Tidal Power in the United States of America
Proposals for tidal power in the United States of America have been made in several states including Maine, Oregon, New York, and Florida. Maine is the first state to have implemented a commercial scale project.
Cobscook Bay, Maine
The Bay of Fundy is a large saltwater bay between Nova Scotia, New Brunswick, and the Northeastern tip of Maine. The larger structure of the bay gives way to a number of smaller bays and inlets in both the United States and Canada. With tidal ranges between 6 meters (20 feet) and 15 meters (49 feet), the bay has long been of interest to groups interested in tidal power.
Cobscook and Passamaquoddy Bay both average around eighteen feet of tidal range throughout the year. The bays were first considered for possible electricity generation in the 1930s under President FDR and then again in the 1960s by President Kennedy. In both cases, the scales of the projects were prohibitive. Both settings are more amenable to tidal stream generation, though barrage-type projects have been proposed. The University of Maine has been instrumental in exploring the possibilities for tidal power.
Cobscook Bay is a complicated bay in Maine between the border of the United States and Canada. It has long been a source of tidal power schemes, with early settlers to the United States using tidal mills to grind grain. As of July 2012, Cobscook Bay became home to the first grid-tied tidal power generator in the United States.
The generator is known as TidGen and is made by Ocean Renewable Power Company. The system is ultimately a tidal stream generator that consists of a proprietary turbine design that produces 180 killowatts of energy at peak output and looks much like the paddle wheel found on boats in the late nineteenth century. The turbine is designed to be low maintenance and to have limited impact on fish and other wildlife. Future plans call for a total of 5 megawatts of generating capacity.
The installation is being monitored for the following environmental impacts
- Fish migration
- Atlantic Salmon
- Atlantic Sturgeon
- Marine life interaction
- Leatherback sea turtle
- Loggerhead sea turtle
- Marine mammals
- Sei whale
- Fine whale
- North Atlantic Right whale
- Humpback whale
- Sea and shore birds
- Benthic and biofouling
Oregon, Hawaii, and Washington states are all investigating tidal power schemes. Oregon State University and the University of Washington have created the Northwest National Marine Renewable Energy Center (NNMREC) that seeks to understand tidal power from all aspects. Estimates suggest that the West Coast states (WA, OR, CA) could generate as much as 600 Twh of electricity per year while Hawaii could generate 130 Twh per year. Alaska itself could generate over 1,300 TWh of electricity per year.
The NNMREC is funded by the U.S. Department of Energy. Research projects are centered around the following key areas:
- Cost effectiveness of various sites and devices
- Device performance
- Generate guidelines for future monitoring
- Assist with regulatory guideline implementation
- Modeling of environmental effects from device operation
- Static effects such as water column disturbances
- Dynamic effects such as blade strike, entrainment, device wake, etc.
- Chemical effects
- Acoustic effects
- Electromagnetic effects such as fields associated with the generator or power cable
- Energy removal from tidal systems
- Cumulative effects
- Optimization of various devices
- Wake modeling
- Maximizing pack density
- Reliability and maintenance of devices (material sciences)
- Modeling of composite material and biofouling properties
- Structural analysis
- Composite aging
Florida, the East Coast, and the Gulf of Mexico
Estimates are that power generation from South Carolina through Florida could reach as much as 40 TWh/year and that the Gulf of Mexico could potentially generate 80 TWh/year. These estimates are much smaller than for the northern part of the East Coast (Maine through North Caroline), which has an estimated potential of over 200 TWh/year. These estimates include wave energy as well as tidal energy.