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BMP testingBy-products of the agri-food industry

Grape stalks — BMP: 3 studies, weighted mean 137 m³ CH₄/t VS

Grape stems are lignified, tannin-rich residues left after separating the fruit from the bunches; they ferment slowly and require thorough chopping.

CH₄ ≈ 53 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Mingo Hagen / Wikimedia Commons, licence CC BY 2.0, source file; changes: cropping

Weighted mean
137m³ CH₄/t VS
Range
98–180m³ CH₄/t VS
Records
3studies
Publications
3sources
Temperatures
35 °C, 40 °C, 55 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.3 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein from total nitrogen (N 2 % DM × 6.25)) 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: no dry matter or volatile solids in the data. 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: Grape stalksCumulative methane production over time for 3 records and the weighted mean of 137 m³ CH₄/t VS. 3 of the curves are model curves (first-order kinetics).0501001502000510152025303540time [d]m³ CH₄/t VSDa Ros et al. (2016): 133 m³ CH₄/t VS (model curve)Dinuccio et al. (2010): 98 m³ CH₄/t VS (model curve)Gunaseelan (2004): 180 m³ CH₄/t VS (model curve)mean137

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 (137); 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
Da Ros et al. (2016) DOI13355 °C · thermophilicgrapeend point (model curve)
Dinuccio et al. (2010) DOI9840 °C · mesophilicGrape stalksend point (model curve)
Gunaseelan (2004) DOI18035 °C · mesophilicpeduncle (stalk of gRape bunch)end point (model curve)
Weighted mean137arithmetic mean 137, SD 41

Typical composition

Volatile solids (VS)
90.4 % DM (range 88.9–91.9)
Nitrogen
2 % DM

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 0 determinations, volatile solids: 2 determinations. No DM in the sources – the calculator has to ask for a value.

Sources: Dinuccio et al. (2010); Gunaseelan (2004).

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
  • low in nitrogen
  • carbon-rich
  • high dry matter
  • contains inhibitors
  • 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 Substraty.pl BMP dataset: weighted mean 137.0 m³ CH₄/t VS (SD 41.1; 3 records, 3 sources).
  • Grape stalks: a dry, durable material, no risk of acidification - does not burden the VFA system (Hendriks and Zeeman 2009).

Drawbacks and risks

  • Tannins bind proteins and may inhibit enzymes (Chen et al. 2008).

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

Dosing

No source limits on the dose for this substrate.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

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”).
  • Control floating crust and sediment: when solids are fed directly into the digester, the risk of their formation depends on the substrate (FNR 2010, Ch. 3).

Sources of the process data

  1. Hagos et al. (2017). Anaerobic co-digestion process for biogas production: progress, challenges and perspectives. Renew. Sustain. Energy Rev.
  2. Weiland (2010). Biogas production: current state and perspectives. Appl. Microbiol. Biotechnol.
  3. Rajagopal, Masse, Singh (2013). A critical review on inhibition of anaerobic digestion process by excess ammonia. Bioresour. Technol.
  4. Hendriks, Zeeman (2009). Pretreatments to enhance the digestibility of lignocellulosic biomass. Bioresour. Technol.
  5. 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

During the processing of grapes into wine, the fruit is separated from the stems and stalks of the bunches in the process of destemming. Stems make up several per cent of the mass of the grapes and are a waste of vineyards and wineries. In Poland winemaking is developing, but the scale is small compared with the countries of southern Europe, so the substrate is significant mainly locally and as data from the literature.

Properties relevant to digestion

Stems are lignified: they contain cellulose, hemicellulose and lignin, and also tannins and other polyphenols. The content of simple sugars is small, but residual juice may add sugar. The structure hinders hydrolysis, so without chopping the rate of degradation is slow. Tannins bind proteins and can inhibit enzymes and microorganisms, although at a typical share in the feed they do not block the process. The high C/N ratio encourages combining with slurry. Stems store well in the dry state.

How to read the spread of results

The dataset contains several records from several sources: thermophilic results (55 °C), 40 °C and mesophilic ones (35 °C). The discrepancy in temperatures in itself makes comparison difficult. The results also depend on grape variety, ripeness, the method of destemming, chopping, test duration and inoculum. With lignified material the result depends strongly on whether the test ended after a plateau was reached.

In biogas plant practice

Stems are introduced after grinding, in a small share, together with pomace or other winery wastes. In vineyard practice they are often composted or returned to the soil. Deliveries are concentrated in the grape harvest period, so the material must be stored; in the dry state this is easy. Waste from wineries is waste, but on small wine-growing farms it may be treated in accordance with the rules for agricultural waste, provided this complies with the regulations.

For small vineyards, using stems in a biogas plant is rarely profitable because of the small quantities and dispersal. Composting is more realistic, and at larger wineries possibly joint processing with pomace, with which the stems usually form one batch of waste.

When planning it is also worth remembering that stems may be contaminated with residues of plant protection products used in vineyards, which is an additional argument for checking the origin of the batch.

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. Da Ros, C.; Cavinato, C.; Bolzonella, D.; Pavan, P. (2016). Renewable energy from thermophilic anaerobic digestion of winery residue: Preliminary evidence from batch and continuous lab-scale trials. Biomass and Bioenergy 91, 150–159. DOI: 10.1016/j.biombioe.2016.05.017 DOI
  2. Dinuccio, E.; Balsari, P.; Gioelli, F.; Menardo, S. (2010). Evaluation of the biogas productivity potential of some Italian agro-industrial biomasses. Bioresource Technology 101(10), 3780–3783. DOI: 10.1016/j.biortech.2009.12.113 DOI
  3. Gunaseelan, V. (2004). Biochemical methane potential of fruits and vegetable solid waste feedstocks. Biomass and Bioenergy 26(4), 389–399. DOI: 10.1016/j.biombioe.2003.08.006 DOI

All sources of the site: bibliography.

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