Modelling 24/7 Carbon Free Electricity in India

Detailed grid modelling shows round-the-clock renewables can support India's energy and manufacturing ambitions

System Modelling

24/7 CFE

Summary

Indian Prime Minister Modi made a pledge at COP26 in 2021 to reach 500 GW of non-fossil capacity by 2030, while the Union Budget 2025 emphasised the strengthening of domestic manufacturing. Achieving these goals simultaneously requires low-cost, 24/7 carbon free energy (CFE) — sometimes referred to as round-the-clock (RTC) clean energy.

We built a detailed, open-source model of India’s electricity grid to explore the costs and benefits of 24/7 CFE for grid planners and corporate buyers. Specifically: if just 5% of India’s electricity demand were matched with 24/7 CFE by 2030, what would be the cost, investment, and emissions implications?

The results show India can add 70% of 24/7 CFE equalling 52 GW by 2030 at lower cost compared to annual matching — saving grid operators US$1 billion (almost Rs. 9 thousand crore) per year. In addition, the carbon abatement costs are roughly three times cheaper compared to annual matching.

India’s twin ambitions

The COP26 announcement by Prime Minister Modi, setting a goal of 500 GW of non-fossil fuel capacity by 2030, marked a watershed moment in India’s energy transition. The Union Budget 2025, the third in India’s 25-year roadmap to its 100th year of independence, emphasised the importance of strengthening domestic manufacturing. As a continent-sized country with the world’s largest population and relatively low per capita income, India faces both opportunities and challenges as it transforms its electricity supply while expanding its manufacturing base.

At the heart of India’s energy and manufacturing ambitions is the ability to generate round-the-clock (RTC) clean electricity, known as 24/7 carbon free energy (CFE), at the cost and scale required to sustain the country’s rapid economic development. In this report, we use the term 24/7 CFE to refer to electricity that is matched hour-by-hour with carbon free generation. As energy planners and grid operators work to integrate growing shares of variable renewable energy (VRE), and as companies and developers prepare for upcoming changes to Greenhouse Gas Protocol (GHGP) accounting, the key question is: what exactly is 24/7 CFE?

What is 24/7 Carbon Free Energy (CFE)?

Wind and solar, the cheapest sources of clean energy today, are variable by nature. Electricity consumers seeking to decarbonise their electricity use with VRE face a persistent mismatch between when clean power is generated and when it is needed. The dominant approach to procuring and accounting for emissions reductions is based on ‘annual matching’. This involves corporations matching their consumption of electricity with the supply of clean electricity over a year – which results in cycles of surplus and deficit, and fossil-based generators must be relied upon to pick up the slack, introducing emissions. By matching every hour of electricity use with electricity from carbon free sources rather than matching it on an annual basis, we can move closer to a decarbonised grid.

This approach is a central focus of the GHGP, which governs how companies account for emissions from purchased electricity, and is in the process of a multi-year revision of its standards. While hourly emissions accounting is emerging as the preferred accounting method, the GHGP does not set targets or grade performance.

How well a consumer is meeting their 24/7 CFE goal can be summarised by their CFE score for any given hour. This is calculated by looking at what percentage of their generation comes from carbon free sources, and considers both the generation from CFE power purchase agreements (PPAs), as well as the CFE score of imported electricity from the grid. In the case of India, this considers each of the five grid zones as having distinct hourly CFE scores. To calculate the scores, we follow the methodology set out by Google.

What are the cost, investment and emission implications of a 24/7 CFE for India?

Hourly-matched accounting and procurement effectively values resources that provide dispatchability and flexibility, raising a critical question: what are the cost, investment, and emissions implications of transitioning from annual to hourly matching? This is especially important for a low- to middle-income country like India.

We built a detailed, open-source model of India’s electricity grid to explore the implications of 24/7 CFE for corporate buyers and grid planners. Specifically:

What does switching from annual to hourly matched procurement mean for corporate buyers from a cost and supply perspective?
What are the costs and benefits of this change in procurement strategy for the grid i.e. does it increase or decrease costs, investments and emissions?

Model setup: optimising India’s 2030 grid

To answer these questions, we developed an open source grid dispatch or production cost model in the Python for Power System Analysis (PyPSA) modelling package. This model represents an NDC-compliant Indian grid in 2030 with 5-node spatial resolution, and 8760-hour temporal resolution. With this model, we were able to test different levels of 24/7 CFE with different generation technology configurations, or palettes, to understand the cost, investment and emissions implications. Our methodology replicates the approach used by Brown and Riepin (2022). For more information on the methodology, please refer to our modelling methodology documentation.

The reference grid used in this study assumes India meets its 2030 climate commitments (NDCs), as well as reaching 500 GW of non-fossil fuel capacity. To meet these goals cost-effectively, the model doubles onshore wind capacity and quadruples solar. Battery storage builds up to 44 GW, based on recent state-level targets. Generating technologies are also built whilst adhering to supply chain and pipeline constraints. This projected grid, while not the study’s main focus, plays an important role in how hourly clean electricity strategies (like 24/7 CFE) perform. A cleaner grid supports C&I consumers by making it easier to meet 24/7 CFE targets, while a dirtier grid would require larger clean portfolios and shift more clean energy from private portfolios back to the grid.

In each grid zone we assign 5% of the total grid zone demand to commercial and industrial consumers participating in clean electricity matching.
We model this 5% as following either annual matching or hourly matching (with the target of between 70%-100% 24/7 CFE). These scenarios inevitably require additional clean power generating assets, which were built and optimised within the model.

We combine the grid-zone level results to see the big picture across the whole Indian power sector, including generation, storage, transmission and distribution.

What we found

High levels of 24/7 CFE can deliver corporate buyer and grid planner savings

70% 24/7 CFE clean electricity by 2030 is 35% cheaper than 100% annual matching, delivering net system savings of US$1 billion per year. It also provides additional benefits, including lower emissions and reduced curtailment of renewables.

Operational savings for the grid continue to grow as CFE targets rise — driven by increased clean energy exports, reduced reliance on expensive thermal generators, and the falling cost of batteries to store surplus renewable electricity.

However, 70% 24/7 CFE is the clear sweet spot: it delivers major cost savings, emissions reductions, and improved system efficiency. While pushing beyond 70% slightly reduces net system savings due to higher infrastructure requirements, it still results in significant benefits, with US$270 million in savings at the 80% 24/7 CFE level.

80%+ 24/7 CFE comes with a cost premium

While 70% 24/7 CFE can be delivered at a lower cost than annual matching at the system level, participating C&I consumers may face higher capital and operational costs — particularly when aiming for 80% CFE and above. This is due to the need for larger clean energy portfolios, significant oversizing, and storage to cover harder-to-decarbonise hours. There may be additional expenses like transmission and wheeling charges, open access fees, and other grid surcharges, which are not included in the core cost estimates. These consumer costs are also subject to regulatory uncertainty, with tariffs and policies varying by state and frequently changing.

VRE and batteries can get you to 100% CFE

100% 24/7 CFE is achievable, using a combination of VRE and battery storage, with solar and 4-hour batteries forming the most cost-effective and reliable configuration. Pairing each MW of generation with around 2 MWh of battery storage ensures CFE power across most hours, with solar-charged batteries often costing less than onshore wind.

However, moving from 80% to 100% 24/7 24/7 CFE requires a substantial increase in capacity and costs to cover those final ‘hard-to-reach’ hours. At 100% CFE, the oversizing ratio required for CFE PPA-procured capacity reaches ten times the peak load.

Due to India’s large geographic size and excellent wind and solar resources, our modelling shows that short-duration batteries are sufficient for 100% 24/7 CFE, with long-duration energy storage (LDES) playing only a minimal role.

24/7 CFE results in greater emission reductions at a lower abatement cost

Model results show that even with just the 5% of national demand meeting 24/7 CFE, emissions across the whole system drop by 7%. And the emissions savings remain greater compared to annual matching scenarios no matter what the 24/7 CFE target. It’s also cheaper to achieve those savings: the average abatement cost under 70% 24/7 CFE is roughly one third the abatement cost under annual matching.