The bridge sensor network, information communication system and aesthetic lighting are powered by a locally available renewable energy resource, tidal energy. Aesthetic lighting and social media is used to communicate relevant information from the bridge and environmental sensors, such as weather, tides and traffic to the local community. The information collected with these sensors is shared with researchers, bridge designers and the bridge owner, but also, where appropriate, with K-12 classrooms and the public. The use of tidal power, globally, has been quite limited because there are only a few sites in the world that see sufficiently large variations in tides to produce enough power, as shown in the table below.This bridge is instrumented with sensors that capture structural performance, traffic patterns, environmental conditions, the behavior of innovative bridge design elements and enable and promote community engagement. Because this tidal activity is predictable (each coast sees at least one tidal cycle per day – high tide and low tide – and some areas actually see two tidal cycles on a daily basis), tidal energy projects have the advantage of being able to provide a fairly predictable source of electricity. The systems depend on regular tidal activity to generate power. Tidal energy projects typically work by forcing water through a turbine or a “tidal fence” that looks like a set of subway turnstiles. The periodic wave activity at this depth is typically used to power a pump that feeds into a turbine, generating electricity. Offshore wave energy systems are typically placed deeper in the ocean, though not too deep – perhaps a few hundred feet below the ocean’s surface. The motion powers a hydraulic pump and a generator. A flap is hinged over the opening, and the action of the waves causes the flap to swing back and forth. Pendular Devices: Pendular wave-power devices consist of a rectangular box that is open to the sea at one end.The waves spill over the walls of the channel into the reservoir, and the stored water is then fed through a turbine. The narrowing of the channel causes the waves to increase in height as they move toward the cliff face. Tapchans: Tapchans, or tapered channel systems, consist of a tapered channel that feeds into a reservoir constructed on cliffs above sea level.As the wave retreats, the air is drawn back through the turbine as a result of the reduced air pressure on the ocean side of the turbine. This alternately compresses and depressurizes the air column. As waves enter the air column, they cause the water column to rise and fall. It encloses a column of air above a column of water. Oscillating Water Columns: Oscillating water columns consist of a partially submerged concrete or steel structure that has an opening to the sea below the waterline.The US Department of Energy has a nice description of different types of surface wave projects as follows: Surface wave energy technologies capture the kinetic energy in breaking waves – these provide periodic impulses that spin a turbine. Wave energy projects extract energy from waves on the surface of the water, or from wave motion a bit deeper (a few 10s of meters) in the ocean. Both refer to the extraction of kinetic energy from the ocean to generate electricity (again, by spinning a turbine just as hydroelectric dams or wind farms do), but the locations of each and the mechanisms that they use for generating power are slightly different. In terms of power generation technologies, wave and tidal power have both similarities and differences. Tides, related to the gravitational pull of the Moon and Sun on the oceans, are like very long-wavelength waves that can produce very strong currents in some coastal areas due to the geometry of the shoreline. Waves, driven by the winds, make the water oscillate in roughly circular orbits extending to a depth of one half of the wavelength of the wave (distance between peaks). Water in the oceans is constantly in motion due to waves and tides, and energy can be harvested from these kinds of motions.
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