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BMP testingAlgae and aquatic plantssingle study (6 samples)

Lipid-extracted Nannochloropsis gaditana — BMP: 6 studies, weighted mean 412 m³ CH₄/t VS

Nannochloropsis gaditana biomass after lipid extraction is a residue of an algal biorefinery; it was examined under mesophilic and thermophilic conditions in a single study.

CH₄ ≈ 58 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Illustration: FeedstockData (AI, Google Gemini)

Weighted mean
412m³ CH₄/t VS
Range
315–475m³ CH₄/t VS
Records
6single study (6 samples)
Publications
1source
Temperatures
35 °C, 55 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.8 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein-rich (process classification)) 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 6 studies

Weighted mean Individual records

BMP curves: Lipid-extracted Nannochloropsis gaditanaCumulative methane production over time for 6 records and the weighted mean of 412 m³ CH₄/t VS. 6 of the curves are model curves (first-order kinetics).02004006000510152025303540time [d]m³ CH₄/t VSCapson-Tojo et al. (2017) · 1: 315 m³ CH₄/t VS (model curve)Capson-Tojo et al. (2017) · 2: 365 m³ CH₄/t VS (model curve)Capson-Tojo et al. (2017) · 3: 390 m³ CH₄/t VS (model curve)Capson-Tojo et al. (2017) · 4: 460 m³ CH₄/t VS (model curve)Capson-Tojo et al. (2017) · 5: 470 m³ CH₄/t VS (model curve)Capson-Tojo et al. (2017) · 6: 475 m³ CH₄/t VS (model curve)mean412

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 (412); 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
Capson-Tojo et al. (2017) · 1 DOI31555 °C · thermophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Capson-Tojo et al. (2017) · 2 DOI36555 °C · thermophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Capson-Tojo et al. (2017) · 3 DOI39035 °C · mesophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Capson-Tojo et al. (2017) · 4 DOI46055 °C · thermophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Capson-Tojo et al. (2017) · 5 DOI47035 °C · mesophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Capson-Tojo et al. (2017) · 6 DOI47535 °C · mesophilicNannochloropsis gaditana · pretreatment: particle size reduction/sample preparation (MY-D: physical treatment)end point (model curve)
Weighted mean412arithmetic mean 412, SD 66

Typical composition

Dry matter (DM)
95.4% (range 91.1–97.5)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 3 determinations, volatile solids: 0 determinations. Samples were tested dried/air-dry – the DM refers to the material in the test, not to fresh material.

Sources: Capson-Tojo et al. (2017).

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

  • protein-rich
  • nitrogen-rich
  • saline
  • variable composition
  • high dry matter
  • editorial classification

Advantages

  • Methane yield in the compendium: median 425 (range 315–475) m³ CH₄/t VS, 6 records from 1 papers (weighted mean 412).
  • Converting biomass after lipid extraction to methane can recover more energy than the cell lipids contained (Sialve et al. (2009))
  • Biomass after lipid extraction was digested under mesophilic and thermophilic conditions (Capson-Tojo et al. (2017))

Drawbacks and risks

  • The high protein content of the cells causes release of ammonia, which can be toxic to the process (Sialve et al. (2009); Rajagopal et al. (2013))
  • The presence of sodium in marine species may impair digester operation (Sialve et al. (2009))

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

  • Do not dry the biomass before feeding: drying lowered biogas production to about 80% (Mussgnug et al. (2010))
  • Monitor ammonia (high protein) and, for marine species, sodium (Sialve et al. (2009))

Sources of the process data

  1. Anaerobic co-digestion of algal sludge and waste paper to produce methane
  2. Anaerobic digestion of microalgae as a necessary step to make microalgal biodiesel sustainable
  3. A critical review on inhibition of anaerobic digestion process by excess ammonia
  4. Mesophilic and thermophilic anaerobic digestion of lipid-extracted microalgae N. gaditana for methane production
  5. Microalgae as substrates for fermentative biogas production in a combined biorefinery concept

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

What it is and where it comes from

Nannochloropsis gaditana is a marine microalga grown, among other reasons, for its lipids, including omega-3 fatty acids. After lipid extraction (with solvents or mechanical methods), a solid biomass remains, rich in protein and carbohydrates. The dataset contains several records from a single study in which the biomass after extraction was digested at mesophilic (35 °C) and thermophilic (55 °C) temperatures. It is therefore a by-product of a biorefinery, not an agricultural feedstock.

Properties relevant to digestion

Extraction breaks some of the cells and removes lipids, the component with the highest methane yield per gram, but also a source of risk of inhibition by long-chain fatty acids. The residue is enriched in protein, which lowers the C/N ratio and risks ammonia release, particularly in thermophilic tests, where free ammonia is more toxic. Solvent residue (e.g. after chemical extraction) can inhibit microorganisms. The marine origin of the biomass also means salts may be present.

How to read the spread of results

The spread results from differences in test temperature (mesophilic or thermophilic), the extraction method and replicates within a single study. The range of results therefore shows sensitivity to conditions rather than variability of the feedstock. Also important are the degree of cell disruption, solvent residues, protein content, the substrate-to-inoculum ratio, adaptation of the inoculum to ammonia and the test length. Results from one laboratory must be supplemented with data from other studies before they are generalised.

In biogas plant practice

The residue after lipid extraction could be part of an algal biorefinery concept in which, once the valuable products have been obtained, the remainder is sent to the digester. In practice this requires ammonia control (co-digestion with material of a higher C/N ratio, moderate loading) and removal of solvent residues. On an industrial scale such a biorefinery in Europe remains at the research and demonstration stage. The legal status depends on the origin of the residue and the installation's permits.

For comparison with whole biomass, which contains lipids, the residue after extraction is safer with regard to the LCFA risk, but usually has a lower overall potential, because it has lost the most energy-rich component.

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 = 0.102 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. Capson-Tojo, G.; Torres, A.; Muñoz, R.; Bartacek, J.; Jeison, D. (2017). Mesophilic and thermophilic anaerobic digestion of lipid-extracted microalgae N. gaditana for methane production. Renewable Energy 105, 539–546. DOI: 10.1016/j.renene.2016.12.052 DOI

All sources of the site: bibliography.

Other substrates in the group “Algae and aquatic plants”