Registration has opened for the 2026 tide mill conference being held in Fairfield, Conn., on Saturday, April 25. You can attend “Tide Mills of Long Island Sound” in person at the Fairfield Museum and History Center or on line via Zoom conferencing.
Long Island Sound has at least 24 identified historical tide mill sites on its shoreline and tidal inlets. This year’s conference focuses on selected sites on Long Island and the Connecticut coast. Join us for an outstanding slate of illustrated talks and discussions of tide mill history and tidal energy.
“Green hydrogen” is hydrogen gas produced by using renewable electricity to split water into hydrogen and oxygen with little or no carbon emissions. Now, a demonstration project at the European Marine Energy Centre (EMEC) on the island of Eday in Scotland’s Orkney Archipelago [Google Maps] uses tidal energy to supply the renewable electric power for the hydrogen-oxygen splitting process.
Electrolysis, the process employed by EMEC on Eday, is a well-known technology that conducts electric current through water to produce hydrogen. What’s different about the EMEC center is their source of electricity: a tidal turbine located about a mile (1.6 kilometers) offshore, where it generates power from the strong tidal currents in the region. The 243-foot (74-meter) O2 tidal turbine, built by Orbital Marine Power, is tethered to the ocean floor and floats on the surface, deploying two 33-foot (10-meter) rotors that extract energy from tidal current flowing past its stationary hull. (The O2’s power capacity is 2 megawatts, enough to power about 2,000 homes.)
Hydrogen gas EMEC produces can be used for powering hydrogen fuel-cell vehicles, a carbon-free transportation mode. Hydrogen can also be used for fueling rockets, producing ammonia for fertilizers, and for several other industrial processes.
EMEC hydrogen production and energy storage facility on the island of Eday. (Courtesy EMEC)O2 turbine generating power while anchored in powerful tidal currents. (Courtesy Orbital Marine Power)O2 tidal turbine configuration as captured from Orbital Marine Power’s interactive model. (Courtesy Orbital Marine Power)
Sihwa Lake Tidal Power Station in South Korea. It cost $560 million (USD) to construct and started operation in 2012. With an output capacity of 254 MW, it is the largest tidal power installation in the world (Wikipedia). (Image credit: Kimhs5400, CC BY 4.0, via Wikimedia Commons.)
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 picturesque town of Harpswell on Maine’s jagged coast was once home to up to 15 tide mills. Tide Mill Institute co-founder, architectural historian, and historic preservation expert John Goff recently gave a highly entertaining and educational presentation about these mills at the Bowdoin College Schiller Coastal Studies Center. Thanks to Harpswell Heritage Land Trust and Harpswell Community TV, a recording of his talk is now available on line. (To view, click the frame.)
John’s meticulous research covered many topics related to the Harpswell mills and tide mills in general. For viewers new to tide-powered mills, he explains tide mill operating principles and technology transferred from England to America, including mill stone designs, mill building features, and the grain milling process. He also provides economic, historical, and geographic context for these long-gone and almost forgotten structures. Never one to ignore the social side of the local milling industry, John also presents his recent findings about mill owner and operator genealogy.
Tide Mill Institute continues its mission of researching and cataloging historic tide mill sites and promoting the use of tidal energy as a sustainable power source. In the past year, we have accomplished the following:
Index card files, part of the Peveril Meigs tide mill collection transferred to the Maine State Library.
Transferred mid-twentieth century notes and papers of Peveril Meigs, tide mill researcher, to the Maine State Library.
Expanded our growing database of worldwide tide mill sites.
Built a consortium with Canadian researchers investigating seventeenth-century tide mill remnants in Maine and the Maritime provinces of Canada.
Collaborated with preservation organizations on several extant tide mill structures on the east coast of the U.S.
Organized and found a publicly-accessible home for the Bud Warren Collection of multi-decade tide mill research.
Worked with engineers, scientists, and the National Hydropower Association to investigate sites for future tidal power generation.
TMI is always looking for information (deeds, oral history, maps, physical remnants) about tide mill sites. Please contact TMI if you can help.
The 1877 Mill Springs Mill features a 40-foot steel waterwheel. (Photo courtesy of SPOOM.)
Our friends at the Society for the Preservation of Old Mills (SPOOM) urge you to register now for their Sept. 19th and 20th conference in Monticello, Ky., before the early registration discount expires on Aug. 15th. While no tide mills appear on this year’s conference slate, three historical fresh water mills and a 1940s hydro-electric station are on the schedule – in addition to two historical houses and the Wayne County Historical Museum.
For tour details and registration instructions, visit the SPOOM website (SPOOM.org).
