Mixing it Up

Wind-solar hybrids and round-the-clock power could help overcome grid constraints

India is a country rich in renewable energy resources that can be utilised for power generation. While a large part of the country receives high solar irradiation, some states have favourable wind spee­ds. The intermittency issues associated with solar and wind power generation and the limited hours of availability pose problems in grid integration. To overcome the­se issues and combine the benefits of bo­th sources, there is an emerging interest in wind-solar hybrids. Wind turbines and so­lar panels can be co-located at good wind sites to result in a higher comb­ined utilisation of renewable energy. Rou­nd-the-clock (RTC) power is also being ex­plored by bundling renewable generation with other balancing sources such as thermal power and energy storage.

Renewable energy projects often witness variability in power generation and grid stability. It has been established that hy­brid renewable energy systems can re­du­ce this variability, and allow optimal and efficient utilisation of the transmission in­frastructure and land. Thus, there have been several developments in the Indian renewable sector on this front.

A look at the key developments, upcoming projects and future outlook for the segment…

Wind-solar hybrids

The wind-solar segment has been evolving and progressing fast. So far, more than 14.7 GW of wind-solar hybrid (WSH) and RTC capacity has been tendered in the Indian market, of which more than 10.4 GW has been allocated. Of the tend­e­r­ed capacity, 11.8 GW is for WSH, of whi­ch 7.5 GW has been allocated and is ex­pected to come online by 2023.

To support the development of the segment, the Ministry of New and Renew­able Energy (MNRE) released the Natio­nal Wind-Solar Hybrid Policy in May 2018. The policy provides a framework for the promotion of large-scale wind-so­lar hy­brid projects. As per the policy, the­se projects may be used as captive plan­ts, for sale to third parties through open access, and for sale to discoms through competitive bidding or at the average po­wer purchase cost under the renewable energy certificate mechanism. In addition to the national policy, states such as Andhra Pradesh and Gujarat came out with state-level policies for WSHs in 2018. Rajasthan also released a wind-so­lar hybrid policy in 2019 along with its wind power policy. Other states with a pro­mising wind and solar power potential are also contemplating dedicated po­li­ci­es for WSHs.

The overall output from renewable energy projects can be enhanced with the help of complementary generation patterns of wind and solar, along with storage faciliti­es. To this end, guidelines for the procu­re­­me­nt of wind-solar hybrid power throu­gh the tariff-based competitive bidding (TBCB) pro­cess were issued in October 2020. The gui­delines provide a framework for the procurement of power from hybrid projects through a transparent bidding pro­cess. In a notification issued in August 2021 by the MNRE, the guidelines for TBCB for power procurement from grid-connected WSH projects were amended. The amended guidelines are geared to­war­ds addressing issues in implementing large hybrid projects and encouraging in­vestments. They allow discoms to directly procure power from hybrid power generators. This provision will help discoms procure power at a lower tariff by omitting the trading margin to be paid to the Solar En­ergy Corporation of India (SECI).

SECI has been an active entity in tendering hybrid renewable capacity for development. Since 2018, SECI has tendered five tranches of interstate transmission system (ISTS)-connected WSH projects, of which four have been con­cluded. Both Tranche I and Tranche II were undersubscribed, primarily due to low tariff caps in the tenders. The tariffs discovered for the first two tran­ches ra­n­ged from Rs 2.67 to Rs 2.69 per kWh. The tariffs have since been falling, with the low­est discovered rate for Tranche III be­ing Rs 2.42 per kWh and the recently concluded auction for Tr­an­che IV resulting in a new low of Rs 2.34 per kWh. The fifth and most recent tranche of 1,200 MW was issued in October 2021.

Among the innovative tenders, SECI also introduced a 1,200 MW tender in August 2019 for WSH projects with storage to su­pply peak power and another one in March 2020 for 2,500 MW of ISTS-conn­ected blended wind power projects with a wind component of at least 80 per cent. Other than SECI, state agencies, various utilities and companies have also come up with hybrid tenders. These include Ad­a­ni Electricity, Tata Power, and Mahara­s­htra State Electricity Distribution Company Limited (MSEDCL). In addition to competitive tenders, one of the largest hybrid projects currently in the pipeline is the Gujarat Hybrid Renewable Energy Park located near Vighakot village in Kut­ch district of Gujarat. Spread over an area of 72,600 he­ctares, it is expected to have a capacity of 30 GW comprising both solar and wi­nd power. The state government has re­portedly allocated land to Ad­ani Green En­ergy, Sarjan Realities (Suzlon), NTPC, the Gujarat Industries Power Company and the Gujarat State Electricity Corpo­ra­tion for the development of projects in this mega renewable energy park.

Round-the-clock power

Given the increasing demand for RTC power with higher CUFs, SECI has been de­veloping various types of hybrid renewable tenders to make renewable power more despatchable. It issued its first re­newable energy tender with a storage com­ponent in August 2019 and the first RTC tender in October 2019. The initial au­ctions concluded with competitive tariffs. In May 2020, ReNew Power won the SECI auction for 400 MW of RTC power at a tariff of Rs 2.90 per kWh.

In March 2020, SECI issued a request for selection of renewable energy developers for the supply of 5 GW of RTC power fr­om renewables bundled with thermal energy. Under this tender, bidders would quote a composite single tariff for renewable en­ergy complemented with thermal energy. Further, in July 2020, the Ministry of Po­wer released the “Guidelines for tariff-based competitive bidding process for procurement of round-the-clock power from grid-connected renewable energy po­wer projects, complemented with pow­er from coal-based thermal power projects”. La­ter, in November 2020, the ministry amen­ded the guidelines for tariff-based competitive bidding for RTC power projects, adding the provision that renewable projects be bundled with any non-renewable source of energy rather than just thermal power.

This tender was amended a few times, changing the total tendered capacity and reducing it to 2.5 GW from the initial 5 GW. The auction was finally concluded in Oc­to­ber 2021 with Hindustan Thermal Pro­jects, Greenko Energies, ReNew Sa­mir Urja, Power Mech Projects and JSW New Energy being declared the winners. The lowest tariff discovered in the auction was Rs 3.01 per kWh, which is a favour­ably low tariff for bundled power. So far, around 2.9 GW of RTC capacity has been tende­red and allocated by SECI through competitive bidding.

Combining thermal power with renewable generation and energy storage is expected to improve grid balancing. By bundling ch­eaper renewables with expensive thermal power to supply power “round the clo­ck”, a firm supply of power can be achiev­ed to be­nefit discoms as well as developers.

Outlook

Under the national policy for WSHs, the government had set a target of setting up 10 GW of WSH capacity by 2022. While this seems like a tall target to achieve, if development speeds up, it may be possible to reach the goal – or at least reduce the gap. However, there are significant ch­a­llenges to overcome. The cost of hybrid power projects is still relatively high, which the low tariffs may not be able to cover. Additionally, bundling with thermal power or adding a storage component increases the levellised cost.

The situation may become more favou­rable in the coming years when the technology costs of energy storage fall further. With advancements in technology to improve capacity utilisation and lower co­sts, hybrid power projects are expected to usher in a new era of reliable and aff­or­dable renewable power. An increasing sha­re of cost-competitive but intermittent renewable power in the electricity supply mix warrants the deployment of a combination of renewable energy technologies, along with energy storage. Such a mix could be an apt solution for ensuring the stability of the power grid.

By Meghaa Gangahar

 

 

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