Current events

Back in the 1970s, there were schemes aplenty to harness the power in the tides of the Minas Basin. We were excited to think, after the “success” of the Annapolis Royal Tidal Power Generator, extraction of power from the tides in the Minas Channel could cut our power bill in half. This clean, reliable, endless source of energy could be converted to electricity and cabled to our homes!

That old dream of using natural forces lives on, whispering in the ears of those who live in hope and expectation. “What about the tides? Why not the tides?” Certainly a natural force, certainly reliable—we can predict them pretty much to the minute—and, as for endless supply, certainly available for the next few generations!

One by one, those dreams crumbled away. The tidal power cannot be harnessed on the old model of choking a river and mounting a turbine to spin in the overflow. At least, it can’t be done without paying too huge a toll in terms of the environment and the creatures which dwell there.

Tough choices lie ahead. Last year, both the CBC and The Chronicle Herald pointed out just about 9/10 of the fuel that powers us comes from outside the province. This leaves us “at risk for energy,” subject to erratic price fluctuations and supply breakdowns. Self-sufficiency rests on a platform supported by toothpicks. A mosquito landing in the wrong place could crush the toothpicks - or so some would caution us.

It’s no surprise some folks have been going along quietly looking into things: researching, problem solving, collaborating.* Around the world, 40 to 50 tide-powered turbines are in development. The complex currents of the Minas Channel have been monitored just recently; the channel bed, mapped to a two metre resolution.

The trick would be to find a perfect current combined with a place flat enough to mount one of those free standing turbines, like the Underwater Electric Kite, Clean Current Turbine or Open-Centre Turbine. The magic spot to mount a turbine would have a steady flow of water, not a whirlpool, nor turbulence.

A good spot would be where it would not interfere with sea creatures, plant or animal. The last thing anyone would want to do would be to alter the perfect environment for flounder or rockweed or disturb any relics of Mega Beaver.

Things like ice cakes, submerged logs and rolling boulders would be problems for a turbine; as would sand (tidal sand would rasp a turbine to dust in no time flat!) and clay.

Under consideration, too, is the length of the cable between the turbine and the grid, how to install it, how to raise it.

As for how many turbines could be installed without affecting the tides themselves, mathematicians at Acadia University estimate “over 2.5 Gw of power can be extracted with less than a 6% change the tidal amplitude at any location”.** 2.5 GW would power over 800,000 homes. * http://www.minas.ns.ca/tidal/index.html

http://www.minas.ns.ca/tidal/links.html ** http://www.siam.org/students/siuro/vol1issue1/S01006.pdf

See this site for environmental concerns around the Minas Basin: http://www.bofep.org/mpas.htm