As the world moves steadily towards a low-carbon future, hydroelectric power often emerges as a leading candidate in the global green energy portfolio.
But how sustainable is hydropower really? And can it continue to deliver clean electricity without compromising the environment?
Here, Haush examines the sustainability of hydroelectric power generation, from its renewable credentials to its environmental impact, efficiency, and economic viability. We’ll also explore regional examples from the UK, Europe, and beyond, alongside current electricity generation costs across continents.
What is Hydroelectric Power and Why Is It Considered Green?
Hydroelectric power is a form of renewable energy that uses the gravitational force of flowing or falling water to generate electricity, typically via dams or run-of-river systems. It is classified as green energy due to its low carbon footprint, high efficiency, and ability to supply base-load and peak-load electricity with consistency.
According to the International Renewable Energy Agency (IRENA), hydroelectric power has a lifecycle greenhouse gas emission rate of around 24g CO₂-eq/kWh, significantly lower than fossil fuels and even lower than solar PV or biomass.
The Sustainability Credentials of Hydroelectric Power
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Renewable and Low Carbon
Hydropower harnesses the Earth’s natural water cycle, making it inherently renewable. The consistent nature of water flow, especially in mountainous or high-precipitation regions, ensures long-term viability. Unlike fossil fuels, it emits minimal greenhouse gases over its lifecycle.
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High Efficiency and Grid Reliability
Hydroelectric plants are among the most efficient power generators, with efficiencies exceeding 90%, far surpassing coal (~35%) and even solar PV (~20%). Their ability to respond quickly to electricity demand changes makes them indispensable for grid stability, especially when complementing variable renewables like wind and solar.
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Cost-Effective Long-Term Investment
Though capital-intensive to build, hydroelectric systems offer decades of low-cost energy production. Once operational, they incur minimal fuel costs, translating into some of the lowest levelized costs of electricity (LCOE)among all energy sources.
Environmental Considerations: The Other Side of the Coin
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Impact on Ecosystems and Fish Migration
Large dams can alter river ecosystems, impede fish migration, and disrupt sediment flow. In the UK, projects often require Environmental Impact Assessments (EIA) and fish ladders or bypass systems to reduce ecological harm.
For instance, the Glenlee Hydropower Station in Scotland, part of the Galloway Hydro Scheme, has incorporated modern fish passage technologies to minimise impact on salmon and trout populations.
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Land Use and Habitat Loss
In countries like Norway and Switzerland, reservoirs are built in already sparsely populated mountainous areas, reducing human displacement. But globally, projects like the Belo Monte Dam in Brazil have drawn criticism for flooding large swaths of forest and displacing indigenous communities.
In the UK, smaller run-of-river schemes like the Osney Lock Hydro in Oxford have grown in popularity for their low land-use footprint and minimal disruption to local biodiversity.
Hydroelectric Power in the UK and Europe: Examples and Expansion
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The UK
Hydropower accounts for a small but significant portion of the UK’s renewable mix (~1.5%). Notable examples include:
- Dinorwig Power Station (Wales): A pumped storage facility capable of delivering power to 1.5 million homes in just 16 seconds.
- Foyers Hydro Scheme (Scotland): A pumped storage plant in the Highlands using Loch Mhor and Loch Ness.
- River Dart Hydro (England): A small-scale community project that demonstrates how hydropower can serve rural needs sustainably.
Due to limited topography, the UK’s growth potential lies mainly in micro-hydro schemes (up to 100 kW), which are particularly suited to Scotland, the Lake District, and Wales.
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Continental Europe
Europe is a hydroelectric powerhouse, especially in alpine and Nordic nations:
- Norway: Generates over 90% of its electricity from hydropower. Its mountainous terrain and abundant water make it ideal for large-scale generation.
- Austria and Switzerland: Depend heavily on hydropower, with projects like the Kaprun Hydro Plant (Austria) and Grande Dixence Dam (Switzerland).
- France: Home to the Génissiat Dam on the Rhône River and over 400 other hydro plants.
- Portugal: The Alqueva Dam not only produces electricity but also supports irrigation and water supply in the Alentejo region.
Global Comparison: The Cost of Hydropower by Region
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Region
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Average Cost of Hydropower (USD/kWh)
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Notes
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|---|---|---|
| UK | $0.07–$0.11 | Depends on the scheme size and site |
| Europe | $0.05–$0.12 | Cheaper in Alpine/Nordic regions |
| USA | $0.03–$0.09 | Large-scale projects dominate |
| Canada | $0.02–$0.07 | Extremely low costs in Québec |
| Brazil | $0.04–$0.06 | Hydropower dominates the national grid |
| Vietnam | $0.045 | Government-subsidised rates |
| Indonesia | $0.067 | Small hydro gaining traction |
| South Africa | $0.08–$0.13 | Mostly small-scale, seasonal sources |
These figures are based on estimates from IRENA, IEA, and national energy agencies. Hydropower remains one of the most cost-effective renewable energy sources, particularly when natural geography supports it.
Innovations Making Hydropower More Sustainable
Modern innovations are helping reduce hydropower’s ecological footprint:
- Fish-friendly turbines: Developed by companies like Natel Energy in the US.
- Sediment management systems: Maintain reservoir capacity and river health.
- Floating solar-hydro hybrids: Projects in China and India combine hydropower with floating PV systems on reservoirs.
A Green Giant with Room to Grow (Responsibly)
Hydroelectric power remains a cornerstone of sustainable energy. Its ability to provide reliable, renewable, and cost-effective electricity makes it a vital player in the global energy transition. However, careful planning, ecological safeguards, and a shift towards low-impact systems will be key to ensuring its long-term sustainability.
From the mountains of Norway to the streams of the Scottish Highlands, hydropower continues to demonstrate that green energy can be both powerful and practical when harnessed responsibly.
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