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BMP testingEnergy crops and whole-crop plants (WCS)

Miscanthus (silvergrass) — BMP: 8 studies, weighted mean 229 m³ CH₄/t VS

Miscanthus is a perennial energy grass with a high yield and a high lignin content. The dataset covers fresh matter and silage, autumn and summer harvests and different species.

rating: goodCH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Katrin Schneider / korina.info / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping

Weighted mean
229m³ CH₄/t VS
Range
158–317m³ CH₄/t VS
Records
8studies
Publications
5sources
Temperatures
35 °C, 36 °C, 37 °C, 38 °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 (66 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer, slow degradation.

Why? Rating factors

Potential per tonne +2

  • +2potential 66 m³ CH₄/t fresh matter (BMP 229 × DM 30.8 % × VS 94.3 %)

Process stability 0

  • 0no factors

Handling and costs −1

  • −0.5fibres, floating layer — shredding and intensive mixing
  • −0.5slow degradation — long retention time

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

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

Add to the co-digestion calculator CSV data

BMP curves from 8 studies

Weighted mean Individual records

BMP curves: Miscanthus (silvergrass)Cumulative methane production over time for 8 records and the weighted mean of 229 m³ CH₄/t VS. 8 of the curves are model curves (first-order kinetics).01002003004000510152025303540time [d]m³ CH₄/t VSKaiser (2007) · 1: 204 m³ CH₄/t VS (model curve)Kaiser (2007) · 2: 223 m³ CH₄/t VS (model curve)Kaiser (2007) · 3: 277 m³ CH₄/t VS (model curve)Luna-delRisco et al. (2011): 317 m³ CH₄/t VS (model curve)Baute et al. (2018) · 1: 168 m³ CH₄/t VS (model curve)Baute et al. (2018) · 2: 230 m³ CH₄/t VS (model curve)Thomas et al. (2018): 158 m³ CH₄/t VS (model curve)Dubrovskis i Dubrovskis (2024): 236 m³ CH₄/t VS (model curve)mean229

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 (229); 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) · 120437 °C · mesophilicSilvergrass freshend point (model curve)
Kaiser (2007) · 222337 °C · mesophilicSilvergrass silageend point (model curve)
Kaiser (2007) · 327737 °C · mesophilicSilvergrass silageend point (model curve)
Luna-delRisco et al. (2011)31736 °C · mesophilicamur silvergrassend point (model curve)
Baute et al. (2018) · 1 DOI16838 °C · mesophilicMiscanthus x giganteus, October harvestend point (model curve)
Baute et al. (2018) · 2 DOI23038 °C · mesophilicMiscanthus x giganteus, July harvestend point (model curve)
Thomas et al. (2018) DOI15835 °C · mesophilicNon-pretreated miscanthus (Raw)end point (model curve)
Dubrovskis i Dubrovskis (2024) DOI23638 °C · mesophilicGrass miscanthusend point (model curve)
Weighted mean229arithmetic mean 227, SD 53

Typical composition

Dry matter (DM)
30.8% (range 25.2–93)
Volatile solids (VS)
94.3 % DM (range 92.5–94.6)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 4 determinations, volatile solids: 4 determinations. The DM range includes fresh samples as well as samples partly dried or dried before the test – for fresh material the lower part of the range applies, ideally your own measurement.

Sources: Kaiser (2007); Luna-delRisco et al. (2011).

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

  • fibrous
  • slowly degrading
  • seasonal
  • high dry matter
  • editorial classification

Advantages

  • Methane potential in the database: weighted mean 229 m³ CH₄/t VS (median 227; range 158–317; 8 records from 5 sources).

Drawbacks and risks

  • In a dry co-digestion test with cattle manure, the promising BMP results were not confirmed, which the authors attribute to high water absorption (Thomas 2018).
  • The lignocellulosic structure limits degradation (review by Hendriks 2009).

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

Dosing

No source-based limit on the share; Thomas 2018 studied co-digestion of miscanthus with manure in leach-bed reactors.

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”).
  • Lime (CaO) treatment for 5 days described in Thomas 2018

Sources of the process data

  1. Thomas, H.L.; Seira, J.; Escudié, R.; Carrère, H. (2018) Lime Pretreatment of Miscanthus: Impact on BMP and Batch Dry Co-Digestion with Cattle Manure. Molecules 23(7), 1608
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. Dahunsi, S. (2019) Mechanical pretreatment of lignocelluloses for enhanced biogas production: Methane yield prediction from biomass structural components. Bioresource Technology 280, 18–26
  4. Hendriks, A.T.W.M.; Zeeman, G. (2009) Pretreatments to enhance the digestibility of lignocellulosic biomass. Bioresource Technology
  5. Kaiser, F.L. (2007) Einfluss der stofflichen Zusammensetzung auf die Verdaulichkeit nachwachsender Rohstoffe beim anaeroben Abbau in Biogasreaktoren. Dissertation, Technische Universität München, Wissenschaftszentrum Weihenstephan
  6. Luna-delRisco, M.; Normak, A.; Orupõld, K. (2011) Biochemical methane potential of different organic wastes and energy crops from Estonia. Agronomy Research 9(1–2), 331–342
  7. Baute, K.; Van Eerd, L.L.; Robinson, D.E.; Sikkema, P.H.; Mushtaq, M.; Gilroyed, B.H. (2018) Comparing the Biomass Yield and Biogas Potential of Phragmites australis with Miscanthus x giganteus and Panicum virgatum Grown in Canada. Energies 11(9), 2198
  8. Dubrovskis, V.; Dubrovskis, D. (2024) Methane production from birch and maple leaves and miscanthus grass. Engineering for Rural Development 23
  9. FNR (2010). Guía sobre el Biogás – Desde la producción hasta el uso (hiszp. wydanie „Leitfaden Biogas”, GIZ 2013)

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

What it is and where it comes from

Miscanthus, in particular the hybrid M. × giganteus, is a tall perennial grass of Asian origin, grown as an energy crop. In Poland it is used mainly as a solid fuel (chips, briquettes), harvested in winter or early spring after drying out. In the context of biogas, earlier harvest is studied, in autumn or summer, when the biomass is wetter and more digestible. The dataset includes records for fresh matter and silage and for giant and sugar miscanthus, from harvests at different dates, including July and October.

Properties relevant to digestion

Miscanthus is strongly lignocellulosic, and the lignin share increases with the age of the plant, which lowers digestibility. Harvest during the growing season gives material with a higher content of water, protein and readily available compounds, but at the expense of the perennial yield (cutting too early can weaken the plantation). Ensiling is possible for younger biomass. Comminution is essential, and the material tends to form a floating crust. The silica content in the tissues can increase equipment abrasion.

How to read the spread of results

The spread results from the harvest date (summer versus autumn and winter), the species or variety, the age of the plantation, fertilisation and the form of the material (fresh, silage). Differences in sample comminution, inoculum, substrate-to-inoculum ratio, temperature and test length also have an effect. The dataset combines studies from different countries and climates (including Europe and Canada), which reinforces the variation. It is therefore a broad picture of the material, not a description of one specific plantation.

In biogas plant practice

For a biogas plant, miscanthus is a difficult substrate and usually less cost-effective than maize or grass silage, because it requires comminution, gives slower decomposition, and early harvest conflicts with its perennial growing cycle. It may make sense where a plantation already exists and has to be put to use, or where soil protection and biodiversity goals are important. The biomass should be shredded, ensiled and mixed with liquid substrates. A BMP test stating the harvest date is strongly recommended. If miscanthus is planned as a perennial crop for two uses, solid fuel and biogas, it must be decided in advance which harvest date is actually intended. Harvest during the growing season and winter harvest are mutually exclusive in the same year.

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. 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
  2. Luna-delRisco, M.; Normak, A.; Orupõld, K. (2011). Biochemical methane potential of different organic wastes and energy crops from Estonia. Agronomy Research 9(1–2), 331–342. https://www.semanticscholar.org/paper/25cf2d7bba4758136830a9a02caf3ecd997173bb source
  3. Baute, K.; Van Eerd, L.L.; Robinson, D.E.; Sikkema, P.H.; Mushtaq, M.; Gilroyed, B.H. (2018). Comparing the Biomass Yield and Biogas Potential of Phragmites australis with Miscanthus x giganteus and Panicum virgatum Grown in Canada. Energies 11(9), 2198. DOI: 10.3390/en11092198 DOI
  4. Thomas, H.L.; Seira, J.; Escudié, R.; Carrère, H. (2018). Lime Pretreatment of Miscanthus: Impact on BMP and Batch Dry Co-Digestion with Cattle Manure. Molecules 23(7), 1608. DOI: 10.3390/molecules23071608 DOI
  5. Dubrovskis, V.; Dubrovskis, D. (2024). Methane production from birch and maple leaves and miscanthus grass. Engineering for Rural Development 23. DOI: 10.22616/erdev.2024.23.tf106 DOI

All sources of the site: bibliography.

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