C40 Cities releases interim results from Latin America Hybrid & Electric Bus Test; renewable diesel evaluated as well
The C40 Cities Climate Leadership Group (C40) has released interim results from its Hybrid & Electric Bus Test Program, developed in partnership with the Clinton Climate Initiative, and supported by the Inter-American Development Bank (IADB). The results come from test segments run in Rio de Janeiro and São Paulo; additional segments will take place there in Q2 and Q3 2012. In Bogotá and Curitiba, new segments will take place in Q2 and Q3 2012. Participating bus companies include Eletrabus, Volvo Bus Corporation, TATSA, and BYD.
The transportation sector is the largest and fastest growing source of greenhouse gas emissions (GHG) in Latin American cities. Road transportation accounts for 90% of transportation emissions in Latin America, half of which are produced by passenger traffic. The C40-CCI Latin America Hybrid & Electric Bus Test Program aims to reduce the carbon footprint of public transportation in the region through three steps:
Testing bus technology performance in city-specific driving conditions and duty cycles, with specific attention to bus operating costs and to the emission of local air pollutants and greenhouse gases;
Establishing the case for investment in hybrid and electric buses by bus technology companies, cities, and local transport operators; and
Compiling and sharing results among participants and interested parties to stimulate uptake of hybrid and electric buses;
In the test, the environmental performance and economic benefits of approximately 10 hybrid and all-electric buses from several manufacturers are being tested in C40 Cities participating in the program. The buses are being tested under real traffic conditions, in city centers and Bus Rapid Transit (BRT) lines.
In Rio de Janeiro and São Paulo, the Program tested a fleet of four buses—two hybrid and two diesel—each from a different bus manufacturer. After completing the test protocol using conventional diesel fuel, one of the hybrid buses was also tested with a renewable diesel fuel derived from sugarcane.
The vehicles were tested under a wide range of driving conditions on streets that were representative of the respective cities. Emissions measurement was conducted primarily on street circuits at least 15 kilometers (9.3 miles) in length and at least 25 minutes in duration during the non-rush hour period of the day. The buses were tested with a load equivalent to the passenger capacity of the bus. Passenger pick-up and drop-off was simulated during the test runs following a representative pattern of local transit. A minimum of 10 repetitions was normally conducted for each bus. Emissions data was collected with an on-board real-time portable emissions measurement systems (PEMS).
Real-time fuel flow metering was used to obtain precise consumption; data was cross-checked with fuel consumption indicators from the bus electronics. Emissions results were also used to calculate and compare fuel consumption to check consistency.
Second-by-second operating parameters were documented during the tests. Such data can be used in conjunction with Vehicle Specific Power (VSP) methodology to generate emissions profiles from the full range of driving patterns that might be found in a given city. Initial Findings
Initial findings from the Rio de Janeiro and São Paulo campaigns yielded a range of performance results across the various buses and propulsion systems:
The hybrid buses proved to be more fuel efficient than conventional diesel buses, showing reductions in fuel consumption in kilometer per liter of 21.4% to 44.1%.
The parallel hybrid bus system outperformed the rest of the field in all categories.
The tests using sugarcane-derived renewable diesel showed fuel efficiency that was essentially identical to that of conventional diesel on an energy-equivalent basis (km per MJ).
The parallel hybrid buses produced fewer local air pollutants vs. conventional diesel.
C40 is signing new agreements with three additional suppliers interested in participating in the Program. These suppliers would join the current partners in the scheduled campaigns in Bogotá, Rio de Janeiro, São Paulo and Curitiba. In parallel, the Program will lead a strategy formulation exercise starting in April 2012 that will address how the Latin American market for hybrid and electric buses can be developed over the next five years.
A final report aggregating all results will be published upon completion of all phases of work.