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BMP testingEnergy crops and whole-crop plants (WCS)

Rye, whole crop — BMP: 8 studies, weighted mean 313 m³ CH₄/t VS

Rye as a whole crop (WCS) is green forage harvested before grain maturity, grown on poorer soils and in cooler climates. The records cover different harvest stages.

rating: goodCH₄ 63 %

Published Updated 3 min readFeedstockData Editorial Team

Photo W.carter / Wikimedia Commons, licence CC0 1.0, source file; changes: cropping

Weighted mean
313m³ CH₄/t VS
Range
140–492m³ CH₄/t VS
Records
8studies
Publications
2sources
Temperatures
35 °C, 38 °Cof the test

Methane in biogas

High methane content · ≈ 6.3 kWh/m³ of biogas

measured mean of 5 studies BMP, range 61–64 %; 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 (96 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer.

Why? Rating factors

Potential per tonne +2

  • +2potential 96 m³ CH₄/t fresh matter (BMP 313 × DM 32.9 % × VS 93.2 %)

Process stability 0

  • 0no factors

Handling and costs −0.5

  • −0.5fibres, floating layer — shredding and intensive mixing

Total points: 1.5 · 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 8 studies

Weighted mean Individual records

BMP curves: Rye, whole cropCumulative methane production over time for 8 records and the weighted mean of 313 m³ CH₄/t VS. 8 of the curves are model curves (first-order kinetics).02004006000510152025303540time [d]m³ CH₄/t VSAmon et al. (2007) · 1: 140 m³ CH₄/t VS (model curve)Amon et al. (2007) · 2: 243 m³ CH₄/t VS (model curve)Amon et al. (2007) · 3: 275 m³ CH₄/t VS (model curve)Heiermann (2002) · 1: 283 m³ CH₄/t VS (model curve)Heiermann (2002) · 2: 370 m³ CH₄/t VS (model curve)Heiermann (2002) · 3: 410 m³ CH₄/t VS (model curve)Heiermann (2002) · 4: 476 m³ CH₄/t VS (model curve)Heiermann (2002) · 5: 492 m³ CH₄/t VS (model curve)mean313

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 (313); 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
Amon et al. (2007) · 1 DOI140—38 °C · mesophilicRyeend point (model curve)
Amon et al. (2007) · 2 DOI243—38 °C · mesophilicRyeend point (model curve)
Amon et al. (2007) · 3 DOI275—38 °C · mesophilicRyeend point (model curve)
Heiermann (2002) · 128361.0 %35 °C · mesophilicRyeend point (model curve)
Heiermann (2002) · 237064.0 %35 °C · mesophilicRyeend point (model curve)
Heiermann (2002) · 341063.0 %35 °C · mesophilicRyeend point (model curve)
Heiermann (2002) · 447664.0 %35 °C · mesophilicRye · pretreatment: Silage in 1L glass vessels packed and sealed for 3 month periodend point (model curve)
Heiermann (2002) · 549264.0 %35 °C · mesophilicRye · pretreatment: Silage in 1L glass vessels packed and sealed for 3 month periodend point (model curve)
Weighted mean31363.2 %arithmetic mean 336, SD 122

Typical composition

Dry matter (DM)
32.9% (range 25–61)
Volatile solids (VS)
93.2 % DM (range 91.4–95)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: CROPGEN D4); dry matter: 5 determinations, volatile solids: 5 determinations.

Sources: Heiermann (2002).

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
  • fibrous
  • editorial classification

Advantages

  • Methane potential in the database: weighted mean 313 m³ CH₄/t VS (median 326; range 140–492; 8 records from 2 sources).

Drawbacks and risks

  • Spread of results in the database: standard deviation 122 at a mean of 336 m³ CH₄/t VS (8 records from 2 sources).

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

Dosing

No source-based dose limits.

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. Amon, T.; Amon, B.; Kryvoruchko, V.; Machmüller, A.; Hopfner-Sixt, K.; Bodiroza, V.; Hrbek, R.; Friedel, J.; Pötsch, E.; Wagentristl, H.; Schreiner, M.; Zollitsch, W. (2007) Methane production through anaerobic digestion of various energy crops grown in sustainable crop rotations. Bioresource Technology 98(17), 3204–3212
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. Heiermann, M. Plöchl, M. Linke, B. Schelle, H. (2002) Preliminary evaluation of some cereals as energy crops for biogas production. World Renewable Energy Congress VII
  4. Hendriks, A.T.W.M.; Zeeman, G. (2009) Pretreatments to enhance the digestibility of lignocellulosic biomass. Bioresource Technology
  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

Rye is a traditional cereal in Poland, grown on lighter soils. Harvested whole before grain maturity (GPS, whole crop silage), it is used to produce silage. Because rye develops early in spring, it can be harvested earlier than maize and the next crop sown after it. The compilation contains several records from several studies: from an energy crop rotation experiment and from a study covering different growth stages, at 35 and 38 °C.

Properties relevant to digestion

As rye matures, the share of starch in the grain rises, but so does that of lignified straw, while protein and readily available compounds fall. Early harvest gives better digestible material, but with a lower yield. Rye straw is long and stiff, so thorough shredding is important. Ensiling is usually possible, provided the dry matter is suitable. The C to N ratio is more favourable than in straw, but less so than in legumes, which favours co-digestion with slurry.

How to read the spread of results

The growth stage at harvest has the greatest effect, followed by the variety (population and hybrid rye), fertilisation, year and site. Particle size, the form of the material, inoculum, substrate-to-inoculum ratio and test length also have an effect. The compilation combines several series of studies, so records from one series are not independent. The result relates to a specific stage and conditions, not to the whole category.

In biogas plant practice

Rye WCS can be a supplement to maize silage, especially on farms on lighter soils. Harvesting with a forage harvester at the optimal stage, rapid compaction and tight covering limit losses. In the ration it behaves like other cereal silages. Profitability depends on the yield and costs, and the yield is worth confirming with a BMP test, recording the growth stage at mowing. It is worth remembering the timing: rye harvested for WCS matures early, which allows harvest work to be spread out in time and the equipment to be used before the maize harvest begins. This organisational argument is sometimes as important as the gas potential of the raw material itself.

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. Amon, T.; Amon, B.; Kryvoruchko, V.; Machmüller, A.; Hopfner-Sixt, K.; Bodiroza, V.; Hrbek, R.; Friedel, J.; Pötsch, E.; Wagentristl, H.; Schreiner, M.; Zollitsch, W. (2007). Methane production through anaerobic digestion of various energy crops grown in sustainable crop rotations. Bioresource Technology 98(17), 3204–3212. DOI: 10.1016/j.biortech.2006.07.007 DOI
  2. Heiermann, M. Plöchl, M. Linke, B. Schelle, H. (2002). Preliminary evaluation of some cereals as energy crops for biogas production. World Renewable Energy Congress VII.

All sources of the site: bibliography.

Other substrates in the group “Energy crops and whole-crop plants (WCS)”