Metro going green: Will power its own trains

Inspired from the success story of many, Hyderabad Metro Rail has now taken a leap for being one of the most energy efficient and eco-friendly projects the country has witnessed. Besides giving comfort to commuters at a price which is easy on their pockets, the rolling stock sports some exclusive features which includes the revolutionary ‘Regenerative Braking System’.

Regenerative electric braking converts the momentum into electrical energy and feeding back to the power supply system while braking. As a contribution towards the UN supported CDM (Clean Development Mechanism), this will reduce the energy requirement from the grid. The project, which is seen as a solution to all the traffic related woes in the city, is now capable of generating nearly 30 per cent of its own power consumption. The current cars are designed and are equipped with the technology. Inspired from the success of similar technology in Delhi Metro Rail, manufactured by Bombardier Movia, the HMR authorities were keen on the technology and made sure that Hyundai Rotem had this particular technology in place.

Adapting this technology, the Delhi Metro had became the first railway project in the world to be certified for carbon credits for reducing greenhouse gas emissions, by the United Nations. According to reports in Delhi, the metro service had saved 1,12,500mw of power by using regenerative brakes on trains and reduced carbon emissions by 6,30,000 tonnes yearly. Former Delhi Metro chief E Sreedharan said that use of regenerative braking system in trains — that results in power production — was one project that had been certified for carbon trading and another project had received in-principle approval.

Through the sale of carbon credits over two years as part of the scheme, Delhi Metro received the cumulative remuneration of Rs 2 crore. The initiative also led it to become the first railway project based on regenerative braking to be registered by the United Nations Framework Convention on Climate Change.

With the current scenario, Hyderabad Metro would be in the catalogue of metros across the globe for taking the eco-friendly step. “The trains will be generating 30 per cent of the power using regenerative electric braking where the momentum is converted into electrical energy and the same is fed back to power supply system, while braking. It will also help reduce energy requirement from the grid,” said VB Gadgil CMD, L&T Metro Rail.

It is estimated that 14.5 kw of electricity is required to run the Metro Rail in the Nagole-Mettuguda line and an estimated 4.9 kw of electricity would be generated by the Regenerating Braking System.

The first metro train that was received from South Korea would be put on tracks for test and trials any time on the 8km stretch atop a viaduct.

The trial runs will go on for at least nine months before the Commissioner of Rail Safety certifies it fit to be used for public transportation.

How the system works?

All the wheels of the Metro Rail coaches will have brakes. When they are applied, the frictional energy is converted as electrical energy via a specially designed motor and the electricity is fed to main power supply. The more the number of times brakes are applied the more the electricity generated. The coaches have vacuum, electro-pneumatic and electronically controlled pneumatic brakes and all these are equipped with converters to convert the frictional energy and momentum into electricity. For example: There are seven stages in the Nagole- Mettuguda line and the Metro Rail will halt in all the seven stages. So brakes would be applied seven times. The amount of power generated is directly proportional to speed of the train and the engineers say that if the train is travelling at a speed of 72 kmph, brakes have to be applied 45 metres before the stages, and the frictional energy and the momentum in the 45 metres stretch would be tapped and converted to electricity.