Forward flow
What it takes to achieve truly sustainable hydropower solutions
Elon Hägg
Martin Fuchs
Kenneth Ross
Hydropower is a fundamental renewable energy source with the potential to support a decarbonised and resilient energy system. It takes significant experience to understand the many factors involved and even more to connect and manage them sustainably. By focusing on key areas, hydropower projects can balance environmental and social impacts while delivering reliable, renewable energy.
Scaling renewable energy capacity
Scaling renewable energy capacity
Hydropower remains the world’s largest renewable energy source, contributing 37% of global renewable capacity in 2022 and growing to a total installed capacity of 1,412 GW in 2023. Its strategic importance lies not only in its scale but also in its ability to provide critical flexibility for energy systems worldwide, particularly in regions with high shares of variable renewable energy (VRE) such as solar and wind. Reservoir hydropower and pumped storage play a vital role in balancing energy supply fluctuations, reducing dependence on fossil-based generation, and ensuring grid stability.
Globally, hydropower’s potential continues to grow, with a required expansion of 26 GW per year through 2030 to meet Net-Zero targets. By 2050, doubling global hydropower capacity will necessitate cumulative investments of approximately US$3.7 trillion, or about US$130 billion annually. As the energy transition accelerates, hydropower’s inherent flexibility and capacity to store over 90% of the world’s stored energy underscore its unparalleled value in achieving a balanced, resilient, and sustainable energy future.
How to make hydropower even more sustainable?
Hydropower is the most mature renewable energy source on the planet. However, its environmental and social footprint was questioned from the 1980s to 2000s by series of poorly implemented projects. Today, the hydropower industry, driven by rigorous international standards, has raised its sustainability practices to prioritise healthy ecosystems, prosperous communities, and active stakeholder engagement throughout project life cycles.
For instance, environmental impact assessments (EIAs) and carbon footprint analyses are now integral to project planning, with special attention given to potential greenhouse gas emissions from reservoirs. Approaches like removing biomass before impoundment and optimising reservoir design help minimise methane and CO₂ emissions, particularly in tropical environments. This careful planning reduces ecological disturbances, aligning hydropower operations with global climate goals.
Hydropower's impact on local communities is equally significant. To foster positive outcomes, early engagement with stakeholders ensures projects are tailored to support community needs. Social impact strategies include job creation, infrastructure development, and sustainable practices that preserve cultural and natural resources, making hydropower projects beneficial for all.
Adaptive design for climate resilience
In the future hydropower and multi-purpose dams will also play an important role in adapting to climate change, e.g. in mitigation of flood and droughts. A common challenge is the possible but still uncertain increase of flood magnitudes under warmer climate conditions. Spillways can be designed in a way that they can be increased in capacity at a later stage without the need for major modifications to the concrete structures. This approach is called adaptive design which will become relevant also for other infrastructure exposed to uncertain impacts of climate change.
Hydropower plants themselves also need to be designed in a sustainable way. To minimise greenhouse gas emissions associated with construction, the design should be optimised on the basis of carbon footprint assessments, varying parameters such as general layout, dam type, amount, and type of material used. During dam operation, substantial amounts of greenhouse gases might be emitted from the reservoir (methane, CO₂), especially in tropical environments. This can be mitigated by proper reservoir design, removing of biomass prior to impoundment, and adjustments in reservoir operation. Hydropower design must also be climate resilient, e.g. easily adaptable to changes in climate and hydrology. This applies to power generation (installed capacity) as well as to flood management and dam safety.
Aquatic life
Hydropower projects can disrupt aquatic ecosystems by blocking fish migration paths and altering sediment flows, making biodiversity preservation essential. For run-of-river plants, effective solutions for upstream fish migration, such as fish passes and fish lifts, have been implemented. Meanwhile, innovative fish-friendly turbine designs are under development to enable safe downstream migration, an area of active research and advancement.
Sediment flow management is another priority, as hydropower reservoirs often trap sediments, reducing capacity and impacting downstream ecosystems. Active sediment management practices, including upstream erosion control and regulated sediment transport, help maintain both reservoir function and downstream habitat quality. Together, these measures help reduce the long term environmental impact of hydropower projects, supporting overall ecosystem health
Huge projects – how to manage all variables?
New hydropower plants can be huge projects both in terms of scale of the construction but also in the amount of people working at the site – sometimes these will be measured in tens of thousands of workers at a site. That is why managing large hydropower projects can be challenging, in terms of the human factor as well as the delivery of the design and construction supervision needs of the project.
This is true for almost any large-scale project, no matter the industry. At AFRY, the strategy is to always build one solid and united team who bear the difficulties of the environment and the need for speed in the execution of the project to meet the sometimes very tight milestones demanded from the construction contracts and our clients.
Managing the construction contractors, of which there can be many on each individual project, is also a challenge. We have to be realistic and fair in our requirements and instructions, while considering, for example, that the labour and materials necessary for the construction can travel thousands of kilometres to the site. We always consider the sensitivities of the multicultural and diverse teams we have on sites, not only within AFRY, but within the contractors’ personnel we work
with as well.
Electricity capacity trends (MW)
Modern, sustainable hydropower
A modern hydropower development simply has to meet very high technical and socio-environmental standards. Sustainable hydropower goes beyond technology, integrating design, project execution, site management, and environmental stewardship. With hydropower’s crucial role in renewable energy, ongoing advancements, and adaptive designs will ensure it meets future challenges, supporting both ecological balance and energy needs. Looking ahead, hydropower’s evolution will continue to drive sustainable energy solutions globally.
Nam Theun 1
Hydropower project in Laos
The Nam Theun 1 Hydropower Project in Laos has an installed capacity of 650 MW, of which a total of 520 MW is exported to Thailand and 130 MW is available for domestic consumption.
The Project includes a 187 m high curved RCC gravity dam on the Nam Kading River, a single power waterway with low and high pressure tunnels, and two shaft powerhouses.
AFRY’s role included the provision of consultancy services across all project stages from the development through to the feasibility and all design phases, as well as site supervision services during project execution and commissioning (from 2013 to 2022).
The team was diverse and multicultural, made up of close to 60 persons, with 14 different nationalities, arriving to work on the project from six continents across the world.
The team were all residing on the construction site in Laos when the COVID-19 pandemic arrived, and they all had to remain on the site with local and international borders closed for approximately 18 months. The AFRY team formed a unique bond, successfully enduring the situation together, and rather than feeling dejected, they broke numerous world records in dam building with the contractors and the client and left a unique legacy to pass on to the generations of engineers to come.
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