Q2Non-Conventional Energy Sources

(a) Indian Energy Scene

India's energy scene is characterized by rapidly growing total energy demand driven by economic growth, industrialization, and rising per-capita consumption, combined with historically heavy reliance on coal for electricity generation (owing to India's large domestic coal reserves) and significant dependence on imported crude oil and natural gas to meet transportation and industrial fuel needs, creating both energy security concerns and a substantial energy import bill.

In recent years, India has pursued an aggressive renewable energy expansion program, with installed solar and wind capacity growing dramatically as part of national and international climate commitments (including targets under the Paris Agreement and India's own National Action Plan on Climate Change), supported by policy mechanisms such as feed-in tariffs, renewable purchase obligations for utilities, solar park development, and international initiatives such as the International Solar Alliance headquartered in India. The country's energy mix remains transitional - coal continues to supply the majority of electricity generation for grid stability and base-load reliability, while renewable capacity (solar, wind, and to a lesser extent biomass and small hydro) is being added at a very rapid rate to diversify the generation mix, reduce emissions intensity, and improve energy security by reducing fossil fuel imports.

Rural electrification and universal household electricity access have also been major national priorities, achieved substantially through grid extension combined with decentralized renewable solutions (solar home systems, micro-hydro, and biomass-based mini-grids) in remote areas where extending the central grid is not economically viable, reflecting the broader Indian energy policy theme of using non-conventional energy sources not merely as a supplementary contribution to the existing grid but as a primary electrification tool in underserved regions.

(b) Components of Tidal Power Plants and Double Basin Arrangement

The main components of a tidal power plant include: the barrage (dam) constructed across the mouth of the tidal estuary/bay, which impounds the basin and separates it from the open sea; sluice gates, which allow controlled filling and emptying of the basin at appropriate points in the tidal cycle; turbines (typically bulb-type or Kaplan-type axial-flow turbines specifically designed for the low-head, bidirectional flow characteristic of tidal application), which convert the flowing water's kinetic and potential energy into rotational mechanical energy; generators, coupled to the turbines, which convert this mechanical energy into electrical energy; and the powerhouse structure housing the turbine-generator units, along with the transmission and grid-interconnection infrastructure carrying the generated power to the load centers.

The double basin arrangement uses two separate basins (an upper/high basin and a lower/low basin) instead of a single basin, connected to each other and to the sea through separate sets of sluices and turbines: the high basin is filled from the sea during high tide and retains water at a relatively high level, while the low basin is emptied to the sea during low tide and retains water at a relatively low level, so that a head difference is maintained between the two basins at essentially all times (unlike a single-basin scheme, where the head available for generation falls to zero twice per tidal cycle as the basin level equalizes with the sea) - power is generated continuously by allowing water to flow from the high basin through turbines into the low basin whenever needed, independent of the instantaneous state of the tide in the open sea, giving the double-basin scheme the significant advantage of being able to supply power on demand (dispatchable generation) rather than being rigidly tied to the fixed timing of the tidal cycle, at the cost of the additional civil-engineering complexity and capital cost of constructing and maintaining two separate basins rather than one.

A useful example illustrating the practical operation of tidal barrages is the La Rance tidal power station in France, one of the earliest and longest-operating large-scale tidal barrage plants, which has demonstrated over several decades that a well-engineered barrage scheme can provide a stable and predictable, if intermittent, contribution to the grid with very low ongoing operating cost once the substantial initial capital investment is recovered. Such long-running installations also provide valuable long-term data on sediment accumulation, ecological adaptation within the impounded basin, and turbine maintenance requirements, informing the design of subsequent tidal projects worldwide.

Beyond the double-basin arrangement, other engineering approaches to improving tidal power dispatchability include tidal lagoons (artificial impoundments built along a coastline rather than across a natural estuary, offering more site flexibility since they do not require a naturally funnel-shaped bay) and tidal stream (in-stream) turbines, which resemble underwater wind turbines and extract kinetic energy directly from fast-flowing tidal currents without requiring any barrage or basin construction at all - these avoid many of the large-scale ecological and sedimentation concerns associated with barrage schemes, since they do not impound or redirect the natural tidal flow, though they typically have lower per-unit power output and are still a comparatively less mature technology than barrage-based generation.

From an Indian context, potential tidal power sites have been identified in the Gulf of Kutch and the Gulf of Khambhat in Gujarat, and in the Sundarbans delta region of West Bengal, owing to their comparatively large tidal ranges relative to other Indian coastal areas, though none of these sites has yet been developed into a large-scale commercial tidal barrage plant, reflecting the broader global pattern in which tidal power remains a niche, site-specific renewable technology rather than a widely deployed one, primarily due to the high capital cost and the very limited number of geographically suitable locations.

The Indian energy scene also reflects significant regional variation in resource availability and grid infrastructure maturity, with states such as Rajasthan, Gujarat, and Tamil Nadu emerging as leading renewable energy hubs due to their favorable solar irradiance and wind resource characteristics respectively, while other regions with more limited direct renewable resource but strong industrial demand rely more heavily on inter-state power transmission (and associated planning for adequate transmission corridor capacity) to access renewable generation from resource-rich states, illustrating that India's renewable energy transition is as much a transmission and grid-planning challenge as it is a generation-technology deployment challenge.

The double-basin tidal scheme's key dispatchability advantage over a single-basin scheme is particularly relevant to Indian tidal power development context, since India's identified tidal potential sites (the Gulf of Kutch and Gulf of Khambhat in Gujarat, and the Sundarbans in West Bengal) each present their own site-specific combination of tidal range, estuary geometry, and environmental sensitivity considerations that would need to be weighed against the additional capital cost of a double-basin configuration versus the simpler, lower-cost single-basin alternative during the detailed feasibility and design phase of any actual Indian tidal power project development.