Bagasse, as a green and renewable polymer material, has broad prospects for environmental protection. It is the fibrous residue left after sugarcane is crushed and pressed to extract juice, accounting for 24%–27% of the total weight of the sugarcane. It is one of the largest agricultural waste products in the world. China, as the third-largest sugarcane producer globally, produces more than 20 million tons annually.

1. Composition and Characteristics of Bagasse

1.1 Composition of Bagasse

Bagasse mainly consists of cellulose, hemicellulose, and lignin, with small amounts of protein, starch, and soluble sugars.

1.2 Key Characteristics of Bagasse

Sugar production enterprises are seasonal and large-scale. Bagasse has the advantages of centralized sourcing, large output, ease of collection, small transportation radius, and relatively stable composition. Its uniform properties meet the requirements of raw material centralization, continuity, and uniformity for industrial applications.

2. Comprehensive Utilization of Bagasse

As shown in Table 1, bagasse is not only a natural polymer material and a treasure trove of green chemicals, but it also contains abundant biomass energy, making it a high-quality renewable raw material for sustainable development. Both domestic and international sugar production workers are exploring new pathways for the comprehensive utilization of bagasse.

2.1 Utilization Status Abroad

Abroad, the main uses of bagasse include:

1. As a fuel for power generation: In countries like Mauritius, Brazil, India, Australia, Thailand, Cuba, and many others with sugar industries, bagasse is used as fuel to generate electricity, meeting the energy needs of sugar mills. Some power plants are even connected to the grid or supply electricity to nearby farms, reducing the consumption of coal and other resources and lowering electricity costs.
2. Pulp and paper production: In 1926, the United States began using bagasse to produce pulp for paperboard in Louisiana, marking the beginning of bagasse as a substitute for wood in the paper industry. Over the years, bagasse has become one of the most utilized agricultural fibers for paper production. Currently, countries like Argentina, Colombia, Mexico, India, and Australia use bagasse to produce newsprint and various types of cultural paper, or mix bleached bagasse pulp with bleached softwood pulp to produce high-quality coated paper, etc.
3. Animal feed production: In Brazil, the United States, Australia, and other countries, sugar mills utilize bagasse as animal feed for cows, sheep, fish, and shrimp after high-temperature, high-pressure cooking or fermentation treatment.
4. Production of engineered wood products: Bagasse’s chemical composition is similar to wood, making it an excellent raw material for board production. As early as the 1960s, many countries producing sugarcane had established bagasse particle board factories, such as the Va-eherie factory in the U.S., the Tueuman factory in Argentina, and the CienfuegosJ factory in Cuba. These boards are widely used in construction, veneers, packaging, mid-to-high-end furniture, interior decoration, sound panels, mobile homes, etc.

2.2 Domestic Utilization Status and Existing Problems

Currently, the main uses of bagasse in China are:

1. As fuel for boilers: The traditional method of handling bagasse is burning it as fuel for power generation in sugar mills. In domestic sugar production, when the coal-to-bagasse ratio drops to 5%, the bagasse consumption in sugar mills accounts for about 65%–70% of the total bagasse produced.
2. Pulp and paper production: Apart from being used as fuel, pulp and paper production is the most significant utilization of bagasse in China's sugar mills. Currently, there are projects such as the 95,000-ton bagasse pulp paper project in Lincang, Yunnan, the 200,000-ton cultural paper project by the Guangxi Nongken Sugar Group, and others. These projects have successfully turned bagasse into newsprint and other types of paper, generating good economic and social benefits.
3. Production of engineered wood products: Bagasse’s chemical composition makes it an excellent material for board production. In 1982, the Guangzhou Sugar Research Institute developed a hot-press technology for producing bagasse particle boards. Many sugar mills in Guangdong, Guangxi, and other provinces have set up production lines for these boards, which are mainly used in furniture, construction templates, packaging boxes, and speaker panels.
4. Production of green and environmentally friendly tableware: For example, the Shuangfei Green Tableware Factory in Mashan County, Guangxi, produces green tableware using bagasse. In recent years, research on fully biodegradable tableware made from bagasse and thermoplastic starch, in collaboration with the Guangzhou Sugar Research Institute and Zhejiang Ningbo Jialian Plastic Technology Co., Ltd., has made good progress. Under the context of bio-refinery industry development, bagasse is also being used to produce bioethanol, biodiesel, xylitol, furfural, activated carbon, and other products. This is currently a hot area of research.

Although significant progress has been made in the comprehensive utilization of bagasse in China, there are still some shortcomings. The main issues are:

1. Small scale and wide distribution of sugar mills: Currently, there are more than 300 sugar mills in China, scattered across provinces like Guangxi, Yunnan, Guangdong, Hainan, and Guizhou. The utilization of bagasse for pulp and paper production and engineered wood products is mainly concentrated in regions with a high density of sugar mills, such as Guangxi and Guangdong. However, in some remote areas, due to transportation difficulties and other reasons, the residual bagasse has not been effectively and reasonably utilized, leading to waste and environmental pollution, which affects the enthusiasm of local sugar mills for energy saving.
2. An unreasonable phenomenon in sugar mills: During the sugar cane crushing season, sugar mills often have large amounts of residual bagasse while still needing to burn large amounts of firewood. This is because sugar mills are seasonal, and they need to slowly heat and cool the boiler during startup and shutdown to ensure its safe operation. In these two processes, coal, bagasse particles, and packaged bagasse cannot meet the requirements for slow and steady heating and cooling of the furnace, so firewood must be used. For example, two sugar mills in Guangdong with daily cane crushing capacities of 3,000 tons and 5,000 tons need 500 tons and 650 tons of firewood, respectively, at the start of each crushing season. With over 300 large-scale sugar mills nationwide, this results in a need for 160,000–200,000 tons of firewood annually. This represents a blind spot for energy saving and bagasse utilization in China’s sugar mills. Not only does it severely restrict energy-saving efforts, raising production costs, but it also leads to the cutting down of large amounts of firewood, causing serious environmental damage.
3. Transportation, storage, and utilization issues: Fresh bagasse is an irregularly shaped, loose particle with low density and poor combustion characteristics, making it difficult to transport, store, and use. This restricts its potential as a biomass energy source.
4. For us, the development of bagasse is still in its early stages. We look forward to its application in more fields! For the sustainable development of the Earth, we should also avoid disposable plastic products and choose more environmentally friendly, biodegradable alternatives!