermal liquefaction), different carbon sources (such as
natural gas power plants and direct air capture), byproduct treatments,
and two electricity mixes. Our results reveal that microalgae biofuels
could significantly reduce the environmental and human health impacts
of the business-as-usual (fossil-based) heavy-duty transport sector.
Moreover, relative to standard biofuels that show large land-use requirements,
we find that microalgae biofuels also decrease the damage on biosphere
integrity substantially. Notably, pathways resorting to hydrodeoxygenation
of microalgae oil and direct air capture and carbon storage could
reduce the current impact induced globally on climate change by the
heavy transport by 77%, while attaining six-fold reductions in biosphere
integrity impacts, both relative to conventional biofuels.