OTEC

Capturing energy using temperature gradients across water depths.

Ocean thermal energy conversion (OTEC) technology converts solar energy stored in the layers of the tropical and subtropical oceans. Thermal heat engines use the temperature difference between the sun-warmed surface water and cold water in the deep ocean. The temperature difference between surface waters and deeper water can reach over 25 oC in summer months, although usually this temperature difference exists only over water with depths of 1,000 m or greater. Many different OTEC archetypes have been investigated, some on floating offshore platforms and some built onshore with pipelines to transport the water to and from the ocean. Each system uses one or a combination of thermodynamic processes to turn the temperature difference into mechanical energy.

  • Closed-cycle: A working fluid with a low-boiling point, such as ammonia or propane, is circulated. Warm, surface seawater is pumped through a heat exchanger where the working fluid is vaporized and driven through a turbine, which then generates electricity. Cold, deep seawater is then pumped through a second heat exchanger where the working fluid vapor condenses back into a liquid and is recycled through the system.
  • Open-cycle: Warm, surface seawater is placed in a low-pressure container that causes the water to boil, turning a turbine as the steam expands. The steam is then exposed to cold, deep seawater and condenses into freshwater.
  • Hybrid-cycle: Warm, surface seawater enters a vacuum chamber where it is flash-evaporated into steam. The steam is used to vaporize a working fluid with a low-boiling point, which then turns a turbine to generate electricity. Hybrid configurations also produce freshwater, which can have other uses such as agriculture and potable drinking water.

The primary environmental concerns associated with OTEC technologies typically encompass changes in water quality. A major environmental concern arises as cool, nutrient rich water is withdrawn from the deep ocean and discharged higher in the water column. The effects of this cooler water and transport of nutrients on ecosystem processes could vary but may affect nearby habitats through temperature changes or increased biological growth. Screens will cover the intake tubes, but there is still a chance that marine organisms could be fatally entrapped. In order to maintain the efficiency of the heat exchangers, the warm water will need to be treated with chlorine, which will cause changes to water quality.

Photo Credit: Okinawa Prefecture Industrial Policy Division

Affiliated Marine and Wind Energy Environmental Documents

Total results: 101
Title Author Date Content Type Technology Stressor Receptor
Environmental Impacts of Renewable Energy Mazhar, N., Zia, S. Book Chapter Marine Energy, OTEC, Wave, Wind Energy
A framework to evaluate the environmental impact of OCEAN energy devices Mendoza, E., Lithgow, D., Flores, P. Journal Article Marine Energy, Ocean Current, OTEC, Tidal, Wave, Wind Energy, Fixed Offshore Wind Human Dimensions
Study of the currentology of Moroccan facades and assessment of the marine energy potential for the fight against the impact of climate changes Hariss, S., Saifaoui, D., Hilmi, K. Conference Paper Marine Energy, Ocean Current, OTEC, Wind Energy, Fixed Offshore Wind Human Dimensions, Climate Change
Decision framework for ocean thermal energy plant site selection from a sustainability perspective: The case of China Zhang, J., Xu, C., Song, Z. Journal Article OTEC, Marine Energy Legal & Policy, Human Dimensions
On the Marine Energy Resources of Mexico Hernández-Fontes, J., Felix, A., Mendoza, E. Journal Article Marine Energy, Ocean Current, OTEC, Salinity Gradient, Wave Ecosystem Processes, Physical Environment
Offshore Ocean Thermal Energy Conversion in Layang-Layang Island, Sabah-Malaysia Fahmie, M., Koto, J., Tasri, A. Journal Article Marine Energy, OTEC Human Dimensions
Analysis of the environmental issues concerning the deployment of an OTEC power plant in Martinique Devault, D., Péné-Annette, A. Journal Article OTEC, Marine Energy
Legal Considerations on OTEC Deployment in Malaysia Rani, M., Yusof, M., Mahdzir, A. Report Marine Energy, OTEC Human Dimensions, Legal & Policy
Potential of 100 kW of Ocean Thermal Energy Conversion in Karangkelong, Sulawesi Utara, Indonesia Negara, R., Koto, J. Journal Article Marine Energy, OTEC Human Dimensions
Integration of wave energy and other marine renewable energy sources with the needs of coastal societies Manasseh, R., Sannasiraj, S., McInnes, K. Journal Article Wind Energy, Wave, Tidal, OTEC, Fixed Offshore Wind, Ocean Current, Marine Energy Social & Economic Data, Human Dimensions
Potential of ocean thermal energy conversion in Indonesia Koto, J. Journal Article Marine Energy, OTEC Human Dimensions
Progress in Renewable Energies Offshore Soares, C. Book Marine Energy, OTEC, Tidal, Wave, Wind Energy, Fixed Offshore Wind
Study on Electrification of Remote and Isolated Tropical Islands Using OTEC Hassan, M., Habib, W., Rupam, T. Conference Paper Marine Energy, OTEC Physical Environment, Human Dimensions, Social & Economic Data
Reviews of Power Supply and Environmental Energy Conversions for Artificial Upwelling Zhang, D., Fan, W., Yang, J. Journal Article Wave, OTEC, Marine Energy
Environmental Impact Assessment for an OTEC Plant in Martinique Island Auvray, C., Ledoux, S., Diaz, B. Journal Article Marine Energy, OTEC Human Dimensions, Environmental Impact Assessment
An Economic and Environmental Assessment of Transporting Bulk Energy from a Grazing Ocean Thermal Energy Conversion Facility Gilmore, E., Blohm, A., Sinsabaugh, S. Journal Article Marine Energy, OTEC Physical Environment, Human Dimensions
Observing Ocean Changes at the Nation's First SWAC System Comfort, C., Ostrander, C., McManus, M. Presentation Marine Energy, OTEC Ecosystem Processes
Potential Environmental Consequences of Enhanced Ocean Upwelling Karl, D., Böttjer, D., Clemente, T. Presentation Marine Energy, OTEC Ecosystem Processes
Effect of OTEC Thermal Effluent on the Kosrae Coastal Waters of the Micronesia Kim, J., Mun, J., Kim, H. Presentation Marine Energy, OTEC Changes in Flow
The Potential Impacts of OTEC Intakes on Aquatic Organisms at an OTEC Site under Development on Kauai, HI Oney, S., Hogan, T., Steinbeck, J. Report Marine Energy, OTEC Entanglement Fish
Effects of Ocean Thermal Energy Conversion Systems on Near and Far Field Seawater Properties - A Case Study for Hawaii Jia, Y., Nihous, G., Richards, K. Journal Article OTEC, Marine Energy Changes in Flow Water Quality, Physical Environment
Modeling the Physical and Biochemical Influence of Ocean Thermal Energy Conversion Plant Discharges into their Adjacent Waters Grandelli, P., Rocheleau, G., Hamrick, J. Report Marine Energy, OTEC
Modeling the Physical and Biochemical Influence of Ocean Thermal Energy Conversion Plant Grandelli, P., Rocheleau, G., Hamrick, J. Report OTEC, Marine Energy Habitat Change Water Quality, Physical Environment, Ecosystem Processes
Revisiting ocean thermal energy conversion Fujita, R., Markham, A., Diaz, J. Journal Article Marine Energy, OTEC Changes in Flow, Entanglement Invertebrates, Physical Environment, Water Quality
Assessment of Ocean Thermal Energy Conversion Muralidharan, S. Thesis OTEC, Marine Energy
Environmental assessment for ocean thermal energy conversion in Hawaii: Available data and a protocol for baseline monitoring Comfort, C., Vega, L. Conference Paper Marine Energy, OTEC
Electricity Generation by the Ocean Thermal Energy Etemadi, A., Emdadi, A., AsefAfshar, O. Journal Article OTEC, Marine Energy Habitat Change Physical Environment
Physical and Biological Modeling of a 100 Megawatt Ocean Thermal Energy Conversion Discharge Plume Rocheleau, G., Grandelli, P. Conference Paper Marine Energy, OTEC Habitat Change Ecosystem Processes, Physical Environment
Research and Developments on Ocean Thermal Energy Conversion Wang, C., Yee, A., Krock, H. Journal Article OTEC, Marine Energy
Status of Hawaii's ocean energy projects and permitting regime Gill, A., Black, C. Conference Paper Marine Energy, OTEC, Wave Human Dimensions, Environmental Impact Assessment, Legal & Policy
Ocean Thermal Energy Conversion (OTEC) Power Plant and it's By Products Yield for Small Islands in Indonesia Sea Water Siahaya, Y., Salam, L. Conference Paper Marine Energy, OTEC Human Dimensions
Bringing OTEC Environmental Assessments of the 1980s Up To 21st Century Oceanographic Standards Sansone, F., Comfort, C., Weng, K. Conference Paper Marine Energy, OTEC
Ocean Thermal Energy Conversion: Assessing Potential Physical, Chemical and Biological Impacts and Risks Cunningham, J., Magdol, Z., Kinner, N. Report Marine Energy, OTEC
An Overview Of Ocean Renewable Energy Technologies Bedard, R., Jacobson, P., Previsic, M. Magazine Article Wind Energy, Wave, Tidal, OTEC, Fixed Offshore Wind, Marine Energy
Potential Environmental Effects of Ocean Thermal Energy Conversion Sound and Sea Technologies Presentation Marine Energy, OTEC
Potential OTEC Impacts in the Hawaiian Marine Environment Parke, M. Presentation OTEC, Marine Energy
Ocean Thermal Energy Conversion (OTEC) Environmental Impacts NOAA Office of Ocean & Coastal Resource Management Report Marine Energy, OTEC
Ammonia Energy Storage, Transmission and Usage Development for Offshore Wind and Applicability to OTEC Hart, G., Holbrook, J. Conference Paper Marine Energy, OTEC, Wind Energy, Fixed Offshore Wind, Floating Offshore Wind Physical Environment
Worldwide Synthesis and Analysis of Existing Information Regarding Environmental Effects of Alternative Energy Uses on the Outer Continental Shelf Michel, J., Dunagan, H., Boring, C. Report Wind Energy, Wave, OTEC, Fixed Offshore Wind, Ocean Current, Marine Energy Habitat Change
Overview of Environmental Effects: OTEC vs Other Power Generation Methods Martí, J. Presentation OTEC, Marine Energy
Displaying 41 - 80 of 101 results