So, here we sit, eating World Famous Digby Scallops beside the Bay of Fundy, home of the greatest tidal forces on the planet. Tides can range 50 feet from high to low. Billions of tons of water moving at almost 20 km/h every day, twice in, twice out. Humans have been using flowing water to power our endeavours for centuries. Millennia, even. Why aren’t we using this great natural resource? As usual, it ain’t that simple.
The Dirty Truth
There is an experimental tidal generating plant at Annapolis Royal. It has been producing enough power for 4,500 homes since the mid-eighties. But the experiment is not going to be repeated. Why? In a word, silt. This generator only turns in one direction. So water runs into the storage basin at high tide, then creates energy when it runs out as the tide drops. So the plant works even more efficiently if it is placed at the mouth of a river.
But waters with enough current to make electricity stir up silt. When you stop that water and store it for use during low tide, the silt drops out and fills up your storage basin. And while the Annapolis River is relatively clean, the other rivers that empty into the Bay of Fundy are thick with silt and can’t be used.
However, there is one spot that doesn’t need a river. The narrows in the Bay itself at Minas Passage have a huge potential using the tides alone. This is the area of the 50-foot tides. But no one can even experiment there, either. Why? Well, depending on who you ask, either ecology or politics.
Several months ago there was a proposal to put an experimental turbine in that pass, where the water flows at rates approaching 15 km/hr. Immediately there was an uproar. Fishermen and ecologists protested that putting turbines in that kind of flow would destroy the huge fish and other sea life resources in Minas Basin. We have images of poor little fishies being sucked into huge, rapidly-spinning turbines, coming out sushi at the far end.
No Such Thing
The problem occurs because of a misconception about what happens in a generating turbine. When we think of turbines and propellers, we think of metal objects churning up the water, as a boat’s propeller does. With generating turbines, we should think more of water wheels.
The key element in these machines is that the water is pushing the turbine. Thus the blades of the turbine are resisting the water and travelling slightly slower. In fact, instead of sucking marine life into the blades, this causes back pressure right in front of the turbine, and water tends to bend away and slide around it.
Experience has shown that fish avoid these turbines easily. In fact, they find back-eddies downstream of the turbine casings and sit there to take a rest where the current is slower.
But the emotional appeal of huge sharp blades slicing at high speed through little fishies is hard to counter.
According to Les Smith, Nova Scotia Power Interpreter at the plant, these objections have all been thoroughly dealt with. Nine years ago a consortium of industry, government, and environmental groups had a meeting where they set the policy for Fundy tidal power usage. It boils down to three simple regulations:
1. Whatever installation is placed on the sea bottom, it must be completely removable. No pilings, stakes, wood, concrete, etc.
2. The first installation must consist of a single unit.
3. Any subsequent installations must increase by small increments, with sufficient testing of their effect on environmental conditions before another increase is allowed.
So, according to Mr. Smith, the protesters have missed the last nine years. The fishermen protest that there is not enough data to say what effect this installation will have. The builders protest that until you put one unit in place, it is impossible to get any data.
It would seem that this Catch-22 is solvable if the three regulations are followed. One unit can be placed in the tidal flow, and data can be taken. If there is deleterious result, the unit must be removable, with nothing left behind. When more data is available, responsible decisions can be made. Nobody argues that more data is needed. A test turbine set down a few years ago lasted 36 hours before the tide wrenched the blades off the turbine. And of course, those who have observed government and industry in action are leery of such simple solutions. In the experience of many, the practicalities so often get pushed aside when elements of politics and profit weasel their way into the equation.
Progress Should Not Be a Four-Letter Word
However, as with the pipeline and hydro dam debates farther west, it comes down to the fact that we cannot simply stop all use of power. We need it to heat our homes and run our factories. The solution is to use it in the most responsible way.
Chicken Little Strikes Again
Public opinion has ignored global warming completely until it is almost too late. Now it has swung in the opposite direction, and wants use of fossil fuels stopped immediately. Somewhere in between is an unhappy medium where we are making progress in the right direction without completely destroying our means to live. This is not an easy time to be a politician.
I recall panics in the media about global famine when the world population was only half what it is now. So far, we still seem to be here. I can only hope that science and the efforts of intelligent, socially responsible people can continue to transform the tidal wave of disaster that threatens to engulf us into energy we can use to survive. The fact that there are only three tidal plants in the world at the moment demonstrates how far we have to go, and the potential power we could harvest.
Modern life is like Lewis Carroll’s Red Queen’s Race. We cannot stay where we are. If we stop trying, we will fall back. We must continue to strive to get ahead, just to stay even.