Sugarcane is the green gold of the century, it is already used to make sugar, rum, fuel, vegetable plastic…
Sugar cane is not only used to make rum. First and foremost it is used to make sugar. The world production of sugar is about 180 million tons per year and cane sugar represents about 80% of the total sugar market, and about 20% for sugar beet. It is however a sector in structural crisis.
Countries such as Brazil, India or China have planted millions of hectares of sugar cane and are producing at a very low rate, which is driving down prices. Prices have recently been liberalized in Europe. In the coming years, we should therefore witness a new phenomenon of concentration of sugar factories, or even the disappearance of sugar factories in some countries unable to fight against such giants … which could also jeopardize some distilleries of molasses rum that are attached to them.
Unless they opt for pure cane juice or syrup rum, which represent less than 5% of current production, compared to more than 95% for rum made from molasses and therefore from the sugar industry.
The fuel of the future?
Sugar cane is also used to manufacture ethanol and therefore fuel. According to a study by the International Energy Agency (IEA) on the future demand for diesel and gasoline in the world, the global production of ethanol should increase from 120 billion liters in 2017 to 131 billion liters by 2027, while the global production of biodiesel, should increase from 36 billion liters in 2017, to 39 billion liters by 2027.
World biodiesel and ethanol prices are expected to decline by 14% and 8% respectively in real terms over the next ten years. However, a large proportion of agrofuels are made from sugarcane, particularly in Brazil, but also in India and certain African countries. The manufacturing process is quite similar to that of rum: sugar cane is crushed to extract a juice that is then cooked. It is then subjected to hydrolysis, before cooling and fermenting. Then comes the stage of distillation and transformation into alcohol.
As is often the case with cane, nothing is lost and the bagasse is used in boilers. The problem is that in order to plant cane, we deforest, and in order for the ethanol to become a fuel, we add unleaded gasoline to it. So the name “green fuel” or “biofuel” is often usurped, and that is why we prefer to speak of agrofuel.
Electricity and amendments
We have already seen in a previous issue that bagasse (the dry matter that remains once the cane is crushed) is also used to fuel the boilers of rum and sugar producers. The ashes obtained after burning the bagasse in boilers can also be used as a soil amendment in agriculture.
It is often re-injected into sugarcane plantations, as well as vinasse (the liquid residue left over from distillation) or skimmings (residues from the purification of sugarcane juice). Knowing that a ton of cane arriving at the factory produces about 300 kg of molasses which, if distilled, produces 114 L of vinasse.
The bagasse can also be used as mulch in the cane fields to protect the soil. It can also be used directly to produce electricity for businesses and individuals. One ton of cane produces about 300 kg of bagasse which has a calorific value of 7,900 kilojoules per kilogram when burned, compared to 16,000 kJ/kg for dry wood. It is therefore a little less efficient in terms of energy but much more quickly renewed!
Lego and corks from sugar cane
But sugar cane has many other uses. Some blocks of the famous toy brand Lego are now made from sugarcane ethanol transformed into polyethylene. However, they are not yet biodegradable.
The Danish manufacturer had injected 3 billion euros in research of sustainable materials in 2015 and the first biosourced bricks are available in France since last fall. By 2030, the toy manufacturer aims to produce 100% of its bricks from sugar cane.
The manufacturer of closures, Nomacorc (Vinventions group), has launched the Green Line, which produces closures from sugarcane-based polymers called PlantCorc. “Previously, we used oil or natural gas as a raw material to produce our synthetic corks,” explains Stéphane Vidal, Vice President Brand Management & Oenology at Vinventions. Now, everything starts with sugarcane.
Following the production of sugar, the molasses is recovered and then distilled like rum. This alcohol is then transformed into ethylene and then into polyethylene. This represents between 60 and 80% of the material found in the corks. This does not mean that they are biodegradable, but that they are biosourced, because they come from a natural and renewable material, sugar cane.
“This allows us to be certified 3 stars by TÜV, an Austrian organization specializing in biosourced certification”, says Stéphane Vidal. “The other big advantage for us is that we can demonstrate that we have a negative carbon footprint.” The sugarcane alcohol used to produce the corks comes from Brazil. Of the 2.3 billion corks produced each year by Vinventions, about 1.7 billion come from sugarcane, so more than 80%. “We have not come full circle, these corks are not used to cap rum bottles but wine bottles,” says Stéphane Vidal.
Another residue of the rum industry is the sugar cane waxes, the white residues that land in the vinasse or the sludge. Once extracted, they can be used in the composition of medicines to reduce cholesterol levels. In a less positive register for health, rum is used in the manufacture of cigarette papers flavored … with rum!
Finally, it is possible to make “bioplastic” from cane straw and thus produce a host of objects usually made of plastic, such as biodegradable shopping bags or… bottles.