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Hydropower is often advocated as a sustainable and environmentally friendly energy source that can help decrease dependence on fossil fuels. However, the construction and operation of hydroelectric dams can have significant environmental impacts, such as disrupting aquatic ecosystems and displacing local communities. As the world seeks to increase its hydropower capacity to meet growing energy needs, finding a balance between energy production and environmental preservation is essential.
The Promise of Hydropower
Hydropower is currently the largest source of renewable electricity generation worldwide, accounting for over 60% of all renewable power. It offers several advantages over other energy sources.
- Renewable and emissions-free: Hydropower taps into the natural water cycle to generate electricity without producing greenhouse gases or other air pollutants
- Flexible and reliable: Hydroelectric plants can quickly adjust their output to meet fluctuating energy demands and provide grid stability
Long Lifespan: A Reassuring Investment in the Future many hydropower facilities have operating lifetimes of 50 to 100 years, providing a long-term solution to our energy needs. These benefits have made hydropower an attractive option for countries expanding their renewable energy capacity. The Philippines, for example, has set a target of increasing its hydropower capacity from 3.5 GW to 8.5 GW by 2040 as part of its push for cleaner energy.
Environmental Impacts of Hydropower
However, hydropower projects can also have significant negative impacts on the environment:
- Disruption of aquatic ecosystems: Dams can block fish migration, alter water temperatures and chemistry, and change natural flow patterns, harming native species
- Displacement of local communities: Reservoirs created by dams often flood inhabited areas, forcing people to relocate
- Greenhouse gas emissions: While hydropower itself is emissions-free, the manufacturing of concrete and steal for dams can produce significant amounts of CO2
- Sedimentation and erosion: Dams can trap sediment, depriving downstream areas of nutrients and causing erosion
These impacts can be particularly severe in ecologically sensitive areas like the Yangtze River basin in China or the Tigris-Euphrates basin in the Middle East, where multiple dams are planned or under construction.
Mitigating Environmental Risks
Hydropower projects must incorporate measures to mitigate environmental risks:
- Careful Site Selection: A confident step towards responsible development, avoiding areas with high biodiversity or cultural significance can minimize impacts and ensure the responsible development of hydropower projects.
- Environmental impact assessments: Thorough studies of a project’s potential effects on the local ecosystem and community are essential before construction begins
- Fish ladders and elevators: These structures help migrating fish bypass dams and reach their spawning grounds
- Minimum environmental flows: Maintaining adequate water levels downstream helps sustain aquatic life and prevent the standing of fish and macroinvertebrates
- Ramping rules: Gradually increasing or decreasing water releases from dams can reduce the impact on riverbanks and aquatic organisms
- Sediment flushing: Periodically releasing water to flush out accumulated sediment can help maintain downstream habitats
Implementing these measures requires close collaboration between hydropower developers, environmental agencies, and local communities. In Cebu, for example, the provincial government is working with the National Power Corporation to ensure that the planned 741 MW Cebu Wind Power Project incorporates measures to protect the local environment and community.
The Role of Pumped Storage Hydropower
One promising approach to balancing energy and environmental concerns is pumped storage hydropower (PSH). In a PSH system, water is pumped from a lower reservoir to an upper reservoir during periods of low electricity demand and then released through turbines to generate electricity during peak demand.
PSH offers several advantages over conventional hydropower:
- Flexible and efficient: PSH plants can quickly adjust their output to meet fluctuating energy demands, making them ideal for integrating variable renewable sources like solar and wind.
- Reduced environmental impact: By recycling water between reservoirs, PSH minimizes the need for large dams and reservoirs that can disrupt aquatic ecosystems.
- Long Lifespan and Low Maintenance Costs: Compared to other energy storage technologies, PSH facilities have a 50- —to 100-year lifespan and relatively low operating and maintenance costs.
As of 2020, global PSH capacity stood at around 160 GW, with significant potential for further growth. Developing PSH projects with other renewable sources like solar and wind can help create a more sustainable and resilient energy system.
Sustainable Hydropower
Hydropower is vital in transitioning to a clean energy future, but it must be developed to minimize environmental and social impacts. By carefully selecting project sites, conducting thorough ecological assessments, and implementing effective mitigation measures, hydropower developers can help strike a balance between energy and environmental concerns.
Pumped storage hydropower, in particular, offers a promising path forward by providing flexible, emissions-free energy storage while reducing the need for large dams and reservoirs. As countries like the Philippines continue to expand their hydropower capacity, they must prioritize sustainability and work closely with local communities and environmental agencies to ensure that these projects are developed responsibly and with the planet’s long-term health in mind.