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More sustainable buses

A Brazilian company launches a cleaner hybrid electric vehicle in line with a trend among multinational manufacturers

Dual-Bus: works as a trolleybus or electric or hybrid bus that runs on batteries recharged by a small diesel engine

Eduardo CesarDual-Bus: works as a trolleybus or electric or hybrid bus that runs on batteries recharged by a small diesel engineEduardo Cesar

A flexible and environmentally advantageous transportation technology has been in operation in Greater São Paulo since mid-October 2015. This is the Dual-Bus, a hybrid electric bus manufactured by Electra, a 100% Brazilian owned company, headquartered in São Bernardo do Campo (metropolitan São Paulo). Hybrid vehicles use two power sources—a diesel generator and a battery bank—and are far less polluting than buses powered exclusively by fossil fuels. The advantage of the Dual-Bus is its versatility; it is capable of operating not only as a trolleybus connected to an aerial electric grid but also as a purely electric vehicle powered by batteries fed by a diesel generator. It does not need to be connected to an outlet for recharging. The Dual-Bus is the first bus of its kind produced in Brazil. Other manufacturers, such as the Swedish company Volvo and the Chinese manufacturer BYD are also investing in Brazil in new urban passenger transportation technologies based on electric traction. Both also use rechargeable batteries.

“The possibility of the same bus operating as a hybrid, trolleybus or purely electric vehicle brings several benefits to the operation, because the same fleet can meet the needs of various systems,” says Paulino Fumio Hiratsuka an engineer and Eletra’s engineering, development and product manager. “Furthermore, the energy matrix can be modified according to the evolution of generation and storage technology or even the costs involved.” He notes that the Dual-Bus can be used on any line initially as a trolleybus, then continue on as a hybrid—by activating the generator, which is a smaller engine than a traditional one, and the battery bank—and finish the route operating as an electric vehicle, with no polluting emissions. In the event of a power failure, a trolleybus can disconnect from the overhead line and continue on for a few kilometers with batteries. A key on the control panel allows the operator to choose the vehicle’s mode of operation.

“Buses such as Eletra’s Dual-Bus are ideal for large city centers, where worry about the level of pollutants is constant. These sustainable mobility technologies are gaining ground in the public passenger transportation sector,” says Wanderlei Marinho, an engineer and member of the Electric and Hybrid Vehicles Committee of the Society of Mobility Engineers (SAE) and a graduate professor of Automotive Engineering at the Mauá Institute of Technology located in São Caetano do Sul (metropolitan São Paulo). The Dual-bus operates in the ABD Metropolitan Corridor, a roadway in Greater São Paulo dedicated exclusively to buses and trolleybuses. Stretching for 33 km, the corridor connects the São Mateus neighborhood in the east to Jabaquara in the south, crossing the municipalities of Mauá, Santo André, São Bernardo do Campo and Diadema.

Double-decker bus launched in 2015 in London by China’s BYD. The company is opening a plant in Campinas (São Paulo State)

BYD Double-decker bus launched in 2015 in London by China’s BYD. The company is opening a plant in Campinas (São Paulo State)BYD

Electric traction
Only an electric engine drives the model developed by Eletra, and its power comes from a battery bank and a generator engine—this combination also recharges the vehicle’s batteries. This hybrid electric vehicle model works with two energy sources (a generator engine and batteries) operating simultaneously. Since the generator engine is only used for energy production (not to drive the bus), it is smaller than a conventional diesel engine. The result is a 95% reduction in pollutants emitted as compared to a regular diesel-powered bus.

Another noteworthy feature of Eletra’s new model according to Hiratsuka is that it does not require investments in charging stations where the batteries would be recharged. “When operating as a hybrid or electric vehicle, batteries are also recharged when braking through a system known as a kinetic energy recovery system (KERS),”says Hiratsuka. When the brake is applied, the electric engine becomes a generator, and the energy that would normally be wasted in braking is reused and stored in the battery bank. The bus can run up to 20 kilometers as a purely electric vehicle, using only battery power.

With a capacity for 153 passengers, the Dual-Bus is 23 meters long; its four-axle articulated chassis is manufactured by Mercedes-Benz. The electric engine was developed by WEG, located in the southeastern state of Santa Catarina. The generator engine, in turn, combines a Mercedes-Benz diesel-powered vehicular engine and a generator also made ​​by WEG. According to Eletra’s sales manager, Iêda Maria Alves de Oliveira, the Dual-Bus costs 35% more than a similar diesel bus, but maintenance costs are about one-third less. Eletra has been a presence in the Brazilian market for 30 years, where it specializes in the manufacture of trolley, electric and hybrid buses. In 1999, the company introduced the first hybrid electric bus with Brazilian technology (see Pesquisa FAPESP Issue nº 92). Today, about 320 of Eletra’s electric buses operate in Greater São Paulo and another 82 in cities outside Brazil, such as Rosario, Argentina, with 20 vehicles, and Wellington, New Zealand, with 62.

The Volvo hybrid manufactured in Brazil has two engines, one electric and one diesel

Volvo BusesThe Volvo hybrid manufactured in Brazil has two engines, one electric and one dieselVolvo Buses

Swedish electrics
One of the world’s leading manufacturers of buses, Volvo Buses, is also investing in vehicles with low or zero pollutant emissions. Its portfolio of public passenger transport solutions includes versions of hybrid electric, electric and hybrid buses (electric engine, diesel engine and electric batteries). Only the last of the three is produced in Brazil. In 2012, two years after the global launch of the hybrid, the Curitiba unit, located in Paraná State, was the first to build the model outside Europe. With a capacity of 100 passengers, the Volvo hybrid uses the two-engine technology, one diesel and one electric, operating independently. More than 400 units of the vehicle have already been produced in Brazil. They are running in Curitiba, Foz do Iguaçu, Campinas and Sorocaba and have been exported to Bogotá, Colombia. Worldwide, there are more than 2,000 of these vehicles in service in 21 countries.

“Our model uses an electric engine to start the bus and push it up to about 20 kilometers per hour. When it reaches this speed, the diesel engine takes over,” says Idam Stival, Volvo’s sales engineering coordinator in Brazil. “When the vehicle stops in traffic, at bus stops or traffic lights, the diesel engine turns off. Our vehicle operates 20% of the time in electrical mode and 80% in diesel mode. “According to Stival, the Volvo hybrid consumes up to 35% less fuel, therefore emitting 35% less carbon dioxide. In one year of operation, the vehicle prevents 33 tons of CO2 from being emitted into the atmosphere, compared to diesel buses with the same passenger capacity. “Although the technology was developed outside Brazil, the model operating in Brazil has been tropicalized and meets the local content rules for funding by the Brazilian Development Bank (BNDES),” says Renan Shepanski of the sales engineering department.

A year ago, Volvo began to sell in Europe its first hybrid electric bus model. Unlike the version manufactured by Eletra, the vehicle uses plug-in technology, which enables fast recharging at points of passenger entry and departure by means of a connector attached to a kind of post that can be connected to an adapter on the roof of the bus. It is thus able to run 70% of the time in electric mode, using only battery power, and the remaining 30% in hybrid mode using diesel power. The result is reduced fuel consumption and up to 70% less carbon dioxide emissions, compared to conventional diesel buses. By receiving quick recharges, it gains greater operating autonomy when in electric mode.

“The Volvo hybrid electric is a system that works well, but it requires investment and intervention in road infrastructure for the installation of battery recharging stations,” says Marinho of SAE. According to Volvo, its hybrid electric is suitable for longer routes with fewer stops, such as corridors reserved exclusively for buses.

Option in Europe: quick recharging of batteries at points of passenger entry or departure

Volvo BusesOption in Europe: quick recharging of batteries at points of passenger entry or departure Volvo Buses

Chinese electrics
Another company that has begun to produce environmentally sustainable buses in Brazil is China’s BYD (Build Your Dreams). The plant producing the company’s electric buses was christened in August in Campinas (São Paulo State). BYD is one of the world’s largest manufacturers of rechargeable batteries and electric buses. In 2015, the company introduced an electric double-decker bus in London, England. It plans to spend US$400 million on three plants in Brazil by 2018. The Campinas plant will have the capacity to produce between 500 and 1,000 buses per year.

Through an agreement with SP-Trans, the authority responsible for public transport management in the state capital, BYD in September began the first performance testing phase of the K11 model. It is designed to operate in exclusive bus lanes and has a range of 260 km and a capacity of 120 passengers. “BYD has sold electric buses and vehicles in more than 150 cities in 45 countries and we are finding that in addition to the environmental benefits, the electric buses are operating at a cost that is similar or lower than conventional diesel vehicles,” says Adalberto Maluf, director of government relations for BYD.