Global Campaigns: Tidal Range and OTEC

Name
Professor
Course
14 November 2018
Tidal Range and OTEC
Recent global campaigns encourage people to shift from the use of fossil fuels to renewable energy to deal climate change. Fossil fuels as a source of energy have devastating consequences. Scientists associate global warming to the emission of gases, both of which lead to more severe problems such as changes in vegetation and habitat, extinction of wild animals, melting of polar ice caps, rising of sea levels and depletion of natural resources. Tidal range and Ocean Thermal Energy Conversion (OTEC) are among sources of renewable energy. Others include solar power, wind energy, and hydropower.
Tidal range power plants are dams built in areas where the tidal range is enough to produce electricity economically. The plants operate by creating a human-made tidal phase difference; holding water and then releasing through a turbine. Tidal range power plants consist of embankments, turbines, openings, and locks and can be of three types: barrage (coastally attached), lagoon (entirely offshore) or coastally-attached lagoons (Mackinnon et al., 309).
Ocean Thermal Energy Conversion (OTEC) utilizes the sun’s energy. The sun heats the ocean surface up to 25°C, while the deepwater remains cold. The natural thermal gradient of the sea is used in OTEC to produce electricity by creating stem from the heat stored in warm water and re-condensing the steam using cold deep water. (Etemadi et al., 937). There are two types of OTEC. In a closed- cycle, working fluid with a low boiling point such as ammonia is heated by warm sea water and the vapor turns a turbine which generates electricity. Cold water is pumped to condense the vapor. In an open-cycle, warm seawater is pumped, and flash evaporated in a vacuum chamber, and the steam drives a turbine. Cold water is then pumped to condense the steam into water (Etemadi et al., 937). Hybrid plants combine the benefits of the two. OTEC plants are constructed onshore or offshore.
The wetted surface area of the impounded water and the difference in water level between the upstream and downstream sides determines the energy output of tidal range plants. Turbines and the sluice gates regulation also determine energy extraction, they can be designed o for either one-way or flood-only, or bidirecti...