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BMP testingBy-products of the agri-food industry

Hemp hurds and dust — BMP: 2 studies, weighted mean 212 m³ CH₄/t VS

Hemp shives and dust are woody residues of hemp fibre, rich in lignin and cellulose; digestion is slow and requires size reduction or pretreatment.

rating: goodCH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Florian Gerlach (Nawaro) / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean
212m³ CH₄/t VS
Range
184–239m³ CH₄/t VS
Records
2studies
Publications
2sources
Temperatures
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 (protein from total nitrogen (N 0.8 % 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

good — editorial rating for biogas plantsStable, usually accepted without a fee

Potential per tonne of fresh matter: very high (145 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer, slow degradation.

Why? Rating factors

Potential per tonne +3

  • +3potential 145 m³ CH₄/t fresh matter (BMP 212 × DM 88.1 % × VS 78 %)

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

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

Add to the co-digestion calculator CSV data

BMP curves from 2 studies

Weighted mean Individual records

BMP curves: Hemp hurds and dustCumulative methane production over time for 2 records and the weighted mean of 212 m³ CH₄/t VS. 2 of the curves are model curves (first-order kinetics).01002003000510152025303540time [d]m³ CH₄/t VSLallement et al. (2023): 184 m³ CH₄/t VS (model curve)Matassa et al. (2020): 239 m³ CH₄/t VS (model curve)mean212

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 (212); 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
Lallement et al. (2023) DOI18438 °C · mesophilichemp dustend point (model curve)
Matassa et al. (2020) DOI239—Unretted hurdsend point (model curve)
Weighted mean212arithmetic mean 212, SD 39

Typical composition

Dry matter (DM)
88.1% (range 88.1–88.1)
Volatile solids (VS)
78 % DM (range 78–78)
Nitrogen
0.8 % DM
C/N ratio
49.5

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: 1 determination. C/N was calculated as the ratio of C and N content (% DM) from the same source. Samples were tested dried/air-dry – the DM refers to the material in the test, not to fresh material.

Sources: Lallement et al. (2023).

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
  • 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 211.7 m³ CH₄/t VS (SD 38.6; 2 records, 2 sources).
  • Hemp shives: a dry, durable material, no risk of acidification - does not burden the VFA system (Hendriks and Zeeman 2009).

Drawbacks and risks

  • Dust - risk of dust generation (a physical property of the material).

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

Fibre hemp (Cannabis sativa) is grown for fibre and seeds. During stem processing the bast fibre is separated from the woody core, that is, the shives, and dust also arises on this occasion. Shives are used as bedding, insulation material (hempcrete) or briquettes, so at a biogas plant they occur as a waste or a product of low commercial value. In Poland fibre hemp is grown on a limited scale, so the stream is small.

Properties relevant to digestion

Shives are a lignocellulosic material with a high lignin and cellulose content and a low content of soluble sugars and protein. The structure is compact and poorly accessible to enzymes, which causes slow hydrolysis and a low share of rapidly degradable fraction. Unlike sugar-rich materials there is no risk of acidification, but the gas potential depends on size reduction and pretreatment. Dust is finer and may contain more bast fibre particles. A high C/N ratio means the material combines well with slurry as a source of nitrogen and buffer. Dry dust poses a dust hazard.

How to read the spread of results

The dataset contains several records from several sources: hemp dust under mesophilic conditions and non-retted shives from a second source. Differences result from the hemp variety, harvest date, decortication method, degree of size reduction and the duration of the test, which for woody materials must be long. Retting, that is, partial biological decomposition of the stems in the field, changes the composition, so the result for retted and non-retted shives is not interchangeable.

In biogas plant practice

Shives can be added at a small share to co-digestion, after milling, together with materials that degrade quickly. Without pretreatment (steam, alkaline, mechanical) utilisation is partial. The material stores well if it is dry, and its low bulk density raises transport costs. Competition from other uses often decides that it does not go to a biogas plant. The legal status depends on the origin: waste from processing is subject to the waste rules.

An additional barrier is the low bulk density of shives, which makes transport and feeding to the digester difficult. It is usually necessary to briquette them, mill them or mix them with a liquid feed, which raises costs and limits the cost-effectiveness of using this material.

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. 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
  2. Matassa, S.; Esposito, G.; Pirozzi, F.; Papirio, S. (2020). Exploring the Biomethane Potential of Different Industrial Hemp (Cannabis sativa L.) Biomass Residues. Energies 13(13), 3361. DOI: 10.3390/en13133361 DOI

All sources of the site: bibliography.

Other substrates in the group “By-products of the agri-food industry”