The Hindu : New Delhi News : Metro saving energy in a big way

Online edition of India's National Newspaper
Sunday, Dec 23, 2007
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New Delhi

New Delhi

Metro saving energy in a big way

Smriti Kak Ramachandran

Restricts power consumption to 1.2 per cent of the city’s total requirement

Many energy-saving practices used
Attention paid to the station designs , power usage in underground stations

NEW DELHI: The Delhi Metro Rail Corporation (DMRC), which consumes about 70 per cent of all the steel and cement used for construction in the Capital, has set an example by conserving energy and restricting its power consumption to a mere 1.2 per cent of the city’s total requirement.

The DMRC with its expansive network has been able to put a ceiling on its energy consumption by switching over to energy-saving practices. According to officials at the Corporation, through the use of various technological interventions the power requirement has been “restricted” to just 45 MW.

“The DMRC has adopted many energy-saving practices to ensure that the energy consumption is kept at a minimum,” said its spokesperson Anuj Dayal.

Listing the energy-saving practices, he said: “We use insulated gate bipolar transistor (IGBT)-based variable voltage variable frequency drives (VVVF) for our trains to help reduce power consumption during starting and stopping of trains.”

“VVVF enables regenerating braking in trains, which saves about 30 per cent of energy consumption,” he said, adding that “the lighter weight of the coaches of the Metro also ensures less consumption of energy.”

The official said attention had been paid to the station designs as well. The stations are designed on a “hump” to ensure faster acceleration after start and faster deceleration while stopping.

“Air-conditioning and ventilation systems of the stations have been optimally designed. Energy-efficient equipment has been used for running the air-conditioning and ventilation systems and sky lights have been installed in the underground stations to ensure maximum use of daylight,” said Mr. Dayal.

In the underground stations, where more power is required to provide light and run the systems, the lighting system has also been so designed that every fourth light can be switched off with a single switch. This has been done to ensure a control on power consumption.

“The dimming system on Line III ensures reduction of power as per daylight conditions. Variable voltage and variable frequency drives (VVVF) in lifts and escalator match the power requirement as per actual load. This also saves 30 per cent of energy when escalators run without passengers,” he said.

The escalators too have been designed to reduce their speed when not in use. This brings down the consumption of energy by about 30 per cent.

“Water pumps have a level control system that helps in automatically switching off the pump after a certain level of water filling. A circulating area and entry lighting for the underground sections have been provided with separate lighting control system, which can be switched off during daytime and tunnel lights are put off during the day.”

To ensure an uninterrupted supply of power for the Metro, which maintains its own sub-stations, electricity for each line is drawn from a minimum of two sources and power is also procured from a double circuit out of which only one is used at a time.

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