BMP testingStraws and crop residues

Sugarcane straw — BMP: 3 studies, weighted mean 300 m³ CH₄/t VS

Sugarcane straw consists of leaves and tops left after the stalks are harvested. Lignocellulosic, dry and hard to degrade, it requires chopping and usually pretreatment.

CH₄ ≈ 52 % (estimate)

Published 14 February 2023Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Jonathan Wilkins / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean: 300m³ CH₄/t VS
Range: 199–383m³ CH₄/t VS
Records: 3studies
Publications: 2sources
Temperatures: 38 °Cof the test

Methane in biogas

≈51–54% 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 (carbohydrate-dominated (no protein or fat characteristics)) 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

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 (300); 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
Janke et al. (2015) · 1 DOI	199	38 °C · mesophilic	sugarcane straw S-2	end point (model curve)
Janke et al. (2015) · 2 DOI	234	38 °C · mesophilic	sugarcane straw S-1	end point (model curve)
López-Dávila et al. (2022) DOI	383	—	Cane straw	end point (model curve)
Weighted mean	300	arithmetic mean 272, SD 98

Process properties

fibrous
slowly degrading
carbon-rich
low in nitrogen
seasonal
editorial classification

Advantages

Methane potential in the database: weighted mean 300 m³ CH₄/t VS (median 234; range 199–383; 3 records from 2 sources).

Drawbacks and risks

Janke 2015 describes the kinetic challenges of digesting sugarcane waste — a long HRT or pretreatment is required.

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

combines well
group: Animal excreta (slurry, manure, poultry litter)
Manure/slurry supplies N and buffer.^[1][2]

Dosing

No source-based dose limits; an entry mainly for tropical regions.

Practical requirements

Size reduction, pretreatment (Janke 2015)

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

Sugarcane straw (cane straw, trash) comprises the leaves, leaf sheaths and tops of the plants which, during harvest, are separated from the stalks destined for juice pressing. In mechanical harvesting without prior burning of the field, a large part of this biomass remains in the field or is transported together with the stalks. It is a separate stream from bagasse, i.e. the pressed residue after juice extraction. In Europe this material does not occur; it is significant for tropical and subtropical countries.

Properties relevant to digestion

Sugarcane straw is a lignocellulosic biomass with low moisture after drying out, rich in cellulose and hemicelluloses, with lignin hindering enzyme access to the polysaccharides. This translates into slow hydrolysis and the need for a long retention time. The low protein content causes a high C/N ratio, which requires combining with nitrogen substrates, for example animal excreta. The material is light and bulky, so transport logistics are often costly, and contamination with soil and sand increases the abrasiveness for equipment.

How to read the spread of results

The dataset comprises few records, including samples from one study (labelled S-1 and S-2) and a result from another publication that does not give the temperature. The differences between samples arise from cane variety, plant age, region and growing conditions, the share of tops relative to leaves and the degree of soil contamination. Chopping also has an effect: finer particles increase availability, but change the behaviour of the material in the digester. With such a narrow base the results should be treated as indicative.

In biogas plant practice

In Polish conditions this substrate has no practical significance, but it is important for comparisons with other straws. In cane-growing countries the straw is sometimes collected as fuel, which is a competing use. If it goes to digestion, it requires chopping, nitrogen supplementation and consideration of pretreatment. Like other lignocellulosic materials, it works best as a component of a mix with a liquid substrate. Because the dataset contains few records and the spread between samples is significant, these results should not be transferred directly to other regions or varieties. For realistic plans to use such biomass, a BMP test carried out on material from the target source is needed, with a description of the chopping and inoculum conditions.

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 = 0.136 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.