Energy storage and renewables synergy: A need to go forward

In India, the increasing addition of renewable energy sources to the power mix, and the imminent advent of electric mobility has driven the market to look at grid-scale energy storage solutions.

Grid-scale energy storage would support the sustainable growth of renewable integration and aid grid balancing efforts increasing energy security and reliability.

Most global efforts towards climate change adaptation have happened in the form of renewable energy additions to the power sector. Development of the storage sector was imminent, and unsurprisingly, the global market in 2018 was estimated at 12 Gigawatt Hour (GWh).

The International Renewable Energy Agency predicts the global energy storage capacity to triple by 2030.

The United States has led from the front, with serious discussions around mandated storage; California has set itself a target of 1.3 Gigawatt (GW) of storage by 2020, while New York will install another 3 GW by 2030.

Development of the energy storage sector is vital if India is to meet its 2022 target of 175 GW. The first tender was released in 2015, and since then, the frequency of tenders with battery energy storage systems (BESS) have steadily increased, highlighting India’s motivations.

Several tenders for solar plants with storage were released by the Solar Energy Corporation of India (SECI), Neyveli Lignite Corporation, and Rajasthan Electronics & Instruments Limited (REIL), some of which are given below:

1. In March 2018, NLC issued 20 MW (8 MWh) solar PV with BESS power plant tender in the Andaman & Nicobar Islands.

2. In August 2018, SECI issued a 160 MW Solar-Wind Hybrid plant with BESS in Andhra Pradesh and 2 MW (1MWh) Solar PV with BESS in Himachal Pradesh.

3. In February 2019, SECI issued a tender for a 1.2 GW inter-state transmission system across India, which was oversubscribed by 0.9 GW.

4. In March 2019, SECI issued a 14 MW (42 MWh) solar PV plant in Leh & Kargil. In April 2019, REIL issued a tender for a 1.7 MW (1 MWh) solar PV plant in Andaman & Nicobar.

5. In May 2019, SECI issued a 20 MW (60 MWh) floating Solar PV plant with BESS in Lakshadweep.

The introduction of the National Energy Storage Mission announced in 2018 was a commendable effort too. However, the current storage market seems restricted to battery energy storage systems.

For a grid-scale storage, cost incurred per unit energy stored is heavily dependent on ramping time, efficiency and life of storage. Technologies like Pumped Hydro (PHES), Compresses Air (CAES) and Gravity storage (GS) are sound alternatives to battery storage.

Hence, to involve the entire basket of possibilities, the Union Ministry of New and Renewable Energy (MNRE) in August 2018, amended the Solar-Wind Hybrid Policy to include storage and not just BESS.

Of these, PHES and CAES are tested and proven technologies globally. According to the International Electrochemical Commission, global installation of PHES is at 135 GW and that of CAES at 440 MW.

PHES facilities are operational in places like Srisailam in Andhra Pradesh, Purlia in West Bengal and others, net amounting to 4,785.60 MW as on January 2019, according to the Central Electricity Authority.

Gravity Storage (GS), a relatively newer find, is steadily gaining traction too. A pilot installation of 4 MW (35 MWh) is already in process by Tata Power, with support from Energy Vault. Following which, the MNRE released an invitation for proposals for GS projects.

GS works on the principle of elevating up a solid mass to a height while charging or storing energy and elevating down the same mass while discharging or using the stored energy.

GS is independent of the geographic location it is installed in unlike PHES, wherein water is used as mass, hence making it location-specific.

The Indian government’s vision of greening the power sector will require large scale adoption of storage technologies. Unfortunately, it is being met by a host of hurdles — relatively high cost of technology and a lack of sector experience.

India will have to capitalise on the developments in the global market, where increasing competition is reducing costs and improving quality.

Maulik Ruparel is a Research Intern at the Centre for Science and Environment, New Delhi