Handling wind power: TN faces many a challenge

Despite Chief Minister Jayalalithaa’s positive assurances in her statement of May 27, Tamil Nadu is neither a power-cut-free state, nor is the state-owned utility, Tangedco, buying all the electricity the state’s wind power plants are producing.

Even now, 4-5 hours of wind power generation is not being taken, despite there being sufficient transmission infrastructure, says PP Gupta, Managing Director of Techno Electric, whose subsidiary, Simran Wind Project, owns 190 MW of capacity in the state. Officials of Tangedco have long been saying that handling wind power is a problem because of its infirm nature. In tandem with ebbs and flows in wind, the electricity put into the wires surges or falls, it is a problem for the grid manager.

So then, can Tamil Nadu not have more wind power? Wind is cheap and clean, and the state can accommodate a lot more wind power capacity – should the state give it all up because wind power is infirm?

No, say experts. You can handle infirm wind if you have sufficient ‘peaking capacity’, or power plants that can very quickly ramp up generation when required. Fortunately, Tamil Nadu has four such power plants – Basin Bridge (196 MW), Samalpatti (100 MW), Madurai Power (100 MW) and Pillaiperumal Nallur (330 MW).

The problem with these plants is, the power they generate is very expensive – around ₹12 a kWhr – because of the fuel costs. However, in order to have more cheap wind power, the full use of these peaking capacities is inevitable, say experts. “These sources cannot be viewed in terms of their higher cost alone; we need to recognise the role they play in balancing the grid and that should be appropriately valued,” says Santosh Kamath, Partner, Infrastructure & Government Services, KPMG.

Wind industry leaders such as Madhusudan Khemka, Chairman and Managing Director, Regen Powertech Ltd, a leading wind turbine manufacturer, have said that a proper mechanism for forecasting wind is critical. Khemka and Gupta have said that the industry is willing to fund to equip the power router, the state load dispatch centre (SLDC) to forecast wind. If you know how much of wind you will get at a wind farm the next hour, it is possible to ask the peaking capacities to flex up quickly, so that the wind falls, the generation from gas and liquid fuel plants streams in, and the grid balance is maintained.

These capacities can quickly come online. For instance, the GMR-owned Basin Bridge power plant can ramp up from zero to 20 MW at the rate of 2 MW a minute, and from 20 MW to 50 MW at one MW a minute.

Therefore, it would be folly to discard the generation from these peaking plants as costly. “It is over-simplistic and incorrect to evaluate system costs based only on the individual resource costs” says Anish De, CEO of Mercados Energy Markets India Pvt Ltd, a market research firm. “For a secure and economical operation of the power system, the costs of these resources need to be considered and optimised in conjunction.  The operating costs of individual resources are not of particular relevance so long as the overall system costs are optimised,” De told Business Line .  

Incidentally, the Power Purchase Agreement between Tangedco and GMR expired on February 15, and the utility has petitioned the State electricity regulatory commission, TNERC, to extend the agreement by one year. Tangedco officials have not responded to as to why one year. The PPAs of the other two liquid fuel plants are also due to expire shortly. No petition has been made to extend them.

In the absence of peaking capacities, the wind power capacity in the state will continue to be under utilised, experts note.