Tuesday, March 15, 2016

How Much can e-LRTs Reduce Greenhouse Gas Emissions?

Light Rail Transit train on the Dudley B. Menz...
Light Rail Transit train on the Dudley B. Menzies Bridge in Edmonton, Canada (Photo credit: Wikipedia)
The Role of Rail Transit Systems in Reducing Energy and Carbon Dioxide Emissions: The Case of The City of Rio de Janeiro (16 page pdf, Carlos Eduardo Sanches de Andrade  and M├írcio de Almeida D’Agosto, Sustainability, Feb. 5, 2016) 

Today we review a paper that uses a model to estimate the GHG emissions avoided by shifting urban transportation mode from passenger car to electric rail transit as a test case for Rio de Janeiro, Brazil, a city of 6.5M, projected over the period from 2016 to 2040. The amount of GHG emissions avoided were 55,449 tonnes per year for the city or 44.53 grams per passenger kilometer. Although cars in Brazil use more ethanol in their fuel than elsewhere and this is accounted for here, many of the assumptions made to model the shift could be applied to other cities.

 Key Quotes: 

“Rio de Janeiro, Brazil, has established…a goal of reducing greenhouse gas emissions of the transport system by 20% until 2020 compared to 2005. In order to reach this goal, the city’s public transport has been restructured with an emphasis on rail transit systems.” 

 “In Brazil, the energy consumed by the transport sector in 2013 represented 32% of the total energy, with an increase of 5.2% in relation to 2012.The amount of GHG emitted in that year by the transport sector in Brazil reached 215 million tones” 

“The model considers the following elements: (a) Debit: The emission produced by the generation of electricity used by the passenger rail system…. (b) Credit: The emission avoided by the system
  • Mode shift, which represents the gains achieved by the fact that users of private cars and other means of transport causing higher emissions shift their transport mode of choice and use the system, leading to fewer trips with these higher-emission vehicles.
  • Congestion relief, which represents the gains obtained by less traffic congestion due to the smaller number of vehicles on the streets..
  • Land use, which represents the gains obtained by a higher population density.. people need shorter trips and use fewer cars.”
“Tests carried out by the Rio de Janeiro Metro [38] indicated that the average energy consumption of each car varies from 2.97 to 4.80 kWh per kilometer traveled, with the first value representing an empty car and the second value representing the car during peak hours, with 357 passengers"

Passenger rail systems powered by electricity can contribute to the reduction of GHG emissions of the transport system and make it more sustainable. The condition for that result is that the rail system emission per PKM [passenger kilometer) be lower than that of the replaced transport modes.”

 “The net amount of carbon dioxide avoided [from 2016 to 2040] was 55,449 tonnes per year and 44.53 grams per passenger kilometer. The avoided energy reached 0.76 MJ per passenger kilometer.”

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