Wanchoo says this technology is a game changer in terms of reducing the country’s carbon footprint and is ready to be exported to other nations which like India suffer from two limitations—low wind speeds and scarcity of land. Low wind speed nations are those with wind speeds of 6-7 metres a second through the year. In contrast, in Europe it is 10 m/s, while it is 8-9 m/s in most parts of the U.S.

With fossil fuels set to run out in the next 100 years, nations are betting big on green energy. At the Paris Agreement, India committed that 40% of its power capacity would be based on non-fossil fuel sources—which includes nuclear energy and hydropower—by 2030. No surprise then that the government’s subsidy for renewable energy has grown almost sixfold, from ₹2,608 crore in FY14 to ₹15,040 crore in FY17, according to an International Institute for Sustainable Development report on India’s fossil fuels and renewable energy.

Policy support for green energy has also come from the identification and assessment of potential sites through the National Institute of Wind Energy, waiver of interstate transmission charges, and customs duty exemption on certain components of wind electric generators. Recently, minister for power, new and renewable energy R.K. Singh asked the Reserve Bank of India to remove the priority sector lending limit for the renewable energy sector to encourage public sector banks to lend more. Having wind and solar at a single site also makes economic sense for developers because tariffs for renewables have been falling steadily, with wind energy prices touching ₹2.43 per kilowatt-hour (kWh) and solar ₹2.44 per kWh. It remains the cheapest source of energy in the country at less than ₹3 per kWh. “The idea is to ensure the capital cost of setting up the twin projects in a single location should be much lower than setting up separate units in different sites,” says GE South Asia chief technology officer Alok Nanda, who is also CEO of the Bengaluru technology centre. The success of hybrid technology, he argues, has already been proven in several studies and in a couple of pilot projects. “With falling battery prices, it will become the most-preferred option for developers,” says Nanda. ReNew Power chairman and managing director Sumant Sinha agrees. A lot of technological innovations in the past three years have allowed developers like him to generate far more power from the same wind speeds, Sinha says. “And once storage is in place, it really does not matter whether one is using solar or wind energy. But the problem with storage is that it is still very expensive… storage costs have to come down quite substantially for them to become economically usable,” he adds. Storage can either be in the form of a battery or pump storage. While lithium-ion batteries are common, pump storage is possible only in a few countries because it involves pushing stored water up a terrain using solar or wind energy and then releasing it at a time of lower energy generation so that it falls on the wind turbines and rotates them to generate electricity. As Gilan Sabatier, general manager, South Asia & ASEAN, GE Renewable Energy, says, “Storage is probably the last link between having renewables as a part of the energy mix and renewables being the whole of the mix.” Sabatier believes the war on cost has been won because the most expensive renewable power is available at less than ₹3 per unit compared to ₹4.10-₹5 per kWh for thermal power. But others are of the opinion that renewables will become a real game changer when the cost of generating renewable power becomes less than the running cost of thermal power.

Let’s get back to the challenge Nanda’s team faced to evacuate solar and wind energy via a single transmission line. “We developed a common inverter for wind and solar with creative power electronics and innovative model-based controls at turbine and farm level,” he explains.

Such has been the impact of this technology that a separate hybrid renewable division has been created within GE by merging the other verticals of solar, wind, transmission, and grid into a single unit. Running the hybrid plants will require leveraging strengths of all these different verticals, explains Wanchoo, who also has a master’s in computer engineering from the University of Southern California.

The biggest hurdle in commercialisation of hybrid technology is cost. Wanchoo says it isn’t fair to compare the tariffs for hybrid technology with the tariffs for wind or solar power. “A fair comparison should be with base load power or thermal energy, which averages between ₹4 and ₹5 per kWh,” he says.

But even the best hybridisation strategy won’t reduce the importance of continuous improvements in wind and solar energy technologies. And customisation of wind turbines for Indian conditions is already paying dividends. For instance, the plant load factor (PLF) or efficiency of these turbines has already gone up from 20% to 35% in the past three years. “The impact of increased PLF means a 40% cost reduction for developers,” says Sinha. ReNew Power has 4,500 megawatt (MW) of commissioned power, which Sinha wants to double in the next three years.

There are a few structural factors that constrain the growth of wind energy in India. First, there aren’t too many sites which have the required wind strength, and the best ones have already been taken. “Therefore, developers are unlikely to get 100 MW of wind energy from one site in the future,” says Sinha. Compounding the problem is the timely evacuation of power from these sites in the absence of adequate transmission lines and grid connectivity.

Second, the variability and volatility of wind energy is much higher than that of solar energy and therefore predicting the actual output is more difficult than for solar. For instance, the variability of wind energy between two consecutive years can be as much as 10% while that of solar is just 2-3%. “But the biggest challenge with wind energy is that wind speeds pick up the most during the monsoon season when demand is low and hence utilities such as distribution players may not be interested in picking up the extra load,” says Sinha.

Sumant Sinha

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