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Tidal power is often dismissed as damaging to wildlife, but a large-scale review of evidence shows its effects are often neutral or even beneficial

For decades, fears about the ecological impacts of tidal power have hindered the development of one of the UK’s most reliable renewable energy sources. Despite its promise as a clean, predictable and long-lasting form of power generation, tidal energy has been overshadowed by concerns about damage to marine ecosystems and disruption to coastal environments. 

A new study led by researchers at 911½ñÈÕºÚÁÏ offers a different perspective. Its conclusions challenge some of the most persistent assumptions surrounding tidal power as lacking evidence and highlight how recent designs and construction processes have improved, as well as the potential benefits tidal barrages have for adapting to rising sea levels. 

The study, authored by Sylvia Ascher and Iris Gray, Research Assistants at the Centre for Sectoral Economic Performance in the Dyson School of Design Engineering, and Dr Tilly Collins from the Centre for Environmental Policy, reviewed more than 50 scientific papers examining the environmental impact of tidal power projects in Europe, Asia and North America – making it the most comprehensive review to date. 

Reassessing the evidence 

The researchers found that while tidal barrages and tidal flow turbines do alter local hydrodynamics and sediment movement, the widespread fears about lasting ecological harm are not substantiated by evidence. Many impacts observed in the 1960s to 1980s were linked to outdated construction practices, such as completely sealing off estuaries during building, which led to poor water quality, disrupted habitats and shifts in species composition. 

Their review highlights that bodies of water contained within tidal barrages, including those at France’s la Rance and South Korea’s Sihwa Lake (pictured), have achieved stable and enriched ecosystems over time. Life has flourished, with greater diversity and abundance of species and improved water quality recorded. 

They also reported studies showing that concerns about underwater ‘windmills’, known as tidal flow installations, harming animals are generally unfounded: fish and marine mammals tend to avoid turbines rather than collide with these, and monitoring shows no evidence of population decline or habitat fragmentation. 

“The evidence shows that the ecological story of tidal energy is more balanced than many assume,” said Dr Collins. “Changes do occur, most are manageable, and the habitats behind barrages can become wildlife-rich ecosystems.” 

Local changes occur, including shifts in sediment patterns, altered tidal range and changes in species distribution, but are not uniformly negative. In many circumstances, tidal energy infrastructure has been shown to generate positive ecological effects such as creating new habitats, improving water circulation and even restoring degraded environments. 

 Lessons from the past, opportunities for the future 

The authors emphasise that early tidal projects provided valuable lessons in both ecological management and engineering design.  

“Prior projects such as la Rance, Sihwa Lake and Kislaya Kuba in Russia give decades of information,” said Dr Collins. “Modern engineering techniques and better ecological understanding mean we can now design tidal systems that work with natural processes rather than against them.” 

Maintaining a tidal regime as close as possible to its natural state has proven key to minimising adverse effects, while careful site selection and adaptive management are essential to ensuring ecological balance. 

 A dual role in climate resilience 

Beyond its contribution to low-carbon energy, the study argues that tidal infrastructure could play a vital role in helping coastal regions adapt to climate change. With sea levels rising and storm surges becoming more intense, the potential for tidal barrages to act as both power plants and protective barriers offers a compelling case for reconsidering the technology. 

Modern designs can integrate flood control, habitat creation and renewable energy generation within the same infrastructure – a combination that aligns with the urgent need for resilience and sustainability in coastal management. The researchers highlight that tidal barrages, which can operate for more than a century, represent a long-term investment not only in clean energy but also in environmental protection and security for vulnerable communities. 

“Tidal barrages present a unique and valuable opportunity for addressing some of the most pressing challenges of our time,” said Dr Collins. “With careful planning, design and policy support, they could help the UK build resilience to rising sea levels while contributing to a sustainable energy future.” 

Researchers say that the UK, with its extensive coastline and tidal range, possesses substantial untapped potential and that tidal energy could meet up to 20% of the nation’s electricity demand while contributing billions to the economy. Yet, progress has been stalled by ecological concerns, high upfront costs and a complex regulatory landscape. 

By clarifying the true ecological footprint of tidal power, this study provides an evidence base for more balanced decision-making and renewed exploration of tidal projects as part of the UK’s renewable energy mix. 

 Informing policy and practice 

The researchers call for policymakers to recognise the dual benefits of tidal power, as a clean energy source and as a tool for climate adaptation, and to incorporate these co-benefits into planning and investment frameworks. They argue that clearer, evidence-based guidance on environmental effects could streamline approvals for new projects and encourage responsible innovation in the sector. 

The study also underscores the importance of long-term ecological monitoring and adaptive management. Continuous observation of tidal sites, using modern data collection and modelling techniques, will be crucial to ensuring that new developments avoid the pitfalls of the past and continue to operate harmoniously with their surrounding ecosystems. 

“Our review makes clear that the barriers holding back tidal power are no longer scientific,” said Dr Collins. “The technology is ready, what’s needed now is the policy vision and investment to unlock its full potential.” 

By integrating environmental evidence with engineering innovation, the researchers suggest that tidal power could emerge not as an ecological risk, but as part of a holistic response to the intertwined challenges of energy security, climate change and coastal protection. 

The paper (DOI: 10.1002/2688-8319.70124).