Kolkata Metro turns to Non-Conventional Sources of Energy to cut down Costs

Kolkata MetroKolkata: With its electricity bill responsible for nearly 15% of the annual ordinary working expenses, Metro Railway is turning to non-conventional sources of power to bring down costs. After Mumbai, Kolkata is the most expensive, so far as power tariff charged from the metro is concerned. Metro Railway purchases power from CESC at Rs 7.20 per unit and consumes 300,000 units per day. While the Mumbai metro pays Rs 8.91 per unit, the rates are Rs 6.10 and Rs 4.80 in Delhi and Bengaluru respectively. One of the reasons for the metro’s proposing a fare restructuring is the high cost of power in Kolkata.

“We are taking several initiatives to ‘Go Green’. While we have started tapping solar energy wherever possible, we are also introducing more efficient equipment to conserve energy. The idea is to bring down expenses and protect the environment. Metro is eco-friendly as it doesn’t use fossil fuel directly but power plants do. As there is shortage of space, the emphasis is on setting up small capacity roof-top solar plants. Two solar plants of of 10 and 20 kWp have already been commissioned. They have generated 3,217 units of power in 2014-15 and brought down costs by Rs 22,183. Two more 10 kWp solar power plants will be commissioned in this financial year. The four plants together will generate 5,500 units resulting in savings of Rs 37,000 annually. This may sound modest but it is a good start,” said Indrani Banerjee, SrPRO, Metro Railway.

In addition to this, larger solar power plants have been planned on roofs. The two 50kWp plants will be installed at Dumdum and Noapara in 2016-17. The metro has also set up a 300 litres/day capacity solar water heater at Noapara carshed. In 2014-15, it saved 3,000 units of power and cut Rs 20,500 from the electricity bill. In this financial year, two more solar water heaters of 500 litres/day capacity each will be commissioned. The three plants will help the metro save 13,000 units of power. The electricity bill is expected to come down by nearly Rs 89,500 after this commissioning.

“We are also procuring energy-efficient equipment. All new rakes will have 3-phase technology and 3-phase induction motors. In existing rakes, DC motors are used. In DC motors, during braking, energy is wasted in the resistors, resulting in loss of energy and generation of heat. Electric braking to very low speed is possible in 3-phase technology, resulting in improvement of operational efficiency and reduction of maintenance efforts as the wear rate of wheel and brake shoes is lower. In 3-phase technology, electrical power can be returned to the third rail during braking. This is known as regenerative technology. Due to improved power factor and regeneration, energy saving to the tune of 20-30% can be expected,” an official said.


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