Characterisation of Congolese Aquatic Biomass and Their Potential as a Source of Bioenergy

Tania S Mayala,Bernard M’Passi-Mabiala,Aaron E Brown,Andrew B Ross,Jon C Lovett,James M Hammerton,Maryse D Nkoua Ngavouka,Dick H Douma

doi:10.3390/biomass2010001

Tania S Mayala, Bernard M’Passi-Mabiala + Show 6 more

Open Access

https://doi.org/10.3390/biomass2010001

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Journal: Biomass	Publication Date: Jan 5, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: Marien Ngouabi University, University of Leeds

Abstract

This study assesses the bioenergy potential of two types of aquatic biomass found in the Republic of Congo: the green macroalgae Ulva lactuca (UL) and Ledermanniella schlechteri (LS). Their combustion behaviour was assessed using elemental and biochemical analysis, TGA, bomb calorimetry and metal analysis. Their anaerobic digestion behaviour was determined using biochemical methane potential (BMP) tests. The average HHV for LS is 14.1 MJ kg−1, whereas UL is lower (10.5 MJ kg−1). Both biomasses have high ash contents and would be problematic during thermal conversion due to unfavourable ash behaviour. Biochemical analysis indicated high levels of carbohydrate and protein and low levels of lipids and lignin. Although the lipid profile is desirable for biodiesel production, the levels are too low for feasible extraction. High levels of carbohydrates and protein make both biomasses suitable for anaerobic digestion. BMP tests showed that LS and UL have an average of 262 and 161 mL CH4 gVS−1, respectively. The biodegradability (BI) of LS and UL had an average value of 76.5% and 43.5%, respectively. The analysis indicated that these aquatic biomasses are unsuitable for thermal conversion and lipid extraction; however, conversion through anaerobic digestion is promising.

Highlights

Publisher’s Note: MDPI stays neutralBiomass is the main source of energy in the rural areas of most developing countries, and globally biomass contributes approximately 14% of the world’s energy supply [1,2].International commitments to Sustainable Development Goal 7, which is to “Ensure access to affordable, reliable, sustainable and modern energy for all”, combined with a continued shift away from fossil fuels and increasing populations, ensure that biomass will remain a major source of energy in the future
The results indicate that Ledermanniella schlechteri (LS) contains a higher carbon content than Ulva lactuca (UL), with a carbon content ranging between 36.2–40.0% and 19.1–30.9%
The levels of nitrogen in LS ranged between 2.1% and 2.7%, whereas N-content was lower for UL, ranging between 1.5% and 2.2%

Summary

Introduction

International commitments to Sustainable Development Goal 7, which is to “Ensure access to affordable, reliable, sustainable and modern energy for all”, combined with a continued shift away from fossil fuels and increasing populations, ensure that biomass will remain a major source of energy in the future. Biomass and charcoal are used extensively for cooking in the Republic of Congo, resulting in poor air quality and associated health impacts. This firewood and charcoal is often unsustainably sourced from the Congo Basin forest, resulting in deforestation and reduced biodiversity and carbon storage capacity [3]. The identification of alternative biomass feedstocks can relieve the pressure on these forests and may promote the development of alternative conversion routes such as using biogas for cooking. The physio-chemical properties which significantly affect the choice of biomass for conversion to bioenergy include biochemical composition

Results

Discussion

Conclusion