SIEMENS

Most people in the southern Brazilian metropolis of São Paulo hardly even notice the smog that covers their city every day. The haze seems to belong to São Paulo the way samba belongs to Brazil. But Paulo Costa, who works in Jundiai, some 60 km north of São Paulo, as a sales and marketing manager for Siemens Industrial Steam Turbines, isn't willing to get used to the pollution. When Costa travels to the city, he helps to ensure that the smog doesn't increase — by driving a flex-fuel vehicle, which he switched to several years ago. Numerous studies suggest that such cars emit fewer pollutants than conventional gasoline-powered vehicles.

"If the millions of cars creeping along the city's highways every day were all burning gasoline, the air quality in São Paulo would likely be far worse," says Costa. More and more Brazilians are now switching to highly efficient flex-fuel vehicles that run on a mixture of alcohol and gasoline. Some of these cars can even be driven on pure ethanol, which costs less than gasoline. The CO₂ balance of flexible engines is especially favorable in Brazil, where ethanol biofuel is made from sugar cane — and the amount of CO₂ released when it is burned is equivalent to the amount absorbed through photosynthesis before harvesting.

"Ethanol already accounts for 50 % of the fuel burned in motor vehicles in Brazil," says Costa, "and this proportion is about to increase further." One factor that makes the fuel attractive is the fact that the energy stored in ethanol ultimately comes from the sun. Still, people sometimes forget that the production of ethanol also requires energy, but that much of this energy can eventually be gained from the sugar cane as well. Use of more efficient processes can minimize the amount of energy needed here, however, and technology from Siemens is helping to do just that.

"When Brazil launched its ethanol program in 1975, the sugar mills that produced the alcohol would just burn the fibrous residue of the crushed sugar cane stalks behind their plants," Costa recalls. "But this material — the bagasse — also contains a lot of energy." That's why biomass power plants with outputs ranging between 25 and 70 MW now use bagasse to generate electricity and steam for other industrial processes. As a result, the absolute energy yield per sugar mill has risen about tenfold over the last ten years.

Brazilian companies are very specific about what they want from the turbines they use in their biomass plants. "Our customers are generally price-sensitive, Costa explains. "That means that the trade-off between the cost of the initial investment and efficiency gains over the lifetime of the equipment is slightly different in this particular market."

In response, Siemens has adapted one of its successful European turbine models to the requirements of the Brazilian market, creating a new version of the SST300 steam pressure turbine. "A team of Siemens engineers working in Germany and Brazil spent months altering the model to ensure that the specific demands of Brazilian customers could be met more effectively, and that the unit could be manufactured using materials and facilities available in Brazil," Costa explains. No compromises were made in terms of quality and safety, of course. But the price tag for the modified turbine is around 30 % lower than the original model, making it more affordable for sugar mills throughout Brazil. For example, the design of the extraction valve was modified in order to reach higher pressures of up to 32 bar. And the unit's compact size substantially reduces costs.

Such benefits appeal to Marcos Monaco, industrial director of the Usina Santa Cruz sugar mill. "Our decision to buy the turbines from Siemens was based on the performance and availability of the equipment, which met our project specifications and conditions to the extent that we ordered three units," he says. Usina Santa Cruz is one of 25 major sugar mills that operate in Brazil. Usina's high production volume (some four million tons of sugar cane are processed after each harvest) ensures a considerable competitive edge in terms of efficiency — a key consideration because competition in the industry has become much more intense over the last few years.

What's more, the precipitous drop in crude oil prices in recent months has made it all the more difficult to produce competitively-priced ethanol made from sugar cane. "But," says Costa, "by improving our efficiency, Siemens' turbines are helping us survive in this challenging environment."

Word has gotten around about the advantages offered by the turbines, which is why they are now being installed in other Latin American countries, including Peru, Argentina, Colombia, and Mexico. This new development ensures that even more energy from the sun will now find its way into automobile fuel tanks.