June 4, 2010 - tidal power in Maine, a history, part 1

Friday, June 4, 2010

Humans have harnessed the mechanical energy of tidal fluctuations for a long time -- at least as far back as the Romans in 600 A.D., and possibly as early as 200 A.D. The exact mechanisms vary, but the basic idea is to convert the potential energy of water that has been lifted by a high tide as it falls to a lower elevation. Typical sites are on tidal estuaries or rivers: sheltered from the effects of open ocean waves, but salty enough to have a significant tide.

Tide mills were common in Maine, especially just downriver from my house in Bath. At Winnegance, on the Bath-Phippsburg line, a bend in the Kennebec River with a natural cove made for optimal conditions for tidal power.

The History of Phipsburg, Maine, from George Varney's 1886 A Gazetteer of the State of Maine, describes some of the local resources:

At the north looms Parker’s Head, and at its south-western side is the inlet basin forming the tide-power known as Parker’s Head Mill Pond. Next succeed the harbor at Phipsburg Center, with Drummore Bay two miles above, with inlet and tide-power. Through Fiddler’s Reach, a curve of the Kennebec around the northern end of Phipsburg, we pass to Winnegance Creek, nearly three miles in length, and a basin at its extremity, forming two unsurpassed tide-powers, and separating Phipsburg from Bath and from West Bath except for a neck 200 rods in width, the Winnegance Carrying Place.

The History gives more detail on the Winnegance mills:

On the Winnegance Tide-Power, three miles from Bath post-office, and four miles from Phipsburg Center Village, have been sixteen mills, nine on the Bath side and seven on the Phipsburg side of the line. Some of these, however, were burned several years since. There are now ten sawmills and one grist-mill operating in the town.

So why Winnegance? The site was right, in that the coves and tide range were ideal. Furthermore, the site was near the mouth of the Kennebec River, where millions of logs floated downriver every spring and summer for processing into lumber, and loading onto schooners to send the boards to markets around the world. Many of the older houses in the Winnegance and Bath area, ours included, bear the marks of the kind of up-and-down tide-powered saws that operated there.

I'm curious to learn more about why tide mills largely vanished. (At Winnegance, the Morse & Sons Lumber mill still operates where the Morses have run it since 1801, but it no longer apparently harnesses the tides.) An interesting piece in Discover Maine Magazine points to the inconvenience of the timing of tidal power. If you are limited to tapping the ebb flow, the time of the peak drop will move -- at Winnegance, each high tide is 12 hours, 22 minutes later than the previous -- so some days, your power resource will only really be operative at night. I'm not sure this was enough to eliminate most of the tidal power development in Maine, but it was a start.

I'm also going to look at more ambitious historic tidal power plans like the Passamaquoddy Power Project.

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