New Life for Old Tide Mill Sites?

A Belgian company named Turbulent has developed turbine systems requiring a head of only 5 feet (1.5 meters) and a flow of only 53 cu. feet/second (1.5 cu. meters/second) to generate a useful amount of electric power, according to company literature. The systems are also compact and relatively simple to install, which could make them suitable for installation at former tide mill sites, where water height difference is determined by tidal range at the site. Such installations could produce 15 kW or more as distributed energy sources.

Turbulent’s vortex turbines extract energy from water falling vertically from an input basin shaped to create a swirling low-pressure flow (low pressure vortex) before the water enters the turbine. The company says installations do not obstruct normal water flow and let “all fish and aquatic life pass by unharmed.”

In addition to the turbine, the core unit contains a gearbox and high efficiency generator. Turbines are available with impeller diameters from 51 inches (1.3 meters) to 75 inches (1.9 meters) and with power output capacities from 15 kW to 70 kW.

Vortex turbine with integral gearbox and generator. (Courtesy of Turbulent.)
Actual vortex turbine installation in Chile, operational since 2018. (Courtesy of Insider Tech.)
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Some Tide Mill History – And a Call for Small-Scale Tidal Power

Cover of the 2005 publication, Ocean Sciences Bridging the Millennia.

A 2005 paper by Roger H. Charlier, Lo’ic Menanteau, and Marie-Claire P. Chaineu was recently brought to the Tide Mill Institute’s attention by Dutch sculptor and artist Lex Elsevier. The paper presents “an overview of tide mills throughout the world with emphasis . . . on recent research in the Iberian Peninsula, from the Basque Country in the North to the Gulf of Cadiz in the South, and the restoration of several mills in Brittany (France) over the last decade or so.”

Tide mill enthusiasts will enjoy reading this 18-year-old report not only for the historical information it contains, but also for its call to resurrect small scale tide mill sites for providing power locally. These days, the idea of exploiting smaller energy sources for local consumption is called distributed generation.

“The Rise and Fall of the Tide Mill,” appeared in Ocean Sciences Bridging the Millennia. A Spectrum of Historical Accounts published by the Journal of Coastal Research.

Read “The Rise and Fall of the Tide Mill” courtesy of the Flemish Marine Institute (VLIZ. be).

Postponed – Oct 28 Tide Mill Conference

The 2023 tide mill conference scheduled for October 28, 2023, has been postponed until the spring of 2024.

Leadership of the Tide Mill Institute regrets this last-minute postponement, but decided it is prudent because of ongoing emergency conditions in parts of Maine and out of respect for the victims of the tragic mass shooting in Lewiston on October 25. The suspect in the shootings is still at large and may be in the region.

The conference will be rescheduled for the spring of 2024 and notice will be sent when a date has been chosen. Those who used a credit card to pay the registration fee for the October 28, 2023, conference will see a refund to their credit card account within a few days. Those who paid by check will have their check returned.

Tide Mill Institute extends condolences to the families and loved ones of the October 25 victims and is grateful for the ongoing efforts of law enforcement agencies to protect the public and apprehend the suspect.

Join Us for the 2023 Annual Tide Mill Conference

Registration has opened for the 2023 annual tide mill conference: “Harnessing Tides for Energy and Agriculture.” This year’s conference will convene at the brand-new McGoldrick Center at the University of Southern Maine in Portland. The conference is scheduled for Saturday, October 28, from 8:30 a.m. to 12:30 p.m. Eastern Daylight Time (12:30 to 16:30 UTC).

Join other tide mill enthusiasts and scholars in-person or online (via Zoom conferencing) to participate in talks about a recent archeological study of tide mill ruins, the history of a 20th century proposal to harness the tides in Passamaquoddy Bay, future tidal energy initiatives worldwide, and the impact of 17th-century dykes along the shores of Bay of Fundy in today’s Nova Scotia from the time of their construction to the present.

The conference fee is $25, payable online or by check.

Conference postponed until spring, 2024

McGoldrick Center for Career & Student Success, University of Southern Maine.
How an aboiteau worked to drain and reclaim tidal marshes for agriculture. (Diagram by Kirill Borisenko/Wikimedia Commons, CC-BY-SA-3.0.)

Appreciating Tide Mill Art

British film maker and writer Colin Collis generously offered Tide Mill Institute photographs of two tide mill paintings by Victorian artist Alfred Omega Townsend (1845-1917) for posting on the TMI website. Information about the subject, a tide mill in Falmouth, England, is scarce, but a 2005 report about Falmouth by the Cornwall & Scilly Urban Survey project speculates that the tide mill probably was established in the late 1600s and ceased operation in the 1860s. Remains of the mill pond walls were examined as recently as 1988 when the area was developed as a marina.

Thanks to Collis and the Falmouth Art Gallery, we’re able to share three contemporaneous images of the mill. All were painted while the decaying structure still stood: the two below by Townsend and a third by William J. Boase Smith (1842-1896). The Smith painting, “The Old Bar Mill/The Old Bar Pool,” hasn’t been cleared to post directly on the TMI site, but it can be viewed on the art gallery’s website by clicking here.

One might wonder how many other examples of tide mill art exist in museums, galleries and private collections. If you know of any, please contact Tide Mill Institute. If possible, we will share them with our followers.

Falmouth tide mill circa 1890 by Alfred Omega Townsend. Courtesy of Colin Collis. ©Colin Collis.

Falmouth tide mill circa 1898 by Alfred Omega Townsend. Courtesy of Colin Collis. ©Colin Collis.

Saw Blade Mystery Resolved

by Harry Hopcroft, Tide Mill Institute

Saw blade at Georgetown (Maine) Historical Society’s 2023 exhibit.

When the circular saw blade on display at this summer’s Georgetown Historical Society exhibit was closely examined, it was found to have an extra plate mounted in the center, and on only one side. The extra piece is severely rusted in place now, but was originally held on by a series of short machine screws installed through holes from the back side of the blade. It is about a third to half the diameter of the main part of the blade, and thicker at the spindle than at its edges. The main blade itself is about 1/8 inch thick, and the added piece is ½ inch thick at the spindle, then tapers to almost knife edge at the outside. The main blade also has very little “kerf”, which is the measure of the width of the cut. The kerf is created by bending the cutting teeth outward in an alternating pattern from one side to the other. That allows the blade kerf to be a tiny bit wider than the thickness of the blade, and helps prevent the saw from binding.

The sort of obvious answer was that the extra piece was there to stiffen the blade, but it also appeared that it would severely limit the depth of the cut available with this blade, so we wondered why it was added. We knew the blade came from the site of the Oliver Grist and Shingle mill on the west end of the dam in Georgetown Center, so presumed it had something to do with cutting shingles, not logs.

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