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BMP testingFruit, vegetables and their residues

Potato peels — BMP: 5 studies, weighted mean 234 m³ CH₄/t VS

Potato peelings are a processing waste rich in starch and sugars, easily digested; at a high share they require control of acidity and foam.

rating: neutralCH₄ ≈ 56 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Ssemmanda will / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping

Weighted mean
234m³ CH₄/t VS
Range
177–267m³ CH₄/t VS
Records
5studies
Publications
3sources
Temperatures
35 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.6 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 4.1 % 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

neutral — editorial rating for biogas plantsNo clear advantages — worth charging a fee for accepting it

Potential per tonne of fresh matter: low (19 m³ CH₄/t); process risk: acidification. Handling costs: fibres, floating layer.

Why? Rating factors

Potential per tonne 0

  • ±0potential 19 m³ CH₄/t fresh matter (BMP 234 × DM 9.2 % × VS 86.5 %)

Process stability −0.5

  • −0.5acidification: rapid degradation / acidic pH, risk of VFA accumulation, needs buffering

Handling and costs −0.5

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

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: medium · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 5 studies

Weighted mean Individual records

BMP curves: Potato peelsCumulative methane production over time for 5 records and the weighted mean of 234 m³ CH₄/t VS. 5 of the curves are model curves (first-order kinetics).0100200300051015202530time [d]m³ CH₄/t VSGunaseelan (2004): 267 m³ CH₄/t VS (model curve)Liang i McDonald (2015): 239 m³ CH₄/t VS (model curve)Achinas et al. (2019) · 1: 177 m³ CH₄/t VS (model curve)Achinas et al. (2019) · 2: 191 m³ CH₄/t VS (model curve)Achinas et al. (2019) · 3: 218 m³ CH₄/t VS (model curve)mean234

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 (234); 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
Gunaseelan (2004) DOI26735 °C · mesophilicPotato peelsend point (model curve)
Liang i McDonald (2015) DOI23935 °C · mesophilicpotato peel wasteend point (model curve)
Achinas et al. (2019) · 1 DOI177—Potato peel waste, ISR 1 (R3)end point (model curve)
Achinas et al. (2019) · 2 DOI191—Potato peel waste, ISR 4 (R5)end point (model curve)
Achinas et al. (2019) · 3 DOI218—Potato peel waste, ISR 2 (R4)end point (model curve)
Weighted mean234arithmetic mean 218, SD 36

Typical composition

Dry matter (DM)
9.2% (range 9.2–9.2)
Volatile solids (VS)
86.5 % DM (range 82–90.9)
Nitrogen
4.1 % DM
C/N ratio
10.7

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. C/N was calculated as the ratio of C and N content (% DM) from the same source. DM from a single determination – indicative value.

Sources: Gunaseelan (2004); Liang et al. (2015).

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

  • easily degradable
  • carbon-rich
  • low in nitrogen
  • poor in trace elements
  • seasonal
  • fibrous
  • editorial classification

Advantages

  • Methane yield in the compendium: median 218 (range 177–267) m³ CH₄/t VS, 5 records from 3 papers (weighted mean 234).
  • Preliminary lactic fermentation of peelings gave higher methane production than the peelings alone (Liang et al. (2015))

Drawbacks and risks

  • Increasing the substrate load (after lactic fermentation) from 6.4 to 9.1% DM inhibited methane production; VFA accumulation was studied (Liang et al. (2015))

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

Dosing

The sources do not give a safe share of this substrate. For the digestion of potato peelings after preliminary lactic fermentation, increasing the substrate load from 6.4 to 9.1% DM inhibited methane production (Liang et al. 2015) — a pointer on the solids content in the reactor, not on the share in the feed.

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

Sources of the process data

  1. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
  2. Biochemical methane potential and biodegradability of complex organic substrates
  3. Anaerobic digestion of pre-fermented potato peel wastes for methane production
  4. Biochemical methane potential of fruits and vegetable solid waste feedstocks
  5. Biogas Potential from the Anaerobic Digestion of Potato Peels: Process Performance and Kinetics Evaluation
  6. Lab-scale anaerobic digestion of cassava peels: the first step of energy recovery from cassava waste and water hyacinth
  7. Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
  8. Effect of particle size on biogas generation from biomass residues

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

What it is and where it comes from

Potato peelings arise in potato processing plants: in the production of chips, crisps, mash and salads, and in institutional catering. In Poland potato processing is well developed, and peelings are one of the basic wastes. The peelings are wet, the size of the fraction depends on the peeling technology, and their composition differs from whole tubers because of the larger share of skin.

Properties relevant to digestion

Peelings contain starch, soluble sugars, protein and fibre from the cork layer of the skin. The fat content is low and lignin moderate, depending on the amount of skin. Starch hydrolyses quickly and forms acids, so with a sudden increase in the dose there is a risk of acidification of the digester. Steam peelings are often a hot slurry with a high content of gelatinised starch, which further speeds up decomposition. Potatoes contain glycoalkaloids (solanine and chaconine), which concentrate in the skin and sprouts, but at typical shares they are not a problem. Frequent troubles are foaming and sand from the soil adhering to the tubers.

How to read the spread of results

The dataset contains several records from several sources, including mesophilic results and ones with no temperature stated. The records come from an experiment with different loadings in reactors (designated ISR). Differences depend on the potato variety, the peeling method (steam, mechanical, chemical), the share of flesh in the peelings, comminution and the inoculum. For a material with rapid hydrolysis, the result depends strongly on the substrate-to-inoculum ratio.

In biogas plant practice

Peelings are a valued supplement to the feed: they have a stable composition, but require careful dosing and a good buffer, e.g. in the form of slurry. Storage is limited, because the material spoils quickly and pre-ferments, producing odours and acids. It is usually delivered in batches from the plant, which eases quality control. Waste from plant processing is waste, and the installation must hold appropriate authorisation to accept it. In the event of foaming, reducing the dose and ensuring even mixing can help.

For stable digester operation it is beneficial to introduce the peelings several times a day in small portions rather than all at once; a load spread in this way limits pH fluctuations and the risk of foaming, especially with hot peelings from steam peeling.

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 = 0.245 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. 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
  2. Liang, S.; McDonald, A.G. (2015). Anaerobic digestion of pre-fermented potato peel wastes for methane production. Waste Management 46, 197–200. DOI: 10.1016/j.wasman.2015.09.029 DOI
  3. Achinas, S.; Li, Y.; Achinas, V.; Euverink, G.J.W. (2019). Biogas Potential from the Anaerobic Digestion of Potato Peels: Process Performance and Kinetics Evaluation. Energies 12(12), 2311. DOI: 10.3390/en12122311 DOI

All sources of the site: bibliography.

Other substrates in the group “Fruit, vegetables and their residues”