Sylvia Ascher: Misplaced fears? What the evidence reveals of the ecological effects of tidal power generation

About the research

Overview

Our paper focuses on understanding whether the ecological fears surrounding tidal energy are actually backed by evidence. Tidal power is a reliable, clean, and predictable renewable energy source, yet projects are frequently delayed or cancelled due to concerns about environmental harm. We systematically reviewed the empirical literature, 54 papers spanning decades, covering both tidal range (barrages) and tidal stream (turbines) technologies. We wanted to see whether the widespread concerns about effects on marine life, sediments, water quality, and habitats were substantiated by data or whether they were, in many cases, misplaced.

Surprises and challenges

We were surprised by how many widely-held concerns turned out to be unsubstantiated by evidence, or, where effects did exist, how often they were neutral or even positive. For instance, the La Rance barrage basin is now designated a wetland of international importance for waterbirds. One challenge was the scarcity of literature: only 54 relevant empirical papers existed across all major tidal projects globally. The evidence base is thinner than the public debate might suggest.

Next steps and broader implications

Now that there’s growing public awareness that many of the ecological fears around tidal power are unsubstantiated, there’s been a real surge of interest in the UK, in policy circles, industry, and among researchers. The conversation has shifted in an exciting way: rather than simply asking “how do we avoid harm?”, people are starting to ask “what are the co-benefits?” There is now active research into how tidal energy infrastructure might deliver ecosystem benefits alongside clean power generation.

The UK has among the world’s largest tidal energy resources, and marine renewables could realistically contribute a very significant share of our electricity needs. That has huge implications, for spatial planning, and for how we think about grid integration, since tidal energy is predictable in a way that wind and solar simply aren’t. Our research helps provide the evidence base that planners, developers, and policymakers need to move forward with greater confidence, and to do so in a way that is genuinely informed by what the science actually shows, rather than by longstanding assumptions that haven’t been properly tested.

About the author

Current position

I currently work at an environmental and social impact research consultancy, primarily with NGOs on topics related to nature and climate governance. One project I’m particularly excited about right now is exploring the value of UK seaweed, which has brought me right back to thinking about the exciting and undervalued potential of our coastlines. It feels like a very natural continuation of the themes in this paper: that marine environments are deeply misunderstood and too often undervalued, when in reality they have so much to offer.

Getting involved in ecology

Growing up on the west coast of Canada, I was surrounded by some of the most spectacular natural environments in the world. Hiking, swimming, skiing – being outdoors was just part of life, and it gave me a deep, instinctive love of the natural world from a very young age. That connection to the environment never left me, and it’s really what has driven everything since, the desire to understand natural systems better, and to find ways to protect them.

Is the research ongoing?

Following this phase of the research, a second phase focused on understanding potential co-benefits from tidal barrage development beyond energy generation – specifically their role in coastal flood protection, habitat conservation, and climate resilience. We mapped key UK coastal characteristics, including tidal range, conservation areas, sea-level rise projections, and population density, to identify sites where barrages could deliver the greatest combined ecological and socioeconomic benefits, and to highlight previously proposed sites for reassessment. With this new evidence suggesting that the ecological impacts of tidal barrages have long been overstated, there is substantial further research to be done around how this technology can be developed responsibly and to its fullest potential.