Alternatives to Rogun HPP, including different dam heights and other renewable technologies, were thoroughly assessed during the Techno-Economic Assessment Studies (TEAS) for the Rogun Hydropower Project (HPP) financed by the World Bank between 2011 and 2014, and during the financing options study in 2021. The highest dam alternative was selected based on its superior economic and environmental performance. Updated analysis performed during project appraisal confirmed that Rogun HPP remains the least-cost solution for providing clean and affordable electricity, supporting the region's transition to a low-carbon future.
1. Alternative Dam Heights
The TEAS studies evaluated various dam height alternatives to determine the most suitable option for the project. Three full supply levels (FSL) were considered, corresponding to dam heights of 335 meters (corresponding to full supply level (fsl) of 1290 meters above sea level (masl), 300 meters (corresponding to fsl of 1255 masl), and 265 meters (corresponding to fsl of 1220 masl). Each height was analyzed for different installed generation capacities, ranging from 3,600 MW to 2,000 MW, resulting in a total of nine alternatives studied.
The TEAS concluded that all three dam height alternatives could be built and operated within international safety norms, provided that specified design modifications and mitigation measures were implemented. The highest dam alternative, at 1,290 masl, was found to offer the greatest benefits across most economic and environmental sensitivities. The TEAS recommended the highest option due to its superior performance in terms of energy generation and overall beneficial impact on the Tajikistan electricity system. The government’s choice of a higher dam height was justified despite the higher resettlement impact due to several key factors:
Economic Benefits: The highest dam option (335 meters) was found to provide the largest system cost savings and overall economic benefits. The economic analysis showed that this option would have a significant positive impact on Tajikistan's electricity system, making it the most beneficial in terms of energy generation and cost efficiency.
Technical and Dam Safety considerations: The TEAS concluded that the highest dam option could be built and operated within international safety norms, provided that specified design modifications and mitigation measures were implemented. This option was technically justified considering the long-term safety and operational efficiency of the dam.
Environmental and Social Impact Mitigation: Although the highest dam height would result in a larger number of resettlements, the ESIA identified measures to mitigate the impacts of involuntary resettlement. The resettlement plans included compensation for lost assets, construction of replacement houses, and livelihood restoration measures to help affected households rebuild their lives in the new locations.
Sustainable life of investment: The highest dam option was also considered the most sustainable in terms of the long-term life of the investment. The sedimentation study estimated that the Rogun reservoir would have a lifespan of around 115 years, significantly reducing the sediment filling rate of the Nurek reservoir and ensuring continued river regulation for an extended period.
Trade-offs and sensitivities: The TEAS considered various trade-offs between the different dam height options, including financing risks, macro-economic implications, social and environmental impacts, and opportunities for institutional arrangements and mutual benefits among countries. The highest dam option generally showed the greatest benefit across most sensitivities, making it the preferred choice despite the higher resettlement impact.
In summary, the decision to opt for the highest dam height was based on a comprehensive evaluation of economic, technical, environmental, and social factors, with a focus on maximizing the overall benefits while implementing measures to mitigate the resettlement impacts.
The Government acknowledges that the choice of a higher dam will result in increased physical and economic displacement around the dam and the reservoir and commits to identifying and providing choices for suitable resettlement sites, drawing on consultations with PAPs and taking into account safety and land-based livelihoods. To the extent possible, the government will also avoid resettlement, particularly amongst the communities which are further away from the inundation zone.
The Rogun Financing Options Study, completed by the World Bank in 2021, further assessed these dam height options and confirmed the rationale for selecting the tallest height. The study highlighted that the tallest dam option (335 meters) would yield the largest system cost savings and provide the most significant benefits in terms of energy generation and economic impact. The tallest height was selected because it maximizes the hydropower potential, ensuring a longer lifespan for the reservoir (100+ years) due to reduced sedimentation rates and providing enhanced flood protection downstream (thus providing enhanced protection to Tajikistan and riparian countries from increased flood risks resulting from climate change impacts). Additionally, the tallest dam height supports the strategic goal of exporting surplus electricity to neighboring countries, thereby enhancing regional energy security and cooperation.
2. Decommissioning
The financing options study concluded that, with over a third of the project already completed, decommissioning and mitigation of risks to the Vakhsh cascade would involve substantial additional costs and investments needed to replace the energy expected to be generated by the Rogun HPP, and result in significant foregone revenues from electricity exports, making non-completion a non-viable option at this stage.
3. Alternative Technologies: Solar and Wind
Extensive regional modelling work carried out by the World Bank during the project appraisal demonstrated that the Rogun HPP stands out as the least-cost solution for providing clean and affordable baseload electricity to Central Asia. The project is designed to significantly increase the supply of renewable energy, thereby reducing reliance on fossil fuels and supporting the region's low-carbon development goals. According to a regional planning analysis, the Rogun HPP, along with other large-scale hydropower projects, is expected to displace gas and coal-fired generation and provide stability services to further enhance the development of variable renewable energy sources like solar and wind.
The cost of electricity generated by Rogun HPP remains highly competitive compared to alternative baseload sources, making it a part of the least-cost supply options for both Tajikistan and the broader Central Asian region. This is crucial for meeting the increasing power demand and supporting economic growth and development aspirations of the region. Additionally, the project's ability to export surplus electricity to neighboring countries like Kazakhstan and Uzbekistan further underscores its role in enhancing regional energy security and cooperation.