Bioethanol Production from Sweet Sorghum Feedstocks

Sweet sorghum (Sorghum bicolor) is emerging as a versatile and sustainable feedstock for bioethanol production. As a hardy C4 cereal, it combines high biomass yield with drought tolerance and low nutrient requirements, enabling cultivation on marginal soils that are unsuitable for food crops. Ethanol can be derived from both the juice fraction—rich in sucrose, glucose and fructose—and the lignocellulosic residues, which require pretreatment and enzymatic saccharification. Harvesting typically targets the peak sugar accumulation in the stalk, after which mechanical extraction of juice is followed by fermentation using yeasts or engineered microbes. Residual bagasse is subjected to chemical or biological pretreatments to break down lignin and hemicellulose structures, enhancing access to cellulose. Subsequent enzymatic hydrolysis releases fermentable sugars that are converted to ethanol. Integrated biorefinery approaches aim to valorise all components of the plant, combining ethanol production with by-product streams such as animal feed, biogas or platform chemicals. Advances in breeding and genetic engineering are driving the development of cultivars with increased sugar content, modified cell-wall architecture and improved stress resilience. Techno-economic and life-cycle assessments underscore the global significance of sweet sorghum as a low-carbon alternative to fossil fuels, particularly in regions facing water scarcity or land-use competition.

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Bioethanol Production from Sweet Sorghum Feedstocks publication trend

The graph below shows the total number of articles in bioethanol production from sweet sorghum feedstocks across all publications each year (not limited to Nature Index journals).

Technical terms

C4 photosynthesis: A carbon-fixation pathway in certain plants that concentrates CO2 in specialised cells, enhancing water and nutrient use efficiency under high light and temperature.

Lignocellulosic biomass: The complex structural material in plant cell walls, composed of cellulose, hemicellulose and lignin, requiring pretreatment to access fermentable sugars.

Pretreatment: A chemical, physical or biological process applied to biomass to disrupt lignin and hemicellulose networks, improving enzymatic accessibility.

Saccharification: The enzymatic hydrolysis of cellulose and hemicellulose into simple sugars such as glucose and xylose, suitable for microbial fermentation.

Fermentable sugars: Monosaccharides released from biomass that can be metabolised by microorganisms to produce ethanol.

Biorefinery: An integrated facility that converts biomass into fuels, power, heat and value-added chemicals using multiple process streams.

References

1. Sweet sorghum as biofuel feedstock: recent advances and available resources. Biotechnology for Biofuels and Bioproducts (2017).
2. Bioethanol Production from Biomass of Selected Sorghum Varieties Cultivated as Main and Second Crop. Energies (2020).
3. Bioethanol Potential of Energy Sorghum Grown on Marginal and Arable Lands. Frontiers in Plant Science (2018).
4. Optimization of Continuous Solid-State Distillation Process for Cost-Effective Bioethanol Production. Energies (2020).
5. Technical Feasibility and Comprehensive Sustainability Assessment of Sweet Sorghum for Bioethanol Production in China. Sustainability (2018).