In an "Illustrated History of How Sugar Conquered the World," an article that Kristy Mucci published in Saveur, she argues that understanding Western history requires understanding sugar. Not only has sugarcane fulfilled humanity's insatiable desire for sweetness, but it has also served as a spice, a medicine, and a symbol of power and oppression.
Today, sugarcane is the world's largest crop in terms of production quantity. Over 120 countries produce nearly 180 million metric tons of sugar, 80% of which is harvested from tropical and subtropical sugarcane. While the focus of production is the plant's sweet juice, increasing attention is also paid to bagasse. With a name derived from the Spanish word bagazo, originally meaning "rubbish," bagasse is the residual byproduct of sugarcane stalk processing. Ten tons of sugarcane produce about three tons of bagasse, which is composed of 45% cellulose, 28% hemicellulose, 20% lignin, in addition to other materials. In fact, the composition of bagasse fibers is similar to that of wood, with a high water content, and bagasse is often put to practical use—primarily as a biofuel source to power sugarcane mills.
But a growing number of scientists and product manufacturers are also developing new applications for bagasse, including using it to develop new building materials and other products that retain the fiber's sequestered carbon while offsetting the use of less environmentally responsible alternatives. For instance, Celotex offers a bagasse-based soft board called Caneboard, which is produced in the company's New Orleans facility.
Bagasse was first used to make commercial building products nearly a century ago. CSR Limited (short for Colonial Sugar Refining Company), a leading building products manufacturer in New South Wales, Australia, was founded in 1855. According to the Pyrmont History Group, the CSR mills had a surplus of bagasse in the 1930s—a time when building material demands accelerated after the Great Depression. In response to the changing market, the company began to produce a commercial product called Caneite made from pulped bagasse fiber. CSR rolled this raw material to ensure homogeneous thickness and density, then heat-cured and cut it into boards for wall linings, floor underlays, acoustics, and other applications. The product was sufficiently successful that annual production grew to 10 million square feet by 1939, motivating the company to invest in other building materials (and eventually shift out of the sugar refining business altogether).
Bagasse can also be used in another form. When the chaff is burned as a fuel source, the resulting residue is sugarcane bagasse ash. Like fly ash, SCBA can be used in Portland cement as a supplementary material. The ash consists primarily of silicon dioxide—an ingredient that has been thoroughly tested in Portland cement blends—and may replace 20% to 50% of the cement without adversely affecting its performance. Researchers have experimented with SCBA in concrete, mortar, bricks, and clay tiles. Since the ash is relatively lightweight, it can also reduce the mass of building blocks. Another study determined that SCBA increases chloride- and sulfate-resistance in construction materials.
In addition, Bagasse can be used as a plastic substitute—particularly for one-time-use products. The material's inherent biodegradability makes it preferable to petroleum-based polymers that accumulate in our oceans and take centuries to break down. Bagasse compares favorably to, say, the corn-based PLA bioplastic in that it requires less processing energy, decomposes more rapidly, and takes advantage of a preexisting waste stream. Scientists at Northeastern University have recently developed a bagasse-based material with improved moisture resistance. By adding the nontoxic alkyl ketene dimer, the researchers were able to create a material with improved wet mechanical strength during its first use (such as disposable tableware) while remaining safely biodegradable. Additionally, the manufacturing process has a 97% lower carbon footprint than the production of conventional consumer plastics.
As these examples demonstrate, bagasse offers compelling advantages when it is used to make building materials and consumer products. It is a significant source of biowaste that may be repurposed in various applications with lower emissions and less waste than the materials it replaces. That said, using more bagasse—as with any biomaterial—should be considered within a larger framework of future needs and sustainable agricultural practices. For example, sugarcane is increasingly used to make ethanol-based fuel in addition to sugar and bioplastics, suggesting there may be greater demand for the resource in the future. Bagasse not only invites architects and designers to develop creative uses for a material that was once regarded as trash, but it also asks them to consider the broader industrial ecology of renewable materials in general.
