BMP testingEnergy crops and whole-crop plants (WCS)

Sunflower, whole crop — BMP: 15 studies, weighted mean 287 m³ CH₄/t VS

Sunflower as a whole plant is a tall energy crop harvested for silage, with a high yield but variable composition. The dataset covers many harvest dates and varieties.

rating: very good CH₄ ≈ 52 % (estimate)

Published 13 December 2024Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Björn S. / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean: 287m³ CH₄/t VS
Range: 154–454m³ CH₄/t VS
Records: 15studies
Publications: 3sources
Temperatures: 36 °C, 38 °Cof the test

Methane in biogas

≈51–53% 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 0.9 % 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

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 (136 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer.

Why? Rating factors

Potential per tonne +3

+3potential 136 m³ CH₄/t fresh matter (BMP 287 × DM 53.3 % × VS 89.2 %)

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: medium · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 15 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 (287); 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 (3)

Records and sources

Download CSV

Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Amon et al. (2007) · 1 DOI	154	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 2 DOI	190	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 3 DOI	194	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 4 DOI	206	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 5 DOI	220	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 6 DOI	252	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 7 DOI	271	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 8 DOI	272	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 9 DOI	291	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 10 DOI	300	38 °C · mesophilic	Sunflower whole crop Silage	end point (model curve)
Amon et al. (2007) · 11 DOI	335	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 12 DOI	428	38 °C · mesophilic	Sunflower	end point (model curve)
Amon et al. (2007) · 13 DOI	454	38 °C · mesophilic	Sunflower	end point (model curve)
Lallement et al. (2023) DOI	291	38 °C · mesophilic	Sunflower	end point (model curve)
Luna-delRisco et al. (2011)	296	36 °C · mesophilic	sunflower	end point (model curve)
Weighted mean	287	arithmetic mean 277, SD 83

Typical composition

Dry matter (DM): 53.3% (range 15.6–91)
Volatile solids (VS): 89.2 % DM (range 88.5–90)
Nitrogen: 0.9 % DM
C/N ratio: 46.3

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 2 determinations, volatile solids: 2 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); 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

seasonal
fibrous
editorial classification

Advantages

Methane potential in the database: weighted mean 287 m³ CH₄/t VS (median 272; range 154–454; 15 records from 3 sources).
Whole sunflower plants described in Amon 2007, Lunadelrisco 2011, Lallement 2023.

Drawbacks and risks

Wide spread of values (15 records).

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

combines well
group: Animal excreta (slurry, manure, poultry litter)
Co-digestion with excreta (slurry/solid manure) is the standard arrangement for plant biomass: they supply alkalinity and microflora.^[1][2]

Dosing

No source-based dose limits.

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

Common sunflower (Helianthus annuus) is grown mainly for its oilseeds, but it is also studied as an energy crop in the form of the whole plant harvested before seed maturity. It is tall, has a strong root system and tolerates periodic water shortages well, which distinguishes it from maize. The dataset contains records from several studies: over a dozen values from an experiment in which sunflower was grown in an energy crop rotation and harvested at different dates, and individual values for silage and dried plant.

Properties relevant to digestion

The composition changes during the season. The young plant is moist and relatively digestible, and as it matures the share of the lignified stalk rises and, from flowering, so does that of oily seeds in the heads, which contribute lipids. Fats increase the energy potential, but in large quantities can be a burden for the process; in typical whole-crop silage their share is moderate. Ensiling sunflower is more difficult than maize because of its lower sugar content and high buffering capacity, so it requires attention in choosing the harvest stage and dry matter content. The stalk is thick and requires thorough chopping.

How to read the spread of results

The most important factor is the harvest date, and hence the proportion of stalk, leaves and heads with seeds. Further influences are the variety (oil, sugar), fertilisation, plant density, the year and the form of the material: fresh, silage or dried. A considerable number of records come from one series of experiments, so they are not independent observations. To this are added differences in chopping, inoculum, substrate-to-inoculum ratio and test temperature (36 to 38 °C in the individual studies).

In biogas plant practice

Sunflower is a supplement to maize silage in drier regions and on poorer soils. Harvesting with a forage harvester at the start of flowering or early seed set gives the best compromise between yield and quality. The silage should be tightly covered and compacted, and in the mix treated like other plant silages, with control of volatile fatty acids. Profitability depends on yields in the given region. Before introducing it into the ration it is worth carrying out a BMP test, linking it to the harvest stage.

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 = 0.085 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.