Ocean Renewable Power Company (ORPC) is installing the largest tidal power plant to date in U.S. waters. The Maine-based energy company is using the movement of tides to generate renewable power for the U.S. Coast Guard station in Eastport, Maine. The bay's five-knot tides provide a predictable, clean source of energy.
While tidal water moves more slowly than wind, it provides more force. Tide velocities peak four times a day, and one of ORPC’s innovations is developing the systems to harness that power as the turbine spins at different rates. The power plant will use advanced cross-flow turbines, a permanent magnet generator and a power electric system that transforms the generator’s energy output to grid-suitable electricity.
The barge-based plant uses the power from two turbines to charge large battery packs, which are ferried daily by skiff to the Coast Guard station in Eastport. The battery packs provide roughly 20 kilowatt-hours of power daily, about half of the energy needs of the 41-foot search and rescue boat docked there.
This plant is a small power plant, as it would take 25 such turbines to equal the rated capacity of one average wind turbine.
This “demonstration” project cost $4 million, including more than a million dollars of federal and state support. ORPC is using the data it is gathering to fine-tune a larger installation in Cobscook Bay, planned for 2011. That system, according to the company, should generate enough electricity to power 50 or 60 homes.