As the world’s cities continue to grow vertically and horizontally, the demand for uninterrupted, high-voltage power supply is becoming increasingly non-negotiable. With rising urban density and space constraints, traditional power infrastructure solutions are proving inadequate. This is where Gas Insulated Substations (GIS) have emerged as a game-changing innovation, redefining the landscape of electrical infrastructure in urban settings, notes Raghavendra Mirji.
Traditionally, Air Insulated Substations (AIS) have been the backbone of power distribution. However, their significant spatial requirements make them impractical in modern cities where land is both scarce and expensive. While GIS a compact, robust, and high-performance solution that replaces open-air insulation with SF₆ (sulphur hexafluoride) gas, enabling the entire substation to occupy a fraction of the land footprint required by AIS.
The evolution of GIS is about space efficiency and better safety, reduced maintenance, and higher reliability. Enclosed within metallic chambers, GIS equipment is protected from environmental factors such as pollution, humidity, and extreme temperatures thus making it ideal for both indoor and underground installations in megacities.
Why GIS is Gaining Ground in Urban Centres
India’s urbanisation is on a steep upward trajectory. With half of the population projected to live in cities by 2047, sustainable urban environments need to be created using modern tools and wisdom. To support this, cities require not only more power but also smarter, space-optimised ways to distribute it. GIS substations are becoming a preferred solution for utilities and infrastructure developers due to several advantages:
- Space optimisation: GIS requires up to 90% less space than AIS, making it highly suitable for densely populated areas.
- Enhanced safety: The enclosed design limits the risk of accidental contact and arc flash incidents.
- Minimal maintenance: GIS installations are sealed, resulting in reduced exposure to weather and pollution-related wear.
- Longer service life: With better reliability and lower degradation, GIS installations often outlive their AIS counterparts.
This compactness and durability have made GIS integral to projects ranging from metros and commercial complexes to high-rise residential buildings and data centres.
Navigating the Challenges: Cost, Complexity and Competence
While the benefits are clear, deploying GIS technology comes with its own set of challenges. The initial capital cost is typically higher than AIS due to advanced equipment, specialised civil construction, and the expertise required for installation and commissioning.
The testing and commissioning of GIS equipment is intricate, demanding advanced competencies, especially for critical activities like EHV cable terminations. Maintenance, though less frequent, is technically intensive and time-consuming, often requiring highly trained personnel and specialised tools. Moreover, the entire GIS system must be leak-proof to prevent SF₆ gas emissions—no small feat considering the environmental implications.
The civil component in GIS construction also demands a higher standard: PU-coated dust-free flooring, air-conditioned or controlled environments, and multi-level structures with precise tolerances are mandatory to ensure operational efficiency and equipment longevity.
Despite these complexities, the long-term operational and spatial advantages make GIS an increasingly compelling choice for India’s growing cities.
Engineering for Density: The Case of Mumbai’s First Vertical 400/220 kV GIS Substation
At the Energy Solutions business of Godrej Enterprises Group, we approach GIS substation projects as engineering tasks, especially Mumbai’s first 400KV GIS Substation at Vikhroli. The key lies in customising every aspect of the substation, from layout and control systems to cooling mechanisms, to meet the constraints and requirements of the site.
Commissioned to meet the megacity’s growing electricity demand, this vertical GIS substation represents a paradigm shift in design and engineering. Installed within a compact footprint of just 8,800 sqm, 92 per cent smaller than a conventional AIS setup, saving almost 30 per cent land area, it delivers 1,500 MVA capacity at without the need for sprawling switchyards or large land acquisitions.
Executing such a complex substation involved solving layered challenges: limited space, tight timelines, high-floor civil work, conductor stringing at height, and critical cable housing. Our engineering and execution teams rose to the occasion, adopting a structured design-release process, synchronising with subcontractors and suppliers, and maintaining disciplined on-site coordination.
Conclusion: Powering Tomorrow’s Cities Today
As cities become smarter and more sustainable, the electrical infrastructure powering them must evolve in tandem. Gas Insulated Substations represent a future-ready solution that addresses the twin challenges of space and reliability in the urban energy ecosystem. With innovations in design, material science, and sustainability, GIS will continue to play a pivotal role in shaping the resilient power systems of tomorrow. The question is not whether cities will adopt GIS technology, but how quickly they can implement these solutions to meet the growing demands of urban India.
Raghavendra Mirji is EVP & Business Head, Energy Solutions Business of Godrej Enterprises Group