BMP testingBy-products of the agri-food industry

Coconut meal / oil cake — BMP: 3 studies, weighted mean 296 m³ CH₄/t VS

Coconut cake (meal) is a residue from pressing copra, rich in fibre and residual fat; results from several studies are moderately consistent.

CH₄ ≈ 66 % (estimate)

Published 8 September 2023Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Ivar Leidus / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping

Weighted mean: 296m³ CH₄/t VS
Range: 262–383m³ CH₄/t VS
Records: 3studies
Publications: 2sources
Temperatures: 35 °Cof the test

Methane in biogas

≈60–69% CH₄

High methane content · ≈ 6.6 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein-rich (process classification); fat-rich (process classification)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

not rated — editorial rating for biogas plants

Not rated: no dry matter or volatile solids in the data. We calculate the rating when the dry matter and volatile solids of the material are known.

Editorial rating per the methodology

Add to the co-digestion calculator CSV data

BMP curves from 3 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (296); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

Download CSV

Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Kouas et al. (2017) DOI	262	35 °C · mesophilic	cocnut meal	end point (model curve)
Prabhudessai et al. (2013) · 1 DOI	277	—	Coconut oil cake	end point (model curve)
Prabhudessai et al. (2013) · 2 DOI	383	—	Coconut oil cake	end point (model curve)
Weighted mean	296	arithmetic mean 307, SD 66

Process properties

fibrous
fat-rich
high dry matter
protein-rich
editorial classification

Low confidence: the description is based on general characteristics of the substrate group, not on studies of this material. Treat it as a hint to be verified.

Advantages

Methane potential in the Substraty.pl BMP dataset: weighted mean 296.0 m³ CH₄/t VS (SD 66.0; 3 records, 2 sources).
Dry and well stored; fibre and residual fat (Hendriks and Zeeman 2009).

Drawbacks and risks

Residual coconut fat (lauric acid) may inhibit at a high dose (Long et al. 2012).
Protein -> ammonia.

Co-digestion — what to combine it with, what to watch out for

combines well
substrates: high alkalinity (buffer) — e.g. Cattle manure, Pig slurry, Cattle slurry, Duck slurry, Rumen and digestive tract content
Slurry supplies N and alkalinity, balancing the high C/N of the material.^[1][2]

Dosing

No source threshold.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

Practical requirements

Shred: shredding increases the surface available for degradation and speeds it up, but does not necessarily raise the final gas yield (FNR 2010, Ch. 3 “Triturado”).

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

Coconut cake (copra meal) is a by-product of pressing coconut oil from copra, that is, the dried flesh of the coconut. It arises in oil-producing countries such as the Philippines, Indonesia, India and Sri Lanka, and in Europe it is imported as a feed ingredient. There is no production in Poland, so as a biogas substrate it is practically unavailable, and the data remain comparative material for plant oil cakes.

Properties relevant to digestion

The cake contains fibre (cellulose, hemicellulose, mannans), protein, residual fat and small amounts of sugars. The lignin content is moderate. Coconut fat is rich in medium-chain acids, mainly lauric acid, which in free form and at high concentration can inhibit microorganisms, but the residual content in the cake is small. The material is dry and stores well, which eases logistics. The protein content raises the nitrogen share, so the ammonia risk is moderate at high doses.

How to read the spread of results

The dataset contains several records from several sources: coconut meal (with a mesophilic condition stated) and cake in records with no temperature given. The spread results from the pressing technology and the residual fat, the quality of the copra, comminution and sample preparation, and from the inoculum. Meal and cake may differ in oil content, which changes the result.

In biogas plant practice

Coconut cake, where available, can be added to co-digestion at a limited share, after grinding, together with slurry or silage. pH and volatile acids should be observed. Given its price as feed, it is rarely used, and its energy use makes sense mainly in producing countries, where it is a local waste. In Poland it has no practical significance.

If the coconut cake comes from a local press, its composition may change depending on the batch of copra and the pressing temperature, so before implementation it is worth running a BMP test and an analysis of dry matter and fat content.

For installations that might consider importing such a material, the economic balance is usually unfavourable, because the cake has a high value as protein-fibre feed, and the cost of sea transport and delivery to the biogas plant exceeds the gain from the additional biogas.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.091 d⁻¹ was assumed (no kinetic data for the group – the median of all available rate constants k (93 values) was used).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

All sources of the site: bibliography.