As renewable energy deployment accelerates globally, energy storage systems and grid flexibility solutions are becoming critical for maintaining reliable power systems. The article explores the role of battery storage, demand response, and transmission technologies in supporting large-scale renewable integration and climate goals.
Climate change has prompted the world to reduce emissions of greenhouse gases — principally carbon dioxide, but also methane, which is approximately 20 times more potent as a warming agent. Extreme weather events, rising global temperatures, increased ocean temperatures, and climbing sea levels are among the consequences of these emissions, all of which are adversely affecting ecosystems worldwide. If left unchecked, crops will suffer, coastal cities will face inundation, and both marine and terrestrial life will be severely impacted.
The percentage breakdown of global man-made greenhouse gas emissions for 2023 is shown in the figures below, alongside the historical rise in carbon dioxide emissions.
To mitigate these impacts, global policy has pivoted sharply towards reducing carbon emissions across all industries. The carbon dioxide emissions emitted by each category is given below.
The power sector accounts for the largest share — 29 per cent of total emissions — driven primarily by coal-based thermal power plants. Reducing carbon output from electricity generation would therefore have the single greatest impact on arresting climate change.
The current international target is to limit the rise in global temperatures to 1.5 degrees Celsius above pre-industrial levels (the average for 1850–1900) by the end of this century. We have already crossed 1.1–1.3 degrees Celsius. The margin for error is narrow, and the case for urgent action is clear.
The power sector's dominant share of global emissions has driven a concerted policy shift towards renewable energy — principally solar and wind. In India, the Government launched the National Solar Mission in 2010 with a target of 20 GW of grid-connected solar power by 2022. This was revised sharply upward in 2014 to 100 GW. Wind power targets were set at 60 GW, with all renewable sources combined targeting 175 GW by 2022.
Solar and wind energy are inherently intermittent — dependent on nature and therefore variable in output. It follows logically that when generation from these sources falls, energy storage systems must be ready to compensate: absorbing surplus energy when renewables overproduce, and returning it to the grid when supply falls short.
Historically, pumped hydro storage was the only technology capable of storing energy at meaningful scale. However, these plants typically take eight to ten years to build. From around 2010–12, global exploration into electrochemical — or battery — storage at grid scale began in earnest. The technology has since matured considerably, with lithium-ion leading the way. Costs have fallen by approximately 90 per cent since 2010. Today, global battery storage capacity stands at around 270 GW, with an energy quantum of approximately 630 GWh.
Lithium-ion batteries are well suited to short-duration storage — up to four hours of full discharge — but become prohibitively expensive for longer durations. This has spurred growing deployment of flow batteries, which can provide storage of 12 hours or more. Among those already commercialised are sodium-ion flow batteries and vanadium redox batteries. Others, including metal-air batteries, are on the path to commercialisation and are projected to be significantly cheaper than lithium-ion for long-duration applications.
The solutions described above are supply-side in nature. Yet significant potential exists on the demand side, and this remains underutilised — even in Europe, despite an EU directive to member states to facilitate demand response as far back as 2012–14. As of 2024–25, demand-side response (DSR) accounts for approximately 10 per cent of total grid flexibility in Europe, with projections suggesting this will rise to around 21 per cent by 2030.
Demand response refers to the voluntary reduction of electricity consumption by a consumer in exchange for a financial incentive. In grid terms, a consumer choosing to reduce demand has the same effect as bringing additional standby generation online — both restore the balance between supply and demand.
In India, demand response was introduced as a concept in the Tariff Policy in January 2016. Regulations under the Central Electricity Regulatory Commission (CERC) for market-based Ancillary Services — which included demand response for the first time in India — came into effect for the inter-state area in 2022. Detailed procedures for Tertiary Reserve Ancillary Services (TRAS) were finalised in April 2023, with market-based TRAS becoming effective from 1 May 2023.
However, the majority of consumers reside in states, and Ancillary Services regulations have been adopted by only four states: Maharashtra, Karnataka, Assam, and Madhya Pradesh. Even in these states, demand response has yet to take off meaningfully. Maharashtra conducted a pilot using an aggregator-based model around 2011, following approval by the Maharashtra Electricity Regulatory Commission (MERC) for the Tata Distribution company in Mumbai. Little has progressed since.
Automated Demand Response holds particular promise in states where smart meters have been deployed. The Indian consumer is highly price-sensitive, and if given the opportunity to reduce electricity bills by responding to grid signals, uptake could be substantial.
A practical example: a household consumer can reduce costs by running a storage water heater during periods of surplus power — at night or during peak solar hours. During solar hours, power exchange prices — an indicator of the national demand-supply balance — can fall below Rs. 2 per unit. They have, on occasion, dropped to near zero: the lowest recorded to date was zero paise per unit on 1 May 2026, and 0.005 paise per unit on 3 May 2026, in the real-time market.Household appliances can also be programmed to activate when prices are low and switch off when prices rise. Similarly, given India’s rapid expansion into electric vehicles (EVs), EV chargers can participate in demand response — increasing charging rates when grid power is abundant (and prices are low) and reducing them when supply is tighter (reflected in higher prices).
A two-tariff framework could be introduced by State Electricity Regulatory Commissions (SERCs): a reliable supply tariff (offering 99 per cent supply reliability) and an interruptible tariff (offering, say, 70 per cent reliability). The Distribution System Operator could then curtail supply to interruptible customers — via remote disconnection of smart meters — when instructed by the System Operator. Consumers could divide their loads between essential and non-essential uses accordingly, paying differentiated tariffs for each.
If more states adopt Ancillary Services Regulations with demand response provisions, the required deployment of physical storage could be substantially reduced. Demand response is, in fact, the most cost-effective tool available for managing the intermittency of renewable energy.
Beyond generation balancing, flexibility is also required in the transmission and distribution system to ensure optimal utilisation and safe, secure grid operation.
Several technical solutions can decongest the transmission network by redistributing power flows from congested corridors to uncongested ones. These include Thyristor Controlled Series Compensation (TCSC) and phase-shifting transformers, which modify fundamental transmission parameters such as reactance and relative phase angles. Reactive power compensators — Static VAR Compensators (SVCs) and Static Synchronous Compensators (STATCOMs) — help manage the reactive power fluctuations that arise from the variability of intermittent renewable sources.
The current-carrying capacity of transmission lines can also be enhanced through Dynamic Line Rating (DLR), which allows higher loading when ambient temperatures are lower or wind speeds are elevated. In practice, this means lines can carry more current at night than during the day, and more in winter than in summer. Temperature and wind speed data along a line can be gathered using sensors placed at intervals on transmission towers; a more innovative approach involves drones that measure these parameters along the line while recharging themselves via induction from platforms mounted on the towers.
Additionally, a new transmission line can safely handle an overload of up to 40 per cent for 30 minutes in the event a parallel line trips — without thermal damage. This too can serve as a congestion management tool.
Integrating renewable energy into the grid efficiently is achievable. The technical means — from battery storage and demand response to advanced transmission technologies — are available. What is required now is the will and the frameworks to put them in place.
About the Author
Pankaj Batra has over 42 years of experience across multiple aspects of India’s power sector, including policy, regulation, planning, renewable energy integration, power markets, and electric vehicles. He is currently Senior Advisor at IRADe, a leading think tank in India and South Asia, and works as an independent consultant. He previously served as Chairperson and Member (Planning) of the Central Electricity Authority, Government of India, and as Chief (Engineering) at the Central Electricity Regulatory Commission. He has also led regional energy integration initiatives in South Asia under USAID’s SARI/EI programme and has worked as an Asian Development Bank consultant.