Ability of NIR spectroscopy to determine the biomethane potential from organic wastes and agricultural products


CALL: 2008

DOMAIN: SR - Sustainable Uses and Sources of Energy

FIRST NAME: Philippe

LAST NAME: Delfosse




KEYWORDS: Biogas, Bioenergy

START: 2009-05-01

END: 2012-04-30

WEBSITE: https://www.list.lu/

Submitted Abstract

Biomethanation plans commonly use organic substrates, agricultural commodities and animal effluents tofeed anaerobic digesters and produce biogas. The biogas consists mainly in methane (CH4 : +/- 60%), theonly source of energy, and carbon dioxide (CO2 : +/- 40%). The gas also contains trace compounds suchas hydrogen sulphur (H2S). Farmers involved in biomethanation get forages and organic wastes analysedin order to reduce ration costs, maximise methane production and profit. The true objective of a substrateanalysis is therefore to predict the biomethane potential (BMP) and indirectly the digester performance.The determination of BMP from organic substrates is tedious and very time consuming. It typicallyrequires a digestion test elapsing over a minimum of 30 days. This long period delays drastically thedecision of the farmer to incorporate or not a newly proposed substrate and therefore, the farmer can missa lucrative opportunity. Additionally, a prediction of the H2S potential from a substrate is also veryvaluable information because H2S is a major source of corrosion for the digesters and the engines of thecombined heat and power (CHP) units. Last but not least, a quick information on the digestibility of thesubstrates to be incorporated in the digester rations is a key element to optimize the feeding rate in amanner that leads to high energy conversion while respecting favourable conditions for this complexbiological process. It is therefore crucial to determine the digestibility kinetics since a highly and fastdigestible substrate can lead to the production of a massive amount of organic acid leading to acidosisand the arrest of the digester consequently causing an important economic loss for the farmer.Near infrared spectroscopy (NIRS) has been used for decades to predict feed and food quality. Thisanalytical technique uses a source producing light of known wavelength pattern (commonly 800-2500nm) to obtain a complete picture of the organic composition of the analysed substrate. The basic principalis that different chemical bonds in the organic matter absorb or emit light of different wavelengths whenthe substrate is irradiated. NIRS offers the advantages of being non-destructive and fast and it allowssimultaneous determination of different attributes.Considering the wide and successful use of NIRS in analysing forages and food, the BIONIR project hasthe objective (1) to assess its ability to predict the BMP, the digestion kinetics, and the H2S emission foragricultural commodities and residues, and (2) to evaluate various energy crops and maize cultivarsgrown under the agro-climatic conditions prevailing in Luxembourg and Belgium, with an emphasis onelucidating which part of the maize plant (corn rich in starch versus stem and leaves rich in fibres), ismore adequate for biomethanation. To achieve these objectives, a partnership has been set up thatinvolves various specific expertises; (1) the CRP-GL for the determination of the BMP and the substratecomposition, (2) the CRA-W for the NIRS calibration and evaluation, (3) the ASTA and CIPF forproviding agricultural substrates produced in a comparable manner in Luxembourg and Belgium.

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