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Page 18 of 26 Salmerón et al. Carbon Footprints 2026, 5, 17

of 1,500 m ·ha ·year decreases by 10% with biochar and 20% with AVS, reaching 1,050 m ·ha ·year when
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both strategies are combined. These savings are driven by improved soil water-holding capacity from
biochar [11,62,67] and reduced evapotranspiration under AVS structures [9,59] . Such combined effects are
particularly relevant in a region facing recurrent droughts and a growing prevalence of irrigated olive
systems, which now account for 40% of the total cultivated area in a crop traditionally rainfed .
[19]
Finally, regarding productivity, our results indicate a 15% increase in olive yield (from 3.80 to 4.37 t·ha )
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associated with biochar application, attributed to enhance soil fertility and nutrient retention . This
[17]
agronomic advantage was not directly captured in previous sections as results were shown on an annual
basis, but it represents a key co-benefit for farmer adoption. These site-level findings highlight the
multidimensional benefits of integrating biochar and AVS, extending beyond climate mitigation to address
soil health, water efficiency, and crop productivity. However, variability in soil conditions and management
practices warrants further research to validate these outcomes across large spatial scales.

LIMITATIONS AND FUTURE RESEARCH
This study accounts for a wide range of possible uncertainty factors stemming from biochar effects on the
soil, its production and supply chain, and differences on PV intensity per hectare. These variabilities have
been included in the Monte-Carlo analysis to investigate how they affect our results. The conclusions drawn
from the results are generally robust to these pooled uncertainties, especially for climate change and most of
the other environmental impact categories, whereas no clear conclusions can be drawn for marine
eutrophication and terrestrial acidification, potentially leading to trade-offs. This is consistent with other
LCA studies for both biochar and AVS, which show potential trade-offs between climate change mitigation
and increased impacts in other impact categories [33,51,52,82] .

The analysis includes a dynamic quantification of the benefits from electricity displacement, accounting for
progressive grid decarbonization. However, a consistent assessment of the system’s future climatic effects
should also consider technological and manufacturing improvements across the different activities, which
may reduce the absolute impacts of the AVS and biochar systems and potentially offset part of the reduced
benefits from electricity substitution. This can be particularly evident in AVS's environmental performance,
which is sensitive to the photovoltaic panel technology used. The life cycle inventory (LCI) data sourced
from ecoinvent v3.11 does not fully reflect recent technological improvements [42,83] , as it includes an efficiency
of around 13% and a climate impact of 28.62 g CO -eq kWh . In contrast, higher module efficiency,
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combined with the use of cleaner electricity grids in manufacturing and reduced material consumption (e.g.,
thinner silicon wafers), has been reported to lower the climate impact of modern technology to as low as
15 g CO -eq kWh -1[83-85] . This represents a potential 47.60% reduction in the climate change footprint of the
2
modeled AVS. As seen in Section "Other environmental impacts", these energy and resource-intensive
manufacturing processes drive an increase in other impact categories, suggesting that the trade-offs observed
in our model, in categories like freshwater eutrophication, terrestrial ecotoxicity, or particulate matter
formation, are likely overestimated. Furthermore, this reduction in embodied impacts would mitigate the
system's sensitivity to grid decarbonization. By reducing the manufacturing burden, the total environmental
impact would decrease, ensuring a better net performance even when electricity benefits are reduced.

LCA studies are subject to different assumptions regarding system boundaries and methodological choices,
which make results specific to the individual case and comparison across studies challenging [33,45,52] . In our
case, the analysis is tailored to Andalusian olive groves and a specific feedstock composition, both of which
influence biochar yield and carbon content , as well as transport distances between pyrolysis plants and
[8]
application sites. To expand the applicability of biochar, future research should explore alternative