The salt-filled air from sea breeze winds and the sight of a freshly emerging sun in the tiny village of Thirupullani in Tamil Nadu make for a picturesque sight – and a potentially valuable one.

The natural bounties of the village on the shores of the Bay of Bengal, 125 km away from Madurai, hold clues to crucial steps India could take in its renewable energy journey.

Seven years ago, a team of researchers from Madurai’s Thiagarajar College of Engineering chose this village for a feasibility study of a wind-solar hybrid system – one that would generate power by using both photovoltaic cells to produce solar energy and wind turbines.

The sun and wind are intermittent but complementary energy sources. Solar generation peaks during the daytime while power generated by wind sources is high during the twilight and the night. Similarly, during the monsoon, when sunlight is weaker, wind could compensate.

Thirupullani, a village of 6,000 people, with adequate sunlight and wind, was a good site to conduct the study, the team thought.

The findings from the study, conducted between 2012 and 2014, were eye-opening: when wind and solar sources are hybridised, production costs could be cut by half.

The team calculated power output and costs with 725 different combinations by adjusting many variables, such as the price of land, solar panels, turbines, maintenance and energy storage.

Credit: Vasudevan Sridharan.

In Tamil Nadu, it costs about Rs 6 to generate a unit of electricity from a conventional source such as coal. The per-unit cost from solar is about Rs 10 and from wind Rs 7.50 – but from the hybrid model, the team calculated it was Rs 3.50.

Hybrid systems are cost effective because they share the transmission infrastructure such as power lines, transformers and substations. The vast pockets of land between two turbines – which remain vacant mostly – can be used to set up solar panels.

Further, while the maintenance of wind equipment requires skilled labour and sophisticated apparatus, that is not the case with solar. When wind and solar are co-located, the benefits include cost synergies through the sharing of personnel and infrastructure.

“Our Thirupullani case study may not be exactly replicable across Tamil Nadu or India’s landscape but it has enough pointers” to indicate that hybrid models can be successful, said Suresh Kumar, an electrical engineer who led the research team.

Complementary sources

About 150 km from Thirupullani lies India’s energy research cradle of Kayathar, home to Asia’s first wind farm set up in the late 1980s. It is a vast landscape with ever-flowing winds. The flat topography enjoys a steady supply of sunlight too.

At this government-run facility, a solar constituent was added four years ago to supplement wind energy, a steady source between May and September due to seasonal gusts from the Sengottai pass of the Western Ghats.

Here, the hybrid structure works efficiently. But despite the cost-effectiveness of hybrids and the state’s desire for cleaner power, such models remain severely underutilised in Tamil Nadu, thanks to the lack of a focused policy. Tamil Nadu is yet to produce any hybrid power.

India has now created wind-solar hybrid plants with installed capacity of about 1.3 GW, mainly in Gujarat, Rajasthan and Karnataka. As per central government regulations, to be deemed a hybrid facility, at least one-fourth of power output should come from either wind or solar.

Lack of policy framework

Tamil Nadu has been a pioneer among Indian states when it comes to renewable energy. About half of its installed capacity or 17GW is from renewables like wind, solar, hydro and biomass. So, any adoption of newer systems by the southern state will directly benefit the national power situation.

India is the world’s third-largest renewable energy producer after China and the United States. At the United Nations Climate Action Summit in 2019, it set ambitious goals to switch to cleaner energy sources: by 2030, it aims to generate 450 GW from non-fossil sources but is likely to miss the target of 175 GW for this year.

In 2016, Tamil Nadu was expected to be the biggest beneficiary when the central government announced the draft policy to boost the green energy sector through hybrid systems.

However, interviews conducted across the green energy-rich belts in the state and detailed discussions with over two dozen stakeholders indicated that the state has fallen short of its potential – mainly because of the absence of a clear policy.

In 2018, India’s ministry of new and renewable energy’s National Wind-Solar Hybrid Policy in 2018 offered a set of incentives such as smoother procurement of components for renewable energy, waiver of charges on energy production, and sale of electricity to third parties instead of just the government.

Power policies fall under India’s concurrent list, meaning the central government only issues guidelines and the states decide how to implement them.

Shortly after the ministry announced its hybrid policy, states like Gujarat, Andhra Pradesh, and Rajasthan formulated hybrid-specific regulatory frameworks while others like Kerala and Karnataka issued drafts.

Andhra Pradesh is expected to generate 5,000MW of power from hybrid facilities by 2023 while Rajasthan will touch 3,500MW 2024-’25.

Still, Tamil Nadu is nowhere on the scene. “Because of a lack of policy, hybrid is still in limbo in Tamil Nadu,” said Sajay KV, chief executive officer of the Indian arm of BrightNight, a US-based renewable energy firm. “We tried for five-six years and somehow there is no vision.”

An absence of a coherent policy means that if wind energy suppliers want to add solar components to the existing facility, they have to obtain additional permissions, a cumbersome and expensive process.

Sajay helped build India’s first commercially successful wind-solar hybrid power plant in the neighbouring state of Karnataka in collaboration with the government and the plant was commissioned in 2018.

“Someone has to take initiative,” he said. “This is like having a coal mine but mining only 50% of its capacity. The national resource is going to waste. It’s a loss to the state exchequer.”

S Gomathinayagam, an independent consultant, said that Tamil Nadu could “greatly benefit from wind-solar hybrids at GW level, MW level as well as microgrids with 100s of kW level”.

When he was director general of the Chennai-headquartered National Institute of Wind Energy, a central government-run research think tank in 2016, he led a detailed analysis of the hybrid system in Tamil Nadu.

The state is missing a “golden opportunity” by not capitalising on the hybrid model, he said.

“The hybrid power in the grid would relieve the load demand by households and agricultural demands in the grid making less costly power to attract industrial development and green investments,” said Gomathinayagam. “If there is enough socio-political will, there is no dearth of renewable energy power. RE [renewable energy] hybrids with REs could take Tamil Nadu into a total green-powered state in India.”

A detailed economic viability analysis by JMK Research on Tamil Nadu’s energy architecture showed that a hypothetical hybrid renewable energy storage system would cost Rs 3.4/kWh by 2030 as against coal-generated power, which is at Rs 4.5-6/kWh.

This echoes the findings of the Thirupullani case study.

However, despite a wealth of data suggesting the potential of the wind-solar hybrid model, Thirupullani remains a sleepy little town filled with favourable winds and sunshine that could be captured for energy generation – but aren’t.

Despite repeated requests, Tamil Nadu’s energy minister and his representatives declined to answer any questions for over two months. A detailed questionnaire with specifics remains unanswered.

Vasudevan Sridharan is an independent journalist based in South India.

This story was produced with the support of Internews’ Earth Journalism Network.