No barrage-type tidal energy projects have been initiated in 25 years, mostly due to concerns about high construction costs and fears of negative ecological effects. While construction costs continue as a roadblock for such projects, some negative ecological effects now taken for granted might be “misplaced fears.”
That’s one of the conclusions of a study published in early October in Ecological Solutions and Evidence, a journal of the British Ecological Society. Titled “Misplaced fears? What the evidence reveals of the ecological effects of tidal power generation,” the study reviewed 54 articles related to tidal power system construction and operation and concludes that “few of the widespread [tidal energy ecological] concerns are substantiated by evidence or in long-term monitoring of existing projects.”
The study points out how objections to tidal power projects “often stem from perceptions of adverse ecological effects.” It states, however, that only a few of these adverse effects are backed by evidence or by long-term monitoring of existing tide power installations. What’s more, some projects may have positive ecological effects. The key to minimizing harmful effects, say the authors of the October study, is keeping a tidal regime similar to its original state.
The articles and papers reviewed in this study confirm that tidal projects can change hydrodynamics and sediment changes at barrage-type (tidal range) installations such as the LaRance station in France and the Annapolis Royal station in Canada. But many other objections to such projects “remain unsubstantiated” or have only neutral effects on marine ecosystems. Some positive effects identified are more productivity and greater species diversity in tidal range basins.
The study covers published papers related to the five “principal tidal barrages” now existing in the world:
- La Rance Tidal Power Station – France
- Sihwa Lake Tidal Power Station – South Korea
- Annapolis Royal Generating Station – Canada
- Kislaya Guba Tidal Power Station – Russia
- Jiangxia Tidal Power Station – China
The authors point out, however, that available data for ecological effects of tidal range power stations is limited and “substantially more nuanced than generally perceived.” This is because, they say, monitoring of these sites is poorly planned or inconsistent, even for stations that have been operating for many years.
The study also looks at tidal stream energy projects and notes how attention has shifted to this technology, which is rapidly advancing. The focus on tidal stream projects may partly be due to studies showing that tidal stream power systems are less ecologically disruptive than tidal range projects. But most tidal stream research, the study authors say, has been limited to single unit or small arrays. Therefore, the conclusion warns, scaling up tidal stream arrays might have a greater impact on local ecosystems.
The authors urge more focus on effectively balancing plausible ecological risks with “the considerable potential of tidal energy to contribute to sustainable energy production and thus climate change mitigation.”