The São Paulo metropolitan region, with its population of more than 11 million and seven million cars, is among the world’s most polluted cities in term of air quality. It is estimated that thousands annually die from of the effects of air pollution.
Fortunately, the region is taking active steps to reverse this harmful trend. By 2018, the region will ban the use of fossil fuels and the public transport operator SPTrans, with a fleet of 15,000 buses, is planning for a fossil-free future.
The buses are presently operated using conventional diesel, biodiesel and ethanol as well as an electric trolleybus system. Using locally produced biogas offers opportunities to nearly eliminate greenhouse gas emissions as well as other harmful pollutants.
Latest-generation gas buses
A high-level delegation from SPTrans recently visited Sweden to learn more about also introducing biogas. They studied biogas production and the experience of public transport operators in deploying large-scale biogas fleets. At Scania, the delegation had the opportunity to test drive the latest-generation Euro 6 gas buses that are now being put into service in Europe.
“Air pollution is a major challenge for us and we haven’t, as of yet, operated gas buses,” says SPTrans’ Operations Director Almir Chiarato Dias. “But in my view, biogas is definitely a fuel for the future.”
Gas buses were tested some 15–20 years ago with disappointing results. Although the buses operated smoothly, the fuel supply chain turned out to be an insurmountable obstacle. Buses are allotted a mere three hours a day at depots for fuelling, washing, cleaning and maintenance. Much of that time was spent in refuelling.
Efficient gas fuelling
Those days are gone and modern-day gas trucks can be efficiently fuelled in just five minutes. “I don’t have the slightest doubt that these buses are right for São Paulo, my only concern is the logistics for servicing buses at our 30 depots.”
Brazil has a growing problem with waste from its large agribusiness sector and Scania is presently trialling a Euro 6 gas bus using biogas generated from poultry and cattle manure in the southern Brazilian city of Foz do Iguaçu. This demonstration confirms that the Scania Euro 6 gas engine is the world’s most energy efficient gas engine to date.
The São Paulo region also, of course, generates huge amounts of waste water that can be gainfully converted to biogas at treatment plants. Collection of organic waste for anaerobic digestion into biogas is another option. It is estimated that the waste from one person alone is sufficient to produce 100 cubic metres of biogas.