About usContact

BMP testingEnergy crops and whole-crop plants (WCS)

Switchgrass — BMP: 3 studies, weighted mean 180 m³ CH₄/t VS

Switchgrass (Panicum virgatum) is a perennial North American prairie grass, grown for biomass. In the compilation it appears in a small number of records from different studies.

CH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Jebulon / Wikimedia Commons, licence CC0 1.0, source file; changes: cropping

Weighted mean
180m³ CH₄/t VS
Range
122–246m³ CH₄/t VS
Records
3studies
Publications
3sources
Temperatures
35 °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

not rated — editorial rating for biogas plants

Not rated: the dry matter in the data refers to a sample dried for the test, not to the material as delivered. 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

BMP curves: SwitchgrassCumulative methane production over time for 3 records and the weighted mean of 180 m³ CH₄/t VS. 3 of the curves are model curves (first-order kinetics).01002003000510152025303540time [d]m³ CH₄/t VSLabatut et al. (2011): 122 m³ CH₄/t VS (model curve)Li et al. (2013): 246 m³ CH₄/t VS (model curve)Baute et al. (2018): 173 m³ CH₄/t VS (model curve)mean180

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 (180); 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
Labatut et al. (2011) DOI12235 °C · mesophilicswitchgrassend point (model curve)
Li et al. (2013) DOI24637 °C · mesophilicSwitchGrassend point (model curve)
Baute et al. (2018) DOI17338 °C · mesophilicPanicum virgatum (species mean)end point (model curve)
Weighted mean180arithmetic mean 180, SD 62

Typical composition

Dry matter (DM)
91.3% (range 91.3–91.3)
Volatile solids (VS)
96.3 % DM (range 95.7–97)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 1 determination, volatile solids: 2 determinations. Samples were tested dried/air-dry – the DM refers to the material in the test, not to fresh material.

Sources: Labatut et al. (2011); Li et al. (2013).

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
  • slowly degrading
  • editorial classification

Advantages

  • Methane potential in the database: weighted mean 180 m³ CH₄/t VS (median 173; range 122–246; 3 records from 3 sources).

Drawbacks and risks

  • Size reduction is necessary for lignocellulosic grass (Hendriks 2009).
  • Small database (3 records).

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

Dosing

No source-based dose limits.

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

  1. Li, Y.; Zhang, R.; Liu, G.; Chen, C.; He, Y.; Liu, X. (2013) Comparison of methane production potential, biodegradability, and kinetics of different organic substrates. Bioresource Technology 149, 565–569
  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. Labatut, R.A.; Angenent, L.T.; Scott, N.R. (2011) Biochemical methane potential and biodegradability of complex organic substrates. Bioresource Technology 102(3), 2255–2264
  6. 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
  7. 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

Switchgrass (Panicum virgatum) is a perennial grass of the North American prairie, grown as an energy crop for solid fuels and biofuels. It tolerates poorer soils well and has a large biomass yield in warm and temperate climates. In Europe, including Poland, it is grown experimentally or on a small scale. The compilation contains several records from several studies, including one from a Canadian study in which an average for the species is given.

Properties relevant to digestion

Switchgrass is a typical perennial grass with a high lignin and cellulose content, little protein and a wide C/N ratio. Harvested late, after frost and drying, it has low moisture and low digestibility, whereas harvested in summer it is green and better suited to ensiling. Degradation in the digester is slow, and the material tends to form a floating crust. Size reduction is necessary. In combination with slurry a better nitrogen balance is obtained.

How to read the spread of results

The records come from different studies and different temperatures (from 35 to 38 °C), and one of them is an average for the species from several varieties. The spread therefore includes differences in variety, harvest date, plantation age, fertilisation and methodology. Studies from different decades use different protocols. There are not enough data here to assess variability in practice, so each result is only an indicative reference point.

In biogas plant practice

At biogas plants switchgrass is a supplementary substrate, less productive than maize silage. The asset is its perennial nature and tolerance of poorer conditions, the drawback difficult degradation. The biomass should be harvested at the appropriate date, size-reduced and ensiled if it is green. In the ration it behaves like other lignocellulosic grasses. Cost-effectiveness depends on yield and price, and the decision should be based on a BMP test of your own batch. In planning crops it must be remembered that the first years after establishing a plantation give a low yield, and full productivity is reached only after several seasons. For a biogas plant this means the need to secure other substrates while the plantation is reaching full yield.

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. Labatut, R.A.; Angenent, L.T.; Scott, N.R. (2011). Biochemical methane potential and biodegradability of complex organic substrates. Bioresource Technology 102(3), 2255–2264. DOI: 10.1016/j.biortech.2010.10.035 DOI
  2. Li, Y.; Zhang, R.; Liu, G.; Chen, C.; He, Y.; Liu, X. (2013). Comparison of methane production potential, biodegradability, and kinetics of different organic substrates. Bioresource Technology 149, 565–569. DOI: 10.1016/j.biortech.2013.09.063 DOI
  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

All sources of the site: bibliography.

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