In the face of fossil fuel depletion and increasingly serious climate change, biofuels are becoming a sustainable solution to reduce greenhouse gas emissions and ensure energy security. Bioethanol, one of the most popular biofuels, can be produced from a variety of feedstocks such as corn, sugarcane and sweet sorghum. Among them, sweet sorghum is considered a promising feedstock due to its fast growth rate, adaptability to drought conditions and high sugar content in the stem.
1. Potential of sweet sorghum in bioethanol production
Bioethanol currently accounts for around two-thirds of total global biofuel production. According to the International Energy Agency (IEA), global bioethanol production has increased from 100 billion litres in 2010 to 170 billion litres in 2022, with an annual growth rate of 6.1%. However, biofuel production needs to increase significantly to stay on track with the 2050 net zero emissions (NZE) scenario and deliver the associated emissions reductions. Biofuel production reaches more than 10 EJ in 2030 under the NZE scenario, requiring an average growth rate of around 11% per year. The use of advanced feedstocks must also expand: biofuels produced from waste and residues and non-food energy crops should meet more than 40% of total biofuel demand in 2030.
Sweet sorghum is a potential source of raw materials thanks to its outstanding characteristics such as: (i) The plant can grow well in arid conditions, helping to reduce dependence on irrigation water; (ii) The stem contains 12-20% sugar, making the bioethanol fermentation process more effective than other raw materials; The average yield/biomass reaches 50-80 tons/ha, providing a large amount of raw materials for ethanol production ; (iv) The harvest cycle of sweet sorghum usually lasts only 3-5 months, compared to 12-18 months for sugar cane.
In addition, compared to other feedstocks such as corn and sugarcane, sweet sorghum has lower production costs because it does not require fertile arable land and is less dependent on chemical fertilizers.
2. Methods of bioethanol production from sweet sorghum
There are several methods for producing bioethanol from sweet sorghum, including:
- Fermentation from stem juice: Sorghum stems contain high sugar content, can be pressed to extract juice to ferment directly into ethanol.
- Using starch from the grain: Sorghum grains contain starch that can be converted into sugar through enzymatic hydrolysis, then fermented into ethanol.
- Conversion of lignocellulose from waste residue: The residue after pressing the juice can be treated by chemical or enzymatic methods to separate cellulose and hemicellulose into simple sugars, then fermented into ethanol.
Each method has certain advantages and limitations, of which lignocellulose hydrolysis is the most complicated due to high technological requirements.
3. Application of nanotechnology in bioethanol production
Nanotechnology is being researched and applied to improve the efficiency of bioethanol production from sweet sorghum. Some important technologies include:
- Nanoenzyme: Immobilizing enzymes on the surface of nanoparticles helps hydrolyze cellulose and hemicellulose faster, improving the efficiency of converting biomass into fermentable sugar.
- Nanoparticles (NPs): Nanoparticles are used to improve biomass pretreatment, helping to break down lignocellulose structure more efficiently and reduce the amount of enzymes required during hydrolysis.
- Nano sensors: Allows real-time monitoring and adjustment of the fermentation process, helping to optimize ethanol production performance.
Research by Oraby et al. (2023) showed that the use of metal oxide nanoparticles in biomass pretreatment can increase the cellulose hydrolysis efficiency by up to 30% compared to traditional methods. In addition, the application of nanoenzymes can reduce the amount of enzyme required for bioethanol production by 40%, which significantly reduces costs.
4. Challenges and opportunities
Although nanotechnology offers many benefits in bioethanol production, there are still some challenges such as (i) The application of nanotechnology requires advanced equipment and large research and development costs; (ii) Developing countries may have difficulty accessing and implementing nanotechnology in large-scale production; (iii) Some nanomaterials may have impacts on the ecosystem if not handled properly. However, with advances in research and supportive government policies, nanotechnology promises to play an important role in the commercialization of sustainable bioethanol production.
In summary, bioethanol production from sweet sorghum combined with nanotechnology is a potential direction in the field of renewable energy. Thanks to its fast growth ability, low cost and high biomass yield, sweet sorghum can become a sustainable alternative to fossil fuels. The application of nanotechnology in the production process helps to improve biomass conversion efficiency, reduce costs and optimize ethanol production efficiency. Although there are many challenges, with advances in research and technology investment, sweet sorghum can become one of the leading feedstocks for the bioethanol industry in the future.
References
Bhuyan, N., Dutta, A., Mohan, R., Bora, N., & Kataki, R. (2021). Advances in nanotechnology for biofuel production. In Nanomaterials - Application in biofuels and bioenergy production systems (pp. 533-562).
International Energy Agency (IEA). Biofuel Annual Report 2023.
OECD/FAO (2021), “OECD-FAO Agricultural Outlook”, OECD agriculture statistics (database), https://doi.org/10.1787/agr-outl-data-en
Oraby, S., Hegazy, M.I., Labeeb, H.M., & Mahd, A. (2023). Iron oxide nanoparticle-based pretreatment for simultaneously elevated hydrolysis efficiency and methanization augmentation of Chlorella vulgaris biomass. Algal Research , 70 , 102972. https://doi.org/10.1016/j.algal.2023.102972
Punia, P., Kumar, S. (2025). A critical review on enhanced bioethanol production from sweet sorghum using nanotechnology. Energy Nexus, 17, 100339.
Research group of Microbiology and Food safety