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Stichnothe et al. Carbon Footprints 2026, 5, 11 Page 7 of 17

Animal feed is usually a complex mix of different ingredients. Several studies have investigated the
replacement potential of PKM with respect to mostly soybean meal but also fishmeal, corn, and wheat
bran [48-54] . PKM can be integrated into all animal feed mixes to a certain degree, but what is substituted will
most likely depend on the local market of animal feed.

Inventory
Inventory data for oil palm production are taken from and the nutrient composition of fronds and EFB are
[31]
taken from .
[9]
The following assumptions are used for the CHP plant:

- For sake of simplicity the oil extraction rate (OER) is assumed to be 23%, although it can vary between 19%
and 26%. However, the technical improvement of OER is not within the scope of this study

- 1 t FFB processed in the palm oil mill generates 130 kg mesocarp fibers and 54.6 kg shells, the ratio between
the residues is assumed to be constant.

- The average low calorific value (LCV) of mesocarp fibers is 11 MJ kg , while the LCV of shells is 13.4 MJ
-1
kg . These values can vary, e.g. reported 16.3 MJ kg kernel nut shells and 10 MJ kg for mesocarp fibers.
[55]
-1
[56]
-1
-1
The selected LCV values are at the lower end so that electricity surplus is not overestimated.
- Heat demand is 1,100 MJ t FFB and electricity demand is 22.5 kWh t FFB .
[57]
-1
-1
- CHP efficiency in typical palm oil mills is 0.72 according to and can reach 88% in energy-optimized CHP
[57]
plants. Just the lower CHP-efficiency is used, as it represents the current situation in palm oil mills better.
The life cycle stages and related mass flows for 1 ha plantation area are shown in Figure 3.

Life cycle impact assessment
This study uses the CF as quantitative indicator. The CF is based on the Product Environmental Footprint
methodology, version 3.1. The CF measures the potential contribution of a product to global warming. It
considers all GHG emissions associated with the product throughout its life cycle—from raw material
extraction to production, use, and end-of-life. The contribution of fossil-based emissions, biogenic-based
emissions and emissions from land use change are separately shown for the oil palm plantation.

RESULTS AND DISCUSSION
Oil palm plantation
The CF of oil palm plantations is primarily driven by LUC and by biogenic methane emissions resulting
from the treatment of POME. The CF varies significantly depending on the type of land converted. The same
LUC from forest and peatland is arbitrarily assumed, although it varies between different regions of
Indonesia. Therefore, two additional calculations are conducted to show the CF when 10% LUC comes either
from forest or peatland. The CF is calculated for oil palm plantations having a yield of 20 t FFB ha ;
-1
corresponding CF results are shown in Table 1.

In the baseline scenario, 45% of CF originates from POME treatment, approx. 17.5% from N-fertilizer, 17.5%
from diesel consumption, and 10% from potassium fertilizer. The CF nearly doubles if 10% of the area is
converted from peatland or if 20% is converted from a mix of forest and peatland. Other environmental