1.1 Overview of Ocean Energy Types and Potential
3 min read•august 7, 2024
Ocean energy harnesses the power of tides, waves, currents, and temperature differences to generate electricity. These renewable sources offer vast potential, with a global theoretical capacity exceeding four times the world's current electricity consumption.
Tidal, wave, and capture kinetic power from water movement. uses temperature differences, while taps into the mixing of fresh and saltwater. These sustainable alternatives can help combat climate change.
Types of Ocean Energy
Tidal Energy and Wave Energy
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- harnesses the power of tidal currents caused by the gravitational pull of the moon and sun
- use a dam-like structure to capture water during high tide and release it through turbines during low tide (Bay of Fundy, Canada)
- utilize to capture energy from tidal currents without the need for a barrage (Pentland Firth, Scotland)
- captures the kinetic energy of ocean waves and converts it into electricity
- devices use the rise and fall of waves to compress air and drive a turbine (Mutriku Wave Energy Plant, Spain)
- are buoys that move with the waves, driving a generator to produce electricity (PowerBuoy, Ocean Power Technologies)
Ocean Thermal Energy Conversion (OTEC) and Salinity Gradient Energy
- Ocean thermal energy conversion (OTEC) utilizes the temperature difference between warm surface water and cold deep water to generate electricity
- systems use a working fluid (ammonia) that is vaporized by warm surface water and condensed by cold deep water to drive a turbine
- systems use warm surface water as the working fluid, which is flash-evaporated in a vacuum chamber to drive a turbine (Makai Ocean Engineering, Hawaii)
- Salinity gradient energy, also known as osmotic power, harnesses the energy released when freshwater and saltwater mix
- (PRO) uses a semi-permeable membrane to separate freshwater and saltwater, creating a pressure difference that drives a turbine (Statkraft, Norway)
Marine Current Energy
- Marine current energy captures the kinetic energy of ocean currents, such as the Gulf Stream, to generate electricity
- Underwater turbines, similar to wind turbines, are placed in areas with strong and consistent ocean currents to produce power (Verdant Power, New York)
- Marine current energy has the advantage of being more predictable and consistent compared to other ocean energy sources
Ocean Energy Potential
Global Ocean Energy Potential
- Ocean energy has the potential to provide a significant portion of the world's electricity demand
- The global theoretical potential of ocean energy is estimated to be around 93,100 TWh/year, which is more than four times the world's current electricity consumption
- Tidal energy alone has a global potential of approximately 1,200 TWh/year, equivalent to the annual electricity consumption of the European Union
- Ocean energy resources are widely distributed across the globe, with high potential in regions such as Europe, North America, and Asia
- The United Kingdom has one of the highest tidal energy potentials in the world, with an estimated 10 GW of installable capacity
- The Pacific Northwest region of the United States has significant wave energy potential, with an average wave power density of 40 kW/m
Renewable and Sustainable Ocean Resources
- Ocean energy is a renewable resource, as it relies on the continuous motion of tides, waves, and currents, which are driven by the gravitational pull of the moon and sun, as well as wind and temperature differences
- Unlike fossil fuels, ocean energy sources do not deplete over time and do not contribute to greenhouse gas emissions
- Ocean energy can play a crucial role in mitigating climate change and reducing dependence on finite and polluting energy sources
- Ocean energy is a sustainable alternative to conventional energy sources, as it has minimal environmental impact and can coexist with other marine activities
- Tidal and wave energy devices have a small footprint and can be designed to minimize interference with marine life and shipping routes
- OTEC and salinity gradient energy systems can be integrated with other ocean-based industries, such as desalination and aquaculture, to create sustainable multi-purpose platforms
Key Terms to Review (32)
Capacity Factor: The capacity factor is a measure of how effectively an energy generation system produces electricity compared to its maximum potential output over a specific period. It reflects the actual energy output relative to the maximum possible output if the system operated at full capacity continuously, which is essential for understanding the efficiency and reliability of energy systems, especially in the context of renewable sources like ocean energy.
Closed-Cycle OTEC: Closed-cycle OTEC (Ocean Thermal Energy Conversion) is a renewable energy technology that generates electricity by utilizing the temperature difference between warmer surface seawater and colder deep seawater. This system operates in a closed loop, where a working fluid is vaporized using the warm surface water, and then the vapor is condensed back into liquid using the cold deep water, driving a turbine connected to a generator. This method effectively harnesses ocean thermal gradients to produce sustainable energy while minimizing environmental impact.
Continental shelf: The continental shelf is a submerged landmass that extends from the coastline of a continent to the deep ocean floor, typically characterized by shallow waters. This area plays a crucial role in marine ecosystems and is also rich in natural resources, including oil, gas, and minerals, making it significant for ocean energy potential and global distribution.
Cost of energy: The cost of energy refers to the total expenses associated with producing and delivering energy to consumers, often expressed in terms of price per kilowatt-hour (kWh). This term encompasses capital costs, operational and maintenance costs, fuel costs, and any incentives or subsidies that can affect pricing. Understanding the cost of energy is essential as it influences the feasibility and attractiveness of different energy sources, particularly in assessing the potential of ocean energy technologies.
Energy Conversion Efficiency: Energy conversion efficiency refers to the ratio of useful energy output from a system to the total energy input, expressed as a percentage. It is a critical measure that helps determine how effectively a technology converts energy sources, such as ocean waves or tides, into usable power, and impacts the overall viability of energy systems.
Energy Density: Energy density refers to the amount of energy stored in a given system or region of space per unit volume or mass. This concept is crucial when evaluating different energy sources, as it directly impacts their efficiency, feasibility, and potential for power generation from various natural phenomena such as tides and waves.
Fluid Dynamics: Fluid dynamics is the branch of physics that studies the behavior of fluids (liquids and gases) in motion. This field is crucial for understanding how energy can be harnessed from ocean movements, such as waves and tides, as it provides insights into the forces and flow patterns that can impact energy conversion systems, efficiencies, and designs. Fluid dynamics principles help engineers predict how water interacts with structures and devices that capture ocean energy, enabling them to optimize performance and reliability.
Global ocean energy potential: Global ocean energy potential refers to the vast capacity of the world's oceans to generate renewable energy through various technologies, including tidal, wave, thermal, and salinity gradients. This potential is significant because it represents a sustainable energy resource that can help reduce dependence on fossil fuels and mitigate climate change effects. Understanding this potential involves exploring the different types of ocean energy and their respective contributions to the overall energy landscape.
Habitat disruption: Habitat disruption refers to the alteration or destruction of natural environments that affects the organisms living within those ecosystems. This can occur due to human activities, such as energy production, and has significant implications for biodiversity and ecological balance.
Hydrodynamics: Hydrodynamics is the study of fluids in motion, particularly focusing on the forces and interactions that occur when water flows. This field is crucial for understanding how ocean energy systems harness wave and tidal movements, which are influenced by factors like flow velocity, pressure distribution, and fluid behavior around structures.
Incentives for renewable energy: Incentives for renewable energy are policies and financial mechanisms designed to encourage the development and use of clean, sustainable energy sources. These incentives can take various forms, such as tax credits, grants, feed-in tariffs, and subsidies, aimed at reducing the cost burden on renewable energy projects. By making these technologies more financially viable, incentives promote investment and innovation in the renewable sector, which is critical for addressing environmental concerns and achieving energy sustainability.
Levelized Cost of Electricity: Levelized cost of electricity (LCOE) is a measure used to compare the cost-effectiveness of different energy generation methods by calculating the per-unit cost of producing electricity over the lifetime of a project. It incorporates initial capital costs, operations and maintenance expenses, fuel costs, and the total amount of electricity generated, allowing for a clear comparison between renewable energy sources like tidal and wave energy and traditional fossil fuels.
Marine current energy: Marine current energy refers to the kinetic energy generated from the movement of ocean currents, which can be harnessed to produce electricity. This renewable energy source is derived from the natural flow of water, driven primarily by tidal forces and wind patterns, making it a reliable and predictable form of energy generation. As one of the significant categories within ocean energy, marine current energy showcases the vast potential of harnessing ocean resources for sustainable power generation.
Marine Impact Assessment: Marine impact assessment is a systematic process used to evaluate the potential environmental effects of proposed marine projects, particularly in the context of ocean energy development. This evaluation aims to ensure that marine ecosystems are protected and that any negative impacts are minimized or mitigated. Such assessments are crucial in understanding how various ocean energy types and technologies, like wave energy converters and point absorber systems, interact with marine life and habitats.
Ocean energy policy: Ocean energy policy refers to the frameworks, regulations, and strategies that govern the development and utilization of ocean energy resources, including wave, tidal, thermal, and salinity gradients. This policy aims to promote sustainable energy generation while addressing environmental impacts, economic feasibility, and technological advancement in harnessing ocean energy sources. Effective ocean energy policy is crucial for balancing energy needs with ecological preservation and fostering innovation in marine technologies.
Ocean thermal energy conversion: Ocean thermal energy conversion (OTEC) is a process that utilizes the temperature difference between warmer surface seawater and colder deep seawater to generate renewable energy. This technology can harness significant energy potential, especially in tropical regions where the temperature gradient is most pronounced, contributing to the broader spectrum of ocean energy types and their potential applications.
Open-cycle OTEC: Open-cycle OTEC, or Ocean Thermal Energy Conversion, is a technology that harnesses the temperature difference between warm surface seawater and cold deep seawater to generate electricity. This method utilizes the warm water to vaporize a working fluid, typically ammonia, which drives a turbine connected to a generator, and then the cold deep seawater condenses the vapor back into liquid. The process not only generates power but can also provide additional benefits like freshwater production and cooling.
Oscillating Water Column: An oscillating water column (OWC) is a type of wave energy converter that uses the movement of water within a column to generate energy. As waves enter the column, they create changes in water levels, causing air above the water to be compressed and expanded, which can drive a turbine to produce electricity. This mechanism connects with various aspects of wave energy technology and site assessments for effective energy capture.
Permitting Process: The permitting process is a formal procedure that involves obtaining the necessary approvals and permits from regulatory agencies to construct and operate ocean energy projects. This process is crucial as it ensures compliance with environmental, safety, and zoning regulations, and helps to assess the potential impacts of these projects on marine ecosystems and coastal communities.
Point Absorbers: Point absorbers are a type of wave energy converter that harnesses energy from the up-and-down motion of ocean waves. These devices typically consist of a buoyant structure that moves with the waves, allowing it to capture kinetic and potential energy through its motion relative to a fixed base. This technology plays a crucial role in the broader context of ocean energy potential and various engineering applications.
Pressure-Retarded Osmosis: Pressure-retarded osmosis (PRO) is a process that harnesses the osmotic pressure difference between freshwater and seawater to generate energy. This method leverages the natural flow of water through a semipermeable membrane, where freshwater moves into a concentrated seawater solution, creating a pressure that can be converted into usable energy. PRO is considered a promising technology in the context of ocean energy due to its potential for sustainable power generation without significant environmental impacts.
Renewable Energy Potential: Renewable energy potential refers to the capacity of natural processes to generate energy from renewable sources, such as solar, wind, hydro, and ocean energies. This concept emphasizes the abundance of these resources and their ability to provide sustainable energy solutions while reducing reliance on fossil fuels. Understanding this potential is crucial for developing effective energy policies and technologies that harness ocean energy types.
Return on Investment: Return on Investment (ROI) is a financial metric used to evaluate the profitability or efficiency of an investment relative to its cost. In the context of renewable energy, particularly ocean energy, ROI plays a crucial role in assessing the viability of projects, comparing the potential financial returns from ocean energy systems against their installation and operational costs. This evaluation helps stakeholders make informed decisions about investments in technologies such as tidal and wave energy.
Salinity Gradient Energy: Salinity gradient energy is the energy generated from the difference in salt concentration between seawater and freshwater, which can be harnessed to produce electricity. This form of renewable energy exploits the chemical potential that exists at the interface of these two water types, leading to innovative energy generation methods. The potential for salinity gradient energy is significant, as it taps into an abundant resource available in many coastal regions worldwide, contributing to the broader landscape of ocean energy.
Sustainability: Sustainability refers to the ability to meet present needs without compromising the ability of future generations to meet their own needs. This concept encompasses environmental health, social equity, and economic viability, ensuring that energy systems are not only efficient but also responsible in their impact on the planet and society. It is crucial in the development of ocean energy systems, where considerations for ecosystem preservation and resource management play a vital role in harnessing energy from tides and waves effectively.
Tidal Barrages: Tidal barrages are large structures built across the entrance of estuaries or tidal rivers, designed to harness the energy generated by the rise and fall of tides. These systems work by trapping water during high tide and releasing it through turbines during low tide, converting kinetic energy into electrical energy. Tidal barrages play a significant role in the broader context of ocean energy technologies, which aim to provide renewable energy solutions while minimizing environmental impact.
Tidal Energy: Tidal energy is a form of renewable energy that harnesses the gravitational forces exerted by the moon and the sun on Earth's oceans to generate electricity. This energy is produced through the rise and fall of sea levels, creating tidal currents that can be captured using various technologies. Tidal energy is part of a broader category of ocean energy sources, which also includes wave energy, and is recognized for its potential to contribute significantly to global energy needs due to its predictability and reliability.
Tidal Stream Generators: Tidal stream generators are devices that convert the kinetic energy of moving water caused by tidal currents into electrical power. They harness the predictable flow of tides, making them a reliable renewable energy source, and their effectiveness is influenced by the geographic and hydrodynamic characteristics of specific locations.
Tidal Stream Sites: Tidal stream sites are specific locations in marine environments where the flow of tidal currents is strong enough to generate significant amounts of kinetic energy. These sites are ideal for harnessing tidal energy through underwater turbines that convert the kinetic energy of moving water into electricity. The potential for energy generation at tidal stream sites depends on various factors, including water depth, current speed, and geographical features that influence tidal flows.
Underwater turbines: Underwater turbines are devices designed to harness the kinetic energy of moving water, typically in oceans or rivers, to generate electricity. These turbines operate similarly to wind turbines, but instead of capturing air movement, they capture the flow of water currents. This technology is an essential part of the ocean energy landscape and plays a significant role in tapping into the vast renewable energy potential available in marine environments.
Wave Energy: Wave energy is the energy harnessed from the movement and oscillation of water waves, primarily generated by wind blowing across the ocean's surface. This renewable energy source has significant potential for sustainable power generation, as it can be captured and converted into electricity using various technologies. The characteristics of wave energy depend on factors such as wave height, frequency, and period, making it an area of interest in discussions about renewable energy development.
Wave hotspots: Wave hotspots are specific areas in the ocean where wave energy is significantly more intense due to favorable geographic and climatic conditions. These regions are characterized by consistent, strong wave patterns that make them ideal for harnessing wave energy, which can contribute substantially to the overall potential of ocean energy generation.