Álvaro J. López-López

Energy savings in metro-transit systems: a comparison between operational Italian and Spanish lines

For transportation in large cities, new technologies that impact the operation of metro-transit systems are being developed. The energy efficiency in metro-transit systems is a key topic that is being studied in order to reduce both consumption and costs. A review on approaches to managing the energy recovered from train braking is reported. Then, energy performance indexes are presented. Their assessment is possible due to highly specialized simulation tools that have been developed at the University of Rome Sapienza and Comillas Pontifical University, Madrid. The indexes are used to perform a comparison between an operational metro-line in Spain and one in Italy. The results confirm their accuracy and significant improvements in energy efficiency and environmental effects are presented.

Optimal deployment of energy storage systems in a DC-electrified railway system

Energy Storage Systems (ESSs) represent one of the main vectors for improving railway electrical systems. Former low reliability rates and life-time are being dramatically improved in recent times due to the intensive research on battery and capacitor technologies. However, little research has been conducted on the optimization of railway system infrastructure by incorporating ESSs. This paper presents a method for designing the best possible deployment of ESSs in a DCelectrified mass rapid transport system line by means of optimization, selecting number and location of ESSs. A detailed model of system load flow and energy storage devices for a given traffic scenario in a general DC railway system has been carried out, resulting in a MINLP optimisation model that minimises total energy consumption. Then, a linearization of load flow equations has been performed in order to get a fast-approximate solution of the system by converting the MINLP problem into a MIP one. This optimization method has been applied to a realistic railway system, yielding reasonable location and number of ESSs in the system. The error due to the approximation has been evaluated by comparing the results of the linear load flow against those of the non-linear load flow. The method has demonstrated to be a powerful tool to decide how many and where to place ESSs in a DC-electrified railway system.

A variable no-load voltage scheme for improving energy efficiency in DC-electrified mass transit systems

Railway mass transit systems like subways play a fundamental role in the concept of sustainable cities. In these systems, the amount of passengers strongly fluctuates along the day. Hence, in order ...

Riding the Rails to DC Power Efficiency: Energy efficiency in dc-electrified metropolitan railways.

Energy and environmental sustainability in transportation have become crucial in recent decades. According to the Intergovernmental Panel on Climate Change?s Fifth Assessment Report (AR5), the transport sector accounted for 27% of the final energy use and 6.7 gigatons of CO2 direct emissions in 2010, with baseline CO2 emissions projected to approximately double by 2050. Reductions in total transport CO2 emissions of 15?40% compared to baseline growth could be achieved in 2050. In this context, railway systems are growing steadily more important in developed countries. Their high energy efficiency makes them preferable to other transportation methods, both for passengers and freight. In the case of passengers, they are able to move a large number of people without local emissions, thus reducing pollution. Electrified railway lines also contribute to the use of renewable energy sources.