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BMP testingEnergy crops and whole-crop plants (WCS)

Rapeseed, green biomass — BMP: 4 studies, weighted mean 367 m³ CH₄/t VS

Oilseed rape as green biomass (whole plant or leaves) is biomass from catch crops and fodder crops, rich in sulphur compounds. The dataset comprises several records from different studies.

rating: goodCH₄ 66 %

Published Updated 3 min readFeedstockData Editorial Team

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

Weighted mean
367m³ CH₄/t VS
Range
330–432m³ CH₄/t VS
Records
4studies
Publications
3sources
Temperatures
35 °C, 38 °C, 40 °Cof the test

Methane in biogas

High methane content · ≈ 6.5 kWh/m³ of biogas

measured mean of 3 studies BMP, range 60.4–72 %; in a batch test the CH₄ share tends to be higher than in a plant.

How we calculate it and what the zones mean

Rating for biogas plants

good — editorial rating for biogas plantsStable, usually accepted without a fee

Potential per tonne of fresh matter: high (60 m³ CH₄/t); no particular threats to stability. No additional handling requirements.

Why? Rating factors

Potential per tonne +2

  • +2potential 60 m³ CH₄/t fresh matter (BMP 367 × DM 18.2 % × VS 90.6 %)

Process stability 0

  • 0no factors

Handling and costs 0

  • 0no factors

Total points: 2 · thresholds: ≥ 2.5 very good, ≥ 1 good, below — neutral; negative with cumulative process risk.

Editorial rating per the methodology · confidence of the rating: medium · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 4 studies

Weighted mean Individual records

BMP curves: Rapeseed, green biomassCumulative methane production over time for 4 records and the weighted mean of 367 m³ CH₄/t VS. 4 of the curves are model curves (first-order kinetics).01002003004005000510152025303540time [d]m³ CH₄/t VSPouech (b.r.): 336 m³ CH₄/t VS (model curve)Zubr (1986) · 1: 330 m³ CH₄/t VS (model curve)Zubr (1986) · 2: 334 m³ CH₄/t VS (model curve)Lallement et al. (2023): 432 m³ CH₄/t VS (model curve)mean367

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 (367); 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
SourceBMP
m³ CH₄/t VS		CH₄ in biogas
% vol., measured		TemperatureSampleCurve
Pouech (b.r.)33660.4 %40 °C · mesophilicRapeseedend point (model curve)
Zubr (1986) · 1 DOI33072.0 %35 °C · mesophilicRape · pretreatment: Silage: Air tight glass jars , fermented 30-40 days at 20 oC.end point (model curve)
Zubr (1986) · 2 DOI33469.5 %35 °C · mesophilicRapeend point (model curve)
Lallement et al. (2023) DOI432—38 °C · mesophilicRapeseedend point (model curve)
Weighted mean36765.6 %arithmetic mean 358, SD 50

Typical composition

Dry matter (DM)
18.2% (range 10.8–21.5)
Volatile solids (VS)
90.6 % DM (range 78–94)
Nitrogen
1.2 % DM
C/N ratio
42

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: CROPGEN D4, MY-D); dry matter: 3 determinations, volatile solids: 3 determinations. C/N was calculated as the ratio of C and N content (% DM) from the same source.

Sources: Pouech, P. Fruteau, H. Bewa, H.. Agricultural crops for…; Zubr (1986); Lallement et al. (2023).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

  • seasonal
  • dilutes the feed (low DM)
  • 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 database: weighted mean 367 m³ CH₄/t VS (median 335; range 330–432; 4 records from 3 sources).

Drawbacks and risks

  • Spread of results in the database: standard deviation 50 at a mean of 358 m³ CH₄/t VS (4 records from 3 sources).

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

Dosing

No source-based dose limits.

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

Practical requirements

  • Ensiling makes it possible to store seasonal biomass; properly ensiled plants (in the study maize, sorghum, forage rye, triticale) can be stored for up to a year without loss of methane production (Herrmann et al. 2011).

Sources of the process data

  1. Zubr, J. (1986) Methanogenic fermentation of fresh and ensiled plant materials. Biomass 11(3), 159–171
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. Pouech, P. Fruteau, H. Bewa, H. (None) Agricultural crops for biogas production on anaerobic digestion plants. Biomass for energy and industry 163-165
  4. Lallement, A.; Peyrelasse, C.; Lagnet, C.; Barakat, A.; Schraauwers, B.; Maunas, S.; Monlau, F. (2023) A Detailed Database of the Chemical Properties and Methane Potential of Biomasses Covering a Large Range of Common Agricultural Biogas Plant Feedstocks. Waste 1(1), 195–227
  5. Herrmann et al. (2011). Effects of ensiling, silage additives and storage period on methane formation of biogas crops. Bioresour. Technol.

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

What it is and where it comes from

Oilseed rape (Brassica napus) is the most important oil crop in Poland, grown for seed. Green oilseed rape biomass appears when it is grown as a catch crop or fodder plant, or harvested as a whole plant before ripening. It may also be waste in the form of leaves or their remnants. The dataset comprises several records from several sources: the whole plant from the CROPGEN database, records for above-ground parts from an older study, and green oilseed rape biomass from a further publication, under mesophilic conditions.

Properties relevant to digestion

Green oilseed rape biomass has a high moisture content and a moderate fibre content, and young plants are readily digestible. As a Brassicaceae plant it contains a lot of sulphur (glucosinolates), from which hydrogen sulphide is formed in the digester. This leads to poorer biogas quality, corrosion and the need for desulphurisation. The protein content is higher than in grasses, so the risk of ammonia rises at a large share. Ensiling is possible, preferably with wilting or in a mixture with plants of higher sugar content.

How to read the spread of results

The records describe different material: the whole plant, above-ground parts and green biomass, harvested at different stages. The differences also concern cultivar, sulphur and nitrogen fertilisation, harvest date, the form of the material and sample preparation. In addition, the test protocols (inoculum, S/I ratio, temperature from 35 to 40 °C) differ. The dataset is therefore of an overview character and does not describe one specific material.

In biogas plant practice

Green oilseed rape biomass is rather an occasional substrate, associated with catch crops or fodder surpluses. In the mix its share should be limited, the H₂S content of the biogas monitored, and efficient desulphurisation available. The material must be ensiled or used quickly. Care should also be taken not to confuse it with rapeseed or rapeseed cake, which have entirely different properties. The yield is worth confirming with a BMP test of your own batch. It is also worth remembering that oilseed rape grown for seed and oilseed rape as green forage are two different agronomic situations. In the first the waste is straw, in the second the whole plant with a high moisture content, so the results from the two descriptions should not be mixed in one balance.

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 = 0.085 d−1 was assumed (median of rate constants k reported in the sources and/or fitted to the mean measured curves).

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

  1. Pouech, P. Fruteau, H. Bewa, H.. Agricultural crops for biogas production on anaerobic digestion plants. Biomass for energy and industry 163-165.
  2. Zubr, J. (1986). Methanogenic fermentation of fresh and ensiled plant materials. Biomass 11(3), 159–171. DOI: 10.1016/0144-4565(86)90064-8 DOI
  3. Lallement, A.; Peyrelasse, C.; Lagnet, C.; Barakat, A.; Schraauwers, B.; Maunas, S.; Monlau, F. (2023). A Detailed Database of the Chemical Properties and Methane Potential of Biomasses Covering a Large Range of Common Agricultural Biogas Plant Feedstocks. Waste 1(1), 195–227. DOI: 10.3390/waste1010014 DOI

All sources of the site: bibliography.

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