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BMP testingGrasses, green forage and fodder plants

Meadow hay — BMP: 16 studies, weighted mean 279 m³ CH₄/t VS

Meadow hay is dried grass with a high dry matter and fibre content, considered as a substrate with stable properties. The dataset rests on several studies.

rating: very goodCH₄ 53 %

Published Updated 3 min readFeedstockData Editorial Team

Photo John H Darch / Wikimedia Commons, licence CC BY-SA 2.0, source file; changes: cropping

Weighted mean
279m³ CH₄/t VS
Range
180–380m³ CH₄/t VS
Records
16studies
Publications
7sources
Temperatures
35 °C, 36 °C, 37 °C, 38 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.3 kWh/m³ of biogas

measured mean of 1 study BMP; 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

very good — editorial rating for biogas plantsWorth accepting even for free or with a payment to the supplier

Potential per tonne of fresh matter: very high (213 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer.

Why? Rating factors

Potential per tonne +3

  • +3potential 213 m³ CH₄/t fresh matter (BMP 279 × DM 82.4 % × VS 92.5 %)

Process stability 0

  • 0no factors

Handling and costs −0.5

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

Total points: 2.5 · 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 16 studies

Weighted mean Individual records

BMP curves: Meadow hayCumulative methane production over time for 16 records and the weighted mean of 279 m³ CH₄/t VS. 16 of the curves are model curves (first-order kinetics).01002003004005000510152025303540time [d]m³ CH₄/t VSLehtomaki (2005) · 1: 180 m³ CH₄/t VS (model curve)Lehtomaki (2005) · 2: 230 m³ CH₄/t VS (model curve)Lehtomaki (2006) · 1: 370 m³ CH₄/t VS (model curve)Lehtomaki (2006) · 2: 380 m³ CH₄/t VS (model curve)Lehtomaki (2004): 230 m³ CH₄/t VS (model curve)Kaiser (2007) · 1: 188 m³ CH₄/t VS (model curve)Kaiser (2007) · 2: 191 m³ CH₄/t VS (model curve)Kaiser (2007) · 3: 198 m³ CH₄/t VS (model curve)Kaiser (2007) · 4: 219 m³ CH₄/t VS (model curve)Kaiser (2007) · 5: 230 m³ CH₄/t VS (model curve)Kaiser (2007) · 6: 268 m³ CH₄/t VS (model curve)Lallement et al. (2023): 289 m³ CH₄/t VS (model curve)Luna-delRisco et al. (2011) · 1: 253 m³ CH₄/t VS (model curve)Luna-delRisco et al. (2011) · 2: 286 m³ CH₄/t VS (model curve)Luna-delRisco et al. (2011) · 3: 319 m³ CH₄/t VS (model curve)Dubrovskis et al. (2018): 355 m³ CH₄/t VS (model curve)mean279

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 (279); 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.

  • Show the remaining records in the legend (4)

Records and sources

Download CSV
SourceBMP
m³ CH₄/t VS		CH₄ in biogas
% vol., measured		TemperatureSampleCurve
Lehtomaki (2005) · 1180—35 °C · mesophilicGrass hay (75% thymothy 25% meadow fescue)end point (model curve)
Lehtomaki (2005) · 2230—35 °C · mesophilicGrass hay (75% thymothy 25% meadow fescue)end point (model curve)
Lehtomaki (2006) · 1370—35 °C · mesophilicGrass hay 67.5% timothy 22.5% meadow fescue 10% Red cloverend point (model curve)
Lehtomaki (2006) · 2380—35 °C · mesophilicGrass hay 67.5% timothy 22.5% meadow fescue 10% Red cloverend point (model curve)
Lehtomaki (2004)230—35 °C · mesophilicGrass hay (75% thymothy 25% meadow fescue)end point (model curve)
Kaiser (2007) · 1188—37 °C · mesophilicgrass hayend point (model curve)
Kaiser (2007) · 2191—37 °C · mesophilicgrass hayend point (model curve)
Kaiser (2007) · 3198—37 °C · mesophilicgrass hayend point (model curve)
Kaiser (2007) · 4219—37 °C · mesophilicgrass hayend point (model curve)
Kaiser (2007) · 5230—37 °C · mesophilicgrass hayend point (model curve)
Kaiser (2007) · 6268—37 °C · mesophilicgrass hayend point (model curve)
Lallement et al. (2023) DOI289—38 °C · mesophilichay meadowend point (model curve)
Luna-delRisco et al. (2011) · 1253—36 °C · mesophilichay · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Luna-delRisco et al. (2011) · 2286—36 °C · mesophilichay · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Luna-delRisco et al. (2011) · 3319—36 °C · mesophilichay · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Dubrovskis et al. (2018) DOI35553.3 %38 °C · mesophilicGrass hay pelletsend point (model curve)
Weighted mean27953.3 %arithmetic mean 262, SD 66

Typical composition

Dry matter (DM)
82.4% (range 20.2–91.3)
Volatile solids (VS)
92.5 % DM (range 91.4–94.2)
Nitrogen
2.6 % DM
C/N ratio
26

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: CROPGEN D4, MY-D); dry matter: 13 determinations, volatile solids: 8 determinations. C/N was calculated as the ratio of C and N content (% DM) from the same source. 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: Lehtomaki (2005); Lehtomaki (2006); Lehtomaki (2004); Kaiser (2007); Lallement et al. (2023); 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
  • high dry matter
  • forms a floating layer
  • seasonal
  • editorial classification

Advantages

  • Methane potential in the database: weighted mean 279 m³ CH₄/t VS (median 242; range 180–380; 16 records from 7 sources).

Drawbacks and risks

  • The chemical composition of hay strongly affects digestibility (Kaiser 2007) — hay cut late has a lower value.

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

Dosing

No source-based dose limits; dosing of hay pellets is described in Dubrovskis 2018.

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. Dubrovskis, V.; Plume, I.; Straume, I. (2018) Investigations of biogas production potential from grass hay pellets. Engineering for Rural Development
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. Lehtomaki, A. Ronkainen, O.M. Rintala, J.A. (2005) Developing storage methods for optimised methane production from energy crops in northern conditions. ADSW 2005 Conference Proceedings Vol 1. 101-108
  4. Lehtomaki, A. Viinikainen, T.A. Rintala, J.A (2006) Screening boreal energy crops and crop residues for methane biofuel production. Submitted to Biomass and Bioenergy
  5. Lehtomaki, A. Viinikainen, T.A. Ronkainen, O.M. Alen, R. Rintala, J.A. (2004) Effect of pretreatments on methane production potential of energy crops and crop residues. Proceedings Anaerobic Digestion Conference 1016-1021
  6. Hendriks, A.T.W.M.; Zeeman, G. (2009) Pretreatments to enhance the digestibility of lignocellulosic biomass. Bioresource Technology
  7. Kaiser, F.L. (2007) Einfluss der stofflichen Zusammensetzung auf die Verdaulichkeit nachwachsender Rohstoffe beim anaeroben Abbau in Biogasreaktoren. Dissertation, Technische Universität München, Wissenschaftszentrum Weihenstephan
  8. 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
  9. 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
  10. 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

Meadow hay is made from grasses (often timothy, meadow fescue, ryegrass) and other meadow plants which, after cutting, are dried in the field to a moisture content that allows safe storage. It is usually used as winter fodder. At a biogas plant it may appear as a surplus or as lower-quality material, for example obtained from damp or overly late cuts. The dataset contains records from several studies, including studies on timothy-fescue hay.

Properties relevant to digestion

Drying halts biological processes and limits losses, but some of the readily available sugars are lost in the field through plant respiration, and in rain leaching occurs. Hay has a high dry matter content, a high share of fibre (cellulose, hemicelluloses and lignin) and lower digestibility than young green forage. The rate of degradation is therefore slower, and chopping matters. The material is light and bulky, and in the digester it may form a scum layer. Thanks to its low moisture it is stable in storage, provided it is dry.

How to read the spread of results

Hay is a highly variable material. The result depends on botanical composition (the share of grasses, legumes and herbs), the developmental stage at mowing, the conditions of drying and storage, and the age of the hay. The dataset contains records for timothy-fescue hay with varying clover addition and other samples. Sample chopping, inoculum, the substrate-to-inoculum ratio and test length are added to this. Different studies therefore describe a slightly different material under a common name.

In biogas plant practice

Hay is rarely used as a regular substrate, because it has fodder value and requires costly harvesting. It may make sense where the material is damp, spoiled or surplus. Before feeding it must be chopped and assessed for mould and contamination. Its share in the ration is limited by scum formation and mixing requirements. It is best combined with a liquid substrate such as slurry. When planning supplies it is worth carrying out a BMP test of your own batch. Where hay comes from many suppliers, it is good to set simple acceptance criteria: maximum moisture, absence of mould and contamination, and information on plant composition, which makes it easier to maintain constant feed quality and to compare biogas production results.

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

Results after pretreatment (38) — excluded from the mean
SourceBMP
m³ CH₄/t VS		PretreatmentSample
Lehtomaki (2004)270—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)270—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)260—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)190—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)130—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)100—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)140—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)130—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)260—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)250—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)270—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)230—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)140—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)210—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)170—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)270—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)200—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)230—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)250—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2004)230—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)280—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)280—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)310—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)280—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)260—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)170—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)270—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)230—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)230—Grass hay (75% thymothy 25% meadow fescue)
Lehtomaki (2005)240—Grass hay (75% thymothy 25% meadow fescue)

Bibliography

  1. Lehtomaki, A. Ronkainen, O.M. Rintala, J.A. (2005). Developing storage methods for optimised methane production from energy crops in northern conditions. ADSW 2005 Conference Proceedings Vol 1. 101-108.
  2. Lehtomaki, A. Viinikainen, T.A. Rintala, J.A (2006). Screening boreal energy crops and crop residues for methane biofuel production. Submitted to Biomass and Bioenergy.
  3. Lehtomaki, A. Viinikainen, T.A. Ronkainen, O.M. Alen, R. Rintala, J.A. (2004). Effect of pretreatments on methane production potential of energy crops and crop residues. Proceedings Anaerobic Digestion Conference 1016-1021.
  4. 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
  5. 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
  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. https://www.semanticscholar.org/paper/25cf2d7bba4758136830a9a02caf3ecd997173bb source
  7. Dubrovskis, V.; Plume, I.; Straume, I. (2018). Investigations of biogas production potential from grass hay pellets. Engineering for Rural Development. DOI: 10.22616/erdev2018.17.n413 DOI

All sources of the site: bibliography.

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