Urban rail transport provides the ticket to a greener future
Transport accounts for around a quarter of energy-related carbon dioxide emissions across the globe and with a global population likely to reach 10 billion by 2050 and with more than a billion more people expected to live in cities by 2030, the levels of transport-related CO2 emissions is likely to increase, unless CO2 emissions per passenger kilometer can be reduced.
Drilling through the data, road users worldwide account for about 71 percent of all transport related CO2 emissions, with 14.3 percent coming from shipping, 12.3 percent from aviation and less than 1.8 percent coming from railways(1).
Currently, even when you include the CO2 emissions from infrastructure, fuel production and the supply chain, on average rail still has a lower carbon footprint than road travel, comparing life-cycle to life-cycle. But with European Union emissions regulations requiring no more than 95grams CO2 emission per passenger kilometer for cars by 2020 (2), it is becoming less clear which, road or rail, is passenger-for-passenger more eco-friendly. This is why as a train operator, you must gather the low hanging fruit, and reduce the CO2 per passenger kilometer emissions, before the eco-transport argument is lost to the car.
By improving the existing rail infrastructure much more can be done to increase the capacity, improve the efficiency and reduce current emissions. Today only about 40 percent of all rail tracks in the world are electrified. The CO2 emissions from diesel trains are not very different per passenger kilometer to a modern small car and now that fully electric vehicles are available, the benefits of electric vehicle over diesel trains are clear. When comparing modern electric trains with electric cars the story is quite different – a Tesla Model 3 consumes 14.73kWh/100km(3), that is 36.83Wh/km per seat; taking an average European occupancy of 1.2 passengers per car, we get 122.75Wh/passenger km, whereas a modern electric train consumes 30-31Wh/km per seat(4), or 50-52 Wh/km per passenger. In terms of Wh per passenger, it is clear that the modern train can already outcompete the electric car.
Additionally, technology such as braking energy, can create dramatic savings in energy consumption and help reduce emission still further, with as much as 41.6 percent recovery of total energy consumed. Historically, breaking energy has been lost and dissipated as heat. In subways, this heat has been removed by heavy-duty ventilation systems, which not only affects the cost of the infrastructure, but adds to the power consumption and emissions of the system.
Price pressure on operating costs have generated increasing demand for better energy management and recycling braking energy is a part of that equation. Today it is quite common to have energy management as an integral part of new metro systems, for example, but it could also play a role in older existing systems. With an energy storage system or energy recuperation system, the energy consumption of the train decreases considerably, and it also reduces the voltage and power demands on the electrical network. Efficiently optimizing the use of energy with the help of energy storage systems can reduce the overall power consumption by as much as 30 percent, therefore contributing to make the system even more energy efficient, helping to reduce the Wh/km per passenger still further.
Although the car will get greener, so too will the train. Now is the time to electrify and replace diesel and invest in energy management as an integral part of a railway’s network.
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