BMP testingMunicipal and green waste, paper and textiles

Green / yard waste — BMP: 11 studies, weighted mean 177 m³ CH₄/t VS

Green waste from the maintenance of green spaces (grass, leaves, branches) is seasonal; its potential depends on the month of collection and the share of the woody fraction.

rating: neutral CH₄ ≈ 52 % (estimate)

Published 15 April 2025Updated 29 October 20263 min readFeedstockData Editorial Team

Illustration: FeedstockData (AI, Google Gemini)

Weighted mean: 177m³ CH₄/t VS
Range: 63–235m³ CH₄/t VS
Records: 11studies
Publications: 3sources
Temperatures: 37 °C, 38 °Cof the test

Methane in biogas

≈52–54% CH₄

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 1.2 % 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

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

Potential per tonne of fresh matter: moderate, but limited by the poor degradability of the organic matter (66 m³ CH₄/t); no particular threats to stability. Handling costs: sand, stones, shells, fibres, floating layer.

Why? Rating factors

Potential per tonne +1

+1potential 66 m³ CH₄/t fresh matter (BMP 177 × DM 44.6 % × VS 83.3 %); low degradability of VS (BMP 177 m³ CH₄/t VS) — points capped

Process stability 0

0no factors

Handling and costs −1

−0.5sand, stones, shells — sediment in the digester
−0.5fibres, floating layer — shredding and intensive mixing

Total points: 0 · 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 11 studies

Weighted mean Individual records

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 (177); 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

Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Holliger et al. (2017) · 1 DOI	103	—	Green waste — December	end point (model curve)
Holliger et al. (2017) · 2 DOI	147	—	Green waste — March	end point (model curve)
Holliger et al. (2017) · 3 DOI	156	—	Green waste — April	end point (model curve)
Holliger et al. (2017) · 4 DOI	207	—	Green waste — May	end point (model curve)
Holliger et al. (2017) · 5 DOI	227	—	Green waste — July	end point (model curve)
Holliger et al. (2017) · 6 DOI	235	—	Green waste — June	end point (model curve)
Lallement et al. (2023) · 1 DOI	63	38 °C · mesophilic	green waste	end point (model curve)
Lallement et al. (2023) · 2 DOI	178	38 °C · mesophilic	green waste	end point (model curve)
Lallement et al. (2023) · 3 DOI	212	38 °C · mesophilic	green waste	end point (model curve)
Lallement et al. (2023) · 4 DOI	219	38 °C · mesophilic	green waste	end point (model curve)
Li et al. (2013) DOI	183	37 °C · mesophilic	Yard waste	end point (model curve)
Weighted mean	177	arithmetic mean 176, SD 54

Typical composition

Dry matter (DM): 44.6% (range 34.4–80.6)
Volatile solids (VS): 83.3 % DM (range 77–93)
Nitrogen: 1.2 % DM
C/N ratio: 26.2

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 5 determinations, volatile solids: 3 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: Lallement et al. (2023); 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

fibrous
seasonal
sand and sediment
variable composition
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 176.7 m³ CH₄/t VS (SD 54.4; 11 records, 3 sources).
A seasonally available waste, potential depends on the month (Weiland 2010).

Drawbacks and risks

Woody fractions degrade poorly (Hendriks and Zeeman 2009).
Soil and stones require screening.

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

combines well
substrates: high alkalinity (buffer) — e.g. Cattle manure, Pig slurry, Cattle slurry, Duck slurry, Rumen and digestive tract content
Slurry supplies N, alkalinity and trace elements.^[1][2]

Dosing

No source threshold.

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”).

Sources of the process data

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

What it is and where it comes from

Green waste arises from the maintenance of parks, gardens, squares, cemeteries and road verges. It includes cut grass, leaves, weeds, shoots and branches. Green space managers and municipal companies collect it and send it to composting plants or biogas plants. The dataset includes samples of waste from different months of the year (from December to July), which makes it possible to see the effect of season on methane potential.

Properties relevant to digestion

The composition changes with the time of year: in spring and early summer young shoots and grass with a high content of readily available carbohydrates and protein predominate, while in autumn leaves and woody stems rich in lignin are added. Branches and thick pieces of wood hardly degrade at all. Dry matter is moderate or high, and the material needs size reduction because the fibres form a floating layer. Typical impurities are soil, stones, sand and litter. Grass spoils quickly after cutting, so long storage lowers the potential.

How to read the spread of results

The spread is large because the entry combines materials collected in different months, from different places and with different shares of grass, leaves and wood. The month of collection is one of the most important factors here. Storage, size reduction, temperature, inoculum and test duration also matter. Records from different months should not be merged into a single "typical value", although the builder displays them together.

In biogas plant practice

Green waste is valuable as an addition to municipal biowaste and to nitrogen-rich substrates, especially in the growing season. It requires screening out impurities, size reduction and, where appropriate, ensiling to even out availability over the year. Branches are better sent for composting or combustion. Green waste belongs to waste group 20, and its acceptance requires plant permits.

For logistics planners it is important that deliveries of green waste are uneven: the largest in May, June and autumn. A buffer in the form of a silage clamp or a tank allows the inflow to be evened out, and rapid processing limits losses and odour nuisance.

When deliveries are seasonal, ensiling can help, as it preserves most of the potential.

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 = 0.110 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

All sources of the site: bibliography.