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BMP testingGrasses, green forage and fodder plantssingle study (5 samples)

Cereal/pea and camelina mixtures — BMP: 5 studies, weighted mean 282 m³ CH₄/t VS

Mixtures of cereals and peas with camelina are green forage or silage from extensive crops, studied as an alternative to maize. The dataset is based on a single study with several variants.

rating: goodCH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

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

Weighted mean
282m³ CH₄/t VS
Range
252–318m³ CH₄/t VS
Records
5single study (5 samples)
Publications
1source
Temperatures
37 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.2 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (carbohydrate-dominated (no protein or fat characteristics)) and the yields of compound groups according to FNR.

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 (90 m³ CH₄/t); no particular threats to stability. No additional handling requirements.

Why? Rating factors

Potential per tonne +2

  • +2potential 90 m³ CH₄/t fresh matter (BMP 282 × DM 34.5 % × VS 92.2 %)

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: low · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 5 studies

Weighted mean Individual records

BMP curves: Cereal/pea and camelina mixturesCumulative methane production over time for 5 records and the weighted mean of 282 m³ CH₄/t VS. 5 of the curves are model curves (first-order kinetics).01002003004000510152025303540time [d]m³ CH₄/t VSKaiser (2007) · 1: 252 m³ CH₄/t VS (model curve)Kaiser (2007) · 2: 270 m³ CH₄/t VS (model curve)Kaiser (2007) · 3: 279 m³ CH₄/t VS (model curve)Kaiser (2007) · 4: 293 m³ CH₄/t VS (model curve)Kaiser (2007) · 5: 318 m³ CH₄/t VS (model curve)mean282

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 (282); 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		TemperatureSampleCurve
Kaiser (2007) · 125237 °C · mesophilicMix fibers (Wheat; Camelina) silageend point (model curve)
Kaiser (2007) · 227037 °C · mesophilicMix fibers (Pea; Camelina) silageend point (model curve)
Kaiser (2007) · 327937 °C · mesophilicMix fibers (Wheat; Camelina) freshend point (model curve)
Kaiser (2007) · 429337 °C · mesophilicMix fibers (Wheat; Pea; Camelina) silageend point (model curve)
Kaiser (2007) · 531837 °C · mesophilicMix fibers (Barley; Camelina) silageend point (model curve)
Weighted mean282arithmetic mean 282, SD 25

Typical composition

Dry matter (DM)
34.5% (range 30.3–36.8)
Volatile solids (VS)
92.2 % DM (range 87.2–94.9)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 5 determinations, volatile solids: 5 determinations.

Sources: Kaiser (2007).

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
  • 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 282 m³ CH₄/t VS (median 279; range 252–318; 5 records from 1 sources).
  • Green forage and silage of cereal and pea mixtures with flax-leaved grass described in Kaiser 2007 (effect of composition on digestibility).

Drawbacks and risks

  • Spread of results in the database: standard deviation 25 at a mean of 282 m³ CH₄/t VS (5 records from 1 sources).

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

Dosing

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. Kaiser, F.L. (2007) Einfluss der stofflichen Zusammensetzung auf die Verdaulichkeit nachwachsender Rohstoffe beim anaeroben Abbau in Biogasreaktoren. Dissertation, Technische Universität München, Wissenschaftszentrum Weihenstephan
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. 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

Camelina (Camelina sativa) is an oilseed plant of the cabbage family, with modest soil requirements and a short growing season. Grown in mixtures with cereals or peas, it is the subject of research as an extensive energy crop that could compete with maize where maize cultivation is limited. The dataset includes several records from a single publication: wheat with camelina (silage and fresh matter), peas with camelina, wheat with peas and camelina, and barley with camelina, all under mesophilic conditions.

Properties relevant to digestion

The composition depends on the proportions of the species. Cereals supply carbohydrates and fibre, peas supply protein, and camelina contributes a small amount of lipids and, as a brassica, sulphur compounds. Green forage is wet and spoils quickly, so ensiling is the basic method of storage. Mixtures are sometimes easier to ensile than pure legumes if the share of cereals provides a sufficient amount of sugars. Sulphur from camelina can increase the hydrogen sulphide content of the biogas, but at typical shares of the plants in the mix the effect is usually small.

How to read the spread of results

The several records represent different combinations of species and two forms of material: fresh matter and silage, so the differences between them are not measurement noise. In real crops the result depends on the proportions of the components in the crop, the harvest date, the development stage of the cereals, moisture and the method of ensiling. Because all the records come from a single publication, they do not capture variability between laboratories and years. Differences in comminution, inoculum and substrate-to-inoculum ratio are added to this.

In biogas plant practice

Mixtures with camelina are a niche supplement to the feedstock base, of interest where soil conditions or regulations restrict maize. They are harvested as green forage or silage, shredded and ensiled like other fodder plants. The dose in the mix should take into account possible changes in sulphur and protein content, and their effect is monitored by measuring H₂S and ammonia. Yield and composition are variable, so before wider use it is worth running a BMP test on your own mixture. In addition, it is worth checking whether growing mixtures with camelina is agronomically justified on a given farm, because the green mass yield is sometimes lower than that of maize, and the choice of plant should also take crop rotation and soil protection into account.

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

  1. Kaiser, F.L. (2007). Einfluss der stofflichen Zusammensetzung auf die Verdaulichkeit nachwachsender Rohstoffe beim anaeroben Abbau in Biogasreaktoren. Dissertation, Technische Universität München, Wissenschaftszentrum Weihenstephan. https://mediatum.ub.tum.de/631394 source

All sources of the site: bibliography.

Other substrates in the group “Grasses, green forage and fodder plants”