Transmission bottleneck in adding the RE capacity

Lack of transmission infrastructure is also being considered another major bottleneck for large-scale deployment of renewable energy sources in India. Large-scale renewables are mostly being deployed on barren land, and these areas are not close to the demand centres, which leads to a lot of projects facing curtailment due to lack of transmission. Typically, the timeline for transmission line projects is over five years from the commissioning of solar and wind projects [[1]]. Due to the unavailability of adequate transmission infrastructure, it becomes a big challenge for the investors to evacuate the power from their solar and wind plants to the grid, and this in turn puts pressure on the project developers [[2]]. A study case is the state of Rajasthan, where the state energy dept. had stopped giving approvals for power evacuation, without which solar parks of nearly 3700 MW capacity are waiting for nearly 3 months to get the approval to inject the energy into the grid [[3]]. Similarly, the state of Tamil Nadu, whose coastline has proved very conducive for setting up wind energy plants in the past few years, is facing a slowdown in the development of the sector [[4]]. This slowdown can largely be attributed to the power evacuation problems faced in the state. Thus, the additional transmission infrastructure needs to be revamped to bring the electricity from solar and wind project sites to the demand centres. This is being set up by the Govt. of India through its Green Energy corridor program which targets to develop more than 9400 circuit kilometres of installed transmission lines [[5]]. This ongoing Green Energy corridor program is vital, as it will facilitate grid integration and power evacuation of these renewable energy sources & will also aid India in progress towards achieving its target of 500 GW installed RE capacity by 2030 [[6]]. Developed countries like the USA, Germany, etc., have RE capacity expansion plans linked with the transmission expansion plans. [[7]]. It is the transmission expansion planning which guides the investment for setting up renewable energy power plants rather than the conventional approach wherein we add the RE capacity and then look for addressing the issues curtailment. NREL has proposed the idea of creation of Renewable Energy Zones (REZ), which ensures easy ramping up of transmission infrastructure & transmission line extension in the future from the location of the plants [[8]]. This method could prove beneficial to overcome the technical challenge of upgrading the transmission infrastructure & power evacuation in India. Changes in the transmission infrastructure like adding transmission flexibility through a combination of HVDC & AC controllability of power flow and the adoption of smart grid systems can limit the transmission bottleneck.

The lack of transmission infrastructure and poor forecasting and scheduling capability, in the Indian context, leads to the curtailment of RE sources on account of technical grid safety. Though the RE sources are considered as MUST RUN sources as per the Electricity Rules, 2021 [[9]], issued by the Ministry of Power. As per these rules, curtailment of must-run renewable power plants is only to be allowed for the security of the grid. However, there have been reports of energy curtailment in states such as Andhra Pradesh, Telangana, Karnataka, Tamil Nadu, Madhya Pradesh & Rajasthan [[10]]. There is a lack of transparency in the reason offered by the respective State Govts. for these curtailments. But analysis based on the IEA India Regional Power System Model [[11]], suggests that the factors leading to curtailment include lack of transmission infrastructure for interstate trade, inflexible contract structures such as long-term PPA (power purchase agreement) between DISCOMs & generators, etc. These factors contribute to a curtailment of nearly up to 3% of the renewable power plant’s annual output as observed in states like Tamil Nadu, Karnataka, etc. in recent years [[12]]. The curtailment issues were observed on large-scale power systems in recent years, across eleven countries in Europe, North America, and Asia, respectively [[13]]. In most of these countries, the curtailment levels have mostly been similar to India, around 1-3% of the generated capacity [[14]].

A variety of factors, such as the generation mix, market structure, operating rules, and transmission grid, affect the operation of renewable energy generators, and hence the potential for curtailment.[15] The countries such as China, and the USA, where the RE penetration is very high, the curtailment in some of the years have been as high as over 10% [[16]]. Lack of adequate investments in transmission systems leads to curtailment in most cases. The possible solutions that have been proposed to reduce energy curtailment are the increased investment in transmission capacity, operational changes, revamping of transmission infrastructure & subsequent upgrades to smart-grid technology [[17]].  Niti Aayog’s report highlights that the curtailment needs to be addressed by adding more grid flexibility through the introduction of energy storage systems, better demand forecasting, and RE scheduling, introducing the time of use tariff, creating inter-regional power transmission infrastructure, adding the agriculture pumping as part of demand response programs. Changes addressing the risk of the offtaker with regard to curtailment should be added to the PPA. Compensating the power developer for the costs of generation in case of curtailment can also be seen as a solution to mitigate curtailment. Many countries have also adopted methods like insurance products and guarantees along with Forecasting & scheduling and deviation settlement. [[18]] Therefore, the implementation of these practices in India could be vital to achieving a reduction in generation curtailment levels.

^[1] Prateek S. Lack of Transmission Capacity a Growing Concern for Solar and Wind Companies [Internet]. Mercom India. 2018 [cited 2022 Mar 21]. Available from: https://mercomindia.com/transmission-capacity-concern-solar-wind/.

[2] NITI Aayog, IEA. Microsoft [Internet]. Renewables Integration in India 2021. 2021 [cited 2022Aug16]. Available from: https://iea.blob.core.windows.net/assets/7b6bf9e6-4d69-466c-8069-bdd26b3e9ed1/RenewablesIntegrationinIndia2021.pdf

^[3] TNN. Delay in power evacuation nod stalls solar park development [Internet]. The Times of India. 2021 [cited 2022 Mar 21]. Available from: https://timesofindia.indiatimes.com/city/jaipur/delay-in-power-evacuation-nod-stalls-solar-park-devpt/articleshow/86380055.cms.

^[4] Renewable Watch. Frontrunner States [Internet]. renewablewatch.in. 2020 [cited 2022 Mar 21]. Available from: https://renewablewatch.in/2020/11/08/frontrunner-states/.

^[5] Renewable Watch. Transmission Troubles [Internet]. renewablewatch.in. 2020 [cited 2022 Mar 21]. Available from: https://renewablewatch.in/2020/12/03/transmission-troubles/.

^[6] Drishti IAS. Green Energy Corridor [Internet]. drishtiias.com. 2022 [cited 2022 Mar 21]. Available from: https://www.drishtiias.com/daily-updates/daily-news-analysis/green-energy-corridor.

^[7] Bloom A. Transmission Planning for 100% Clean Electricity [Internet]. Energy Systems Integration Group (ESIG). 2021 [cited 2022 Mar 21]. Available from: https://www.esig.energy/wp-content/uploads/2021/02/Transmission-Planning-White-Paper.pdf.

^[8] Lee N, Flores-Espino F, Hurlbut D. Renewable energy zone (REZ) transmission planning process: A … – NREL [Internet]. NREL. 2017 [cited 2022Aug16]. Available from: https://www.nrel.gov/docs/fy17osti/69043.pdf.

^[9] Ministry of Power (MoP). Electricity (Promotion of Generation of Electricity from Must-Run Power Plant) Rules, 2021 [Internet]. powermin.gov.in. New Delhi: Ministry of Power, Government of India; 2021 [cited 2022 Mar 21]. Available from: https://powermin.gov.in/sites/default/files/Electricity%20%28Promotion%20of%20generation%20of%20Electricity%20from%20Must-Run%20Power%20Plant%29%20Rules%2C%202021.pdf.

^[10] Sarthak Advocates & Solicitors. Benefits of must-run status for renewable energy generators [Internet]. law.asia. 2021 [cited 2022 Mar 21]. Available from: https://law.asia/benefits-of-must-run-status-for-renewable-energy-generators/.

^[11] Das B. Renewable energy integration in India: Ways to maximise solar, wind power system [Internet]. DownToEarth. 2021 [cited 2022 Mar 21]. Available from: https://www.downtoearth.org.in/blog/energy/renewable-energy-integration-in-india-ways-to-maximise-solar-wind-power-system-78391.

[12] NITI Aayog, IEA. Microsoft [Internet]. Renewables Integration in India 2021. 2021 [cited 2022Aug16]. Available from: https://iea.blob.core.windows.net/assets/7b6bf9e6-4d69-466c-8069-bdd26b3e9ed1/RenewablesIntegrationinIndia2021.pdf.

^[13] Bird L, Lew D, Milligan M, Carlini EM, Estanqueiro A, Flynn D, Gomez-Lazaro E, Holttinen H, Menemenlis N, Orths A, Eriksen PB. Wind and solar energy curtailment: A review of international experience. Renewable and Sustainable Energy Reviews. 2016 Nov 1;65:577-86. https://doi.org/10.1016/j.rser.2016.06.082.

[14] Ministry of Power (MoP). Electricity (Promotion of Generation of Electricity from Must-Run Power Plant) Rules, 2021 [Internet]. powermin.gov.in. New Delhi: Ministry of Power, Government of India; 2021 [cited 2022 Mar 21]. Available from: https://powermin.gov.in/sites/default/files/Electricity%20%28Promotion%20of%20generation%20of%20Electricity%20from%20Must-Run%20Power%20Plant%29%20Rules%2C%202021.pdf.

[15] Bird L, Cochran J, Wang X. Wind and solar energy curtailment: Experience and practices in … – NREL [Internet]. NREL. 2014 [cited 2022Aug17]. Available from: https://www.nrel.gov/docs/fy14osti/60983.pdf.

^[16] Wind and solar energy curtailment: A review of international experience

^[17] Indian Renewable Energy Federation (IREF). Addressing Barriers To ScalingUp Renewable Energy Through Industry Involvement [Internet]. shaktifoundation.in. Shakti Sustainable Energy Foundation; 2019 [cited 2022 Mar 21]. Available from: https://shaktifoundation.in/wp-content/uploads/2014/02/Main-Report.pdf.

[18] NITI Aayog. Report on India’s Renewable Electricity Roadmap 2030: Towards Accelerated Renewable Electricity Deployment [Internet]. NITI Aayog. 2015 [cited 2022Aug17]. Available from: https://shaktifoundation.in/wp-content/uploads/2017/08/Report-on-Indias-RE-Roadmap-2030-full-report-web2.pdf. 

Transmission capacity related barriers to large-scale deployment of renewable energy in India can be summarised in the following table: