Apr 12, 2008

Bagaduce River slowed by 15% if tidal turbines installed?

The Tidal Energy Device Evaluation Center (TEDEC) operated by a consortium that includes Maine Maritime Academy proposes to run a variety of experimental turbines and other kinds of water energy devices in the Bagaduce river.

The idea is to take advantage of the powerful flow of water through the Bagaduce Narrows; turbines and other devices will collect energy from the water moving into and then out of the tidal Bagaduce River.

Another capital idea for electricity sans burnt hydrocarbons.

Don't let's forget to look at the bigger picture. Not much bigger; the Bagaduce is a small pocket watershed. Perched near the top of Penobscot Bay with Castine at its mouth, the Bagaduce River stretches a dozen miles in a shape best described as a lower case "h" with Castine at the bottom of the main stem of the "h", vast mudflats at the top of the stem, and oysterfarms inteh curving part of the h.

Consider this. A report written by the power consortium notes that the Bagaduce Narrows power operation could result in a "15% Energy Withdrawal" from the river at the narrows.

If that means that the Bagaduce River could face a 15% drop in current velocity, then there are implications for the filterfeeders upriver; both the natural and the aquacultured ones. Would the amount of planktonic prey delivered to these shellfishes' fixed locations per tide cycle be reduced by 15%? That would be problematic for the river's oyster farmers, whose productivity and hence income would decline by $15%. Not to mention the natural mussels, clams and other filterfeeding invertebrates residing in the river, all of whom rely on spot-on delivery of food at just the right time and in the right amount.

Reduced current=less prey species=less shellfish. Yes or no? Who can say? Nothing in the MMA materials available so far appears to examine this vital question. Just keep in mind that the energy taken from the river is energy no longer available to things living in the river.

No free lunch. We are simply be taking the oysters, clams and mussels' lunches!

Let's get this answered before going too much further.

2 comments:

jacob said...

I have a home on the coast of Northern Bay. In my opinion, the reduction of flow by a couple tidal turbines, would probably be unmeasurably small. even tho the Bagaduce rive is small, the tides traveling through the narrows produces immense amounts of energy. I wouldn't be surprised if it was closer to .15%

Ron Huber said...

Will check with MMA and the agencies. Tidal energy, or, more properly, "lunar energy", is more reliable than any other renewable energy source. The outcomes of the R&D activity on the Bagaduce should, one hopes, launch tidal generation as appropriate technology within tidal waters of Maine and beyond.

But, like all extractive industries, the environment of the location where the tidal energy withdrawal takes place is/will be changed.

Whether the changes are benign or injurious, it is the duty of the state to require those changes be identified and quantified, and examined for their impacts, onsite and off short term and over time. Only then are informed decisions possible.