2007 CBC Tidewalker Associates Presentation
View Normand LaBerge's Presentation as .pdf
Normand Laberge of Tidewalker Associates is a professional engineer. He started working on the Half Moon Cove tidal power project in 1977 when he was employed by the Passamaquoddy Tribe. His project proposes to dam off Half Moon Cove at the point where the Old Toll Bridge Road used to cross from Perry to Eastport. The idea is that water will build up behind the dam during the incoming tide and be held in the impoundment. The water would then be released through a turbine in order to generate electricity.
Inside the impoundment the tidal range would be reduced to about a 9-12 foot tide. Areas that are intertidal now would become subtidal, losing about 1,000 acres of clamflats. The basin area is 1.2 square miles at high tide and .46 square miles at low tide.
Laberge explained that the power house and the filling gates would be built in the middle of the dam. The power house could consist of up to three turbines producing 4.5 kilowatts each. The dam itself would be 1,200 feet across. The dam would extend 25 feet above highest high tide. He believes the site of the dam is especially well situated because of the canyon in the middle of the channel, which is a natural fit for the power house. The dam would be a “rock fill” dam and would require rocks from local quarries. The schematics of the power house include two bulb turbines, flap gates for filling and emptying, a roadway on the dam’s surface, and high pool operation.
The electricity generated by a tidal power project needs to cost less than $.05/kilowatt hour in order to be competitive, Laberge said. He believes that using a dam makes the production of energy predictable; you would know exactly when energy was going to be produced and when it was not. You might even be able to get a credit for times of peak generation.
Laberge noted that the strong tidal current at the proposed site of the dam might also be used for modular in-current devices such as those suggested by ORPC and the Tribe. He also entertained the possibility of opening the existing causeway between Pleasant Point and Carlow’s Island and installing a powerhouse there. Another possibility raised was building a road across the top of the dam at the Old Toll Bridge, which might also afford rail access to Eastport.
He believes that the project is compatible with the Quoddy Bay LNG proposal. Benefits to the community include: economic development through construction jobs and dam operations jobs, possible aquaculture development within the containment area, and the possibility that the dam might become a tourist attraction.