South Africa is one of the countries with a high carbon footprint, due to excessive use of fossil-based oil for energy. By utilising agricultural-based resources to generate biofuels, agriculture can assist the country to move away from this fossil fuel dependence and provide energy security.

A study by the Agricultural Research Council’s (ARC) Institute for Agricultural Engineering aims to investigate and understand the potential of using selected cultivars of sunflower as biomass for renewable (green) diesel production – in part (i.e. oil or heads) or as a whole (total plant).

An in-depth physiological (digital plant phenomics) and chemical assessment is being conducted (e.g. cellulose, hemicellulose, lignin, sugar content, protein and fatty acid composition) on a subset of plants to be used as feedstock, in addition to a more comprehensive study of catalytic thermal pre-treatment of the different biomass. The near-infrared spectroscopy (DA 7250) has been used to assess moisture content, oil, oleic and linoleic acid composition of the sunflower seed.

The findings from this study will provide insight into the physical and physiological factors related to oil accumulation, moisture accumulation, plant biomass yield, and other lignocellulosic biomass traits in sunflower – all required to determine the optimal time within sunflower production to harvest the biomass to produce a specific renewable diesel product with known chemical signature.

Setting a model for development

Hydrotreating of sunflower oil and plant material will set a model for development of a commercial batch and continuous co-hydroprocessing systems using South African government approved feedstocks. The project combines ARC expertise in feedstock production, development and the diversity in the germplasm collection with reaction engineering and development at ARC-Institute for Agricultural Engineering.

Co-feeding the hydroprocessing reactor with other raw material such as waste residues from soya bean processing could possibly result in higher renewable (green) diesel yields using this clean technology. – Dr Idan Chiyanzu, Dr Dirk Swanevelder and Primrose Magama, ARC-Institute for Agricultural Engineering