Sugar to Ethanol Plants make sugar through a process called photosynthesis The plants take in carbon dioxide from the air water from the soil and sunlight They create sugar and oxygen This sugar can easily be turned into ethanol However using plant cellulose the material in plant cell walls is more complicated The material must be treated to break down the plant cell walls into sugar Then the solution can be fermented to ethanol The extra step of breaking down the cellulose makes this type of ethanol more expensive than ethanol made directly from sugar extra step means it takes more energy to make corn ethanol than sugarcane ethanol In addition an acre of sugarcane produces approximately twice as much ethanol as an acre of corn produces 1 However sugarcane does not grow well in most of the United States and the government’s sugar policies make sugarcane ethanol unprofitable for growers As a result corn is a more popular source of US ethanol Most car fuel in the United States contains approximately 10 percent ethanol and 90 percent gasoline This mixture is called E10 It helps reduce the use of gasoline Most vehicles cannot use fuel with more than 27 percent ethanol 2 However some specially designed engines can use more Flexible-fuel vehicles can operate on fuel blends with higher levels of ethanol up to 100 percent in some cases Sugar could replace most gasoline in some parts of the world In Brazil this is already happening Brazil is the largest producer of sugarcane ethanol in the world Approximately half of the cars in Brazil are flexible-fuel vehicles that can use any mixture of gasoline and ethanol 8
The remaining cars can use 18 to 25 percent ethanol 3 Using flexible-fuel vehicles and sugarcane ethanol has reduced pollution in Brazil because ethanol is considered a cleaner fuel than 100 percent gasoline This has been good for the environment while also reducing Brazil’s dependence on oil imports Abel Uchoa a manager at a Brazil sugarcane company says We see ethanol as the fuel of the future whether it’s in Brazil or in the world beyond 4 USING SUGAR WASTE Sugarcane can provide a different type of energy as well The sugarcane stalk has an inner pith that holds most of the sugar The pith is surrounded by a tough outer rind When sugarcane is processed the stalk is crushed to release the sugar The rind and the fibers from the center of the stalk become a waste product called bagasse In the United States sugar mills produce millions of tons of bagasse every year The sugar contains only approximately one-third of the plant’s energy The rest stays in the bagasse In the past bagasse was typically burned in the fields causing pollution Today bagasse is being used in new ways that reduce pollution Bagasse can be burned in a factory to produce steam which can be used to generate power Many sugar mills get their heat and electricity through this process Some sugar and ethanol mills sell their excess electricity to the community In 2012 Brazil got approximately 4 5 percent of its total domestic electricity from bagasse 5 9
Sugarcane processing leaves behind large amounts of bagasse Burning the bagasse releases some carbon dioxide However the amount is equal to the carbon dioxide that was absorbed by the plants as they grew This makes using bagasse for energy carbon neutral The process does not add additional greenhouse gases into the atmosphere the way burning coal or oil does MORE USES FOR BAGASSE Bagasse can also be made into products such as plates and toilet paper These products can replace items usually made from plastics or foams such as Styrofoam Bagasse products can be produced with less energy than these other materials require They biodegrade in approximately 90 days breaking down harmlessly 6 Some studies have shown that using materials such as bagasse for paper products is better for the environment than 11
