Q5 - Wave & Tidal Technologies Flashcards
Discuss the technology ‘oscillating water column’ system and explain how it works, the benefits and negatives and any real life examples
The Oscillating Water Column (OWC) is a type of wave energy conversion technology that harnesses the power of ocean waves to generate electricity. It operates based on the principle of using the rising and falling motion of water levels within a chamber to create air movement, which in turn drives a turbine to generate electricity. The key components of an OWC system include a chamber, a turbine, and a generator.
Here’s a step-by-step explanation of how the Oscillating Water Column system works:
Wave Action: As ocean waves approach the shore, they cause the water level inside the OWC chamber to rise and fall.
Air Movement: The rising and falling water levels create a corresponding movement of air within the chamber. When the water level rises, air is drawn into the chamber, and when the water level falls, the air is expelled.
Turbine Operation: The air movement is used to drive a turbine located at the top of the chamber. The turbine is connected to a generator, and as it spins, it generates electricity.
Electricity Generation: The generator converts the rotational energy from the turbine into electrical energy, which can then be transmitted to the grid for distribution.
Benefits of Oscillating Water Column (OWC) Systems:
Renewable Energy Source: OWC systems harness the power of ocean waves, providing a renewable and sustainable source of energy.
Low Environmental Impact: OWC systems typically have low environmental impact compared to some other forms of energy generation, as they don’t involve the burning of fossil fuels or the release of greenhouse gases.
Predictable Wave Patterns: Coastal areas often have predictable wave patterns, allowing for relatively stable energy production.
Adaptability: OWC systems can be adapted for various coastal environments and are suitable for both onshore and nearshore installations.
Negatives and Challenges:
Site Dependence: The efficiency of OWC systems is highly dependent on the specific characteristics of the coastal site, including wave height, frequency, and consistency.
Maintenance Challenges: Operating in a harsh marine environment can pose challenges for maintenance and durability of equipment.
High Initial Costs: The installation and infrastructure costs for OWC systems can be relatively high, potentially impacting the economic feasibility of these projects.
Limited Energy Density: The energy density of ocean waves is generally lower compared to some other renewable sources, which can limit the overall power output of OWC systems.
Real-Life Examples:
There have been several experimental and pilot projects around the world to test and demonstrate the feasibility of OWC technology. One notable example is the Limpet OWC on the Isle of Islay, Scotland. The Limpet (Land Installed Marine Powered Energy Transformer) facility was one of the world’s first grid-connected wave energy devices, and it operated successfully for several years.
Discuss the technology ‘pelamis’ and explain how it works, the benefits and negatives and any real life examples
Pelamis is a type of wave energy converter that takes its name from the Greek word for “snake” due to its serpentine shape. It is a semi-submersible device designed to convert the energy of ocean waves into electricity. The Pelamis Wave Energy Converter consists of a series of cylindrical sections linked by articulated joints. Each section contains hydraulic rams, and as the device moves with the motion of the waves, the hydraulic rams are actuated, pressurizing fluid that drives hydraulic motors, which, in turn, generate electricity.
Here’s a breakdown of how the Pelamis technology works:
Wave Motion: As ocean waves pass through the device, it causes the sections of the Pelamis to bend and flex along the joints.
Articulated Joints: The articulated joints between the cylindrical sections allow flexibility in response to wave motion. This flexibility allows the device to capture the energy of the waves along its length.
Hydraulic Rams: Each cylindrical section contains hydraulic rams that are actuated by the bending motion. As the sections flex, the hydraulic rams pressurize fluid.
Hydraulic Motors: The pressurized fluid is then directed to hydraulic motors, which convert the hydraulic energy into mechanical energy.
Electricity Generation: The mechanical energy generated by the hydraulic motors is used to drive electrical generators, producing electricity.
Benefits of Pelamis Technology:
Renewable Energy Source: Pelamis harnesses the power of ocean waves, providing a renewable and sustainable source of energy.
Predictable Wave Patterns: Coastal areas often have predictable wave patterns, allowing for relatively stable energy production.
Modular Design: The Pelamis device is modular, and multiple units can be connected to form larger wave farms, providing scalability.
Low Environmental Impact: Pelamis technology typically has low environmental impact compared to some other forms of energy generation, as it doesn’t involve the burning of fossil fuels or the release of greenhouse gases.
Negatives and Challenges:
Complex Engineering: The articulated joints and hydraulic systems of Pelamis devices involve complex engineering, which can contribute to higher manufacturing and maintenance costs.
Site-Specific Challenges: The efficiency of Pelamis systems is highly dependent on the specific characteristics of the coastal site, including wave height, frequency, and consistency.
Maintenance Challenges: Operating in a harsh marine environment can pose challenges for the maintenance and durability of equipment, especially given the complex mechanical systems involved.
High Initial Costs: The installation and infrastructure costs for Pelamis systems can be relatively high, potentially impacting the economic feasibility of these projects.
Real-Life Examples:
Pelamis Wave Power, the company behind the technology, developed and tested several prototypes in real-world conditions. One of the notable installations was the Agucadoura Wave Park off the coast of Portugal. It consisted of three Pelamis wave energy converters and was one of the world’s first wave farms connected to the grid.
Discuss the technology ‘wave dragon’ and explain how it works, the benefits and negatives and any real life examples
Wave Dragon is a wave energy converter technology designed to harness the energy from ocean waves and convert it into electricity. It is a floating platform that utilizes both the kinetic and potential energy of waves for power generation. The Wave Dragon system was developed by the Danish company Wave Dragon A/S.
How Wave Dragon Works:
Floating Platform: The Wave Dragon device consists of a large floating platform placed in the path of oncoming waves. The platform is typically anchored in shallow waters.
Oscillating Water Column: The platform has a ramp that allows waves to flow up and down. As waves approach the platform, they enter an oscillating water column (OWC) structure located at the rear of the platform.
Air Turbines: The oscillating motion of the water in the OWC causes air movement within the chamber. This oscillating air flow drives turbines, converting the mechanical energy of the moving air into electricity.
Power Generation: The electricity generated by the turbines is then transmitted to the grid or stored for later use.
Benefits of Wave Dragon:
Efficient Energy Capture: Wave Dragon is designed to efficiently capture energy from both the vertical movement of the waves and the horizontal flow of water on the ramp.
Modularity: The technology can be deployed as a single unit or in an array of interconnected units, allowing for scalability and adaptability to different locations.
Low Environmental Impact: Wave Dragon generally has a low environmental impact compared to some other forms of energy generation, as it doesn’t involve the burning of fossil fuels or the release of greenhouse gases.
Stability: The design of Wave Dragon provides stability in various wave conditions, making it suitable for a range of offshore environments.
Negatives and Challenges:
High Initial Costs: The construction and deployment of offshore energy systems, including Wave Dragon, can be expensive.
Maintenance Challenges: Operating in a harsh marine environment poses challenges for the maintenance and durability of equipment. Regular inspections and maintenance are crucial to ensure optimal performance.
Site-Specific Considerations: The efficiency of Wave Dragon may depend on specific site characteristics, including wave height, frequency, and water depth.
Real-Life Examples:
One notable example is the prototype installation off the coast of Nissum Bredning in Denmark. This project involved a full-scale demonstration unit that was grid-connected, providing valuable data for further development and optimization.
What is wave power and how can it be converted to useful power
Calculate how much wave power is available in the following example
Wave power refers to the energy derived from the motion of ocean waves. It is a form of renewable energy that harnesses the kinetic and potential energy of waves to generate electricity. The movement of water particles in response to wind creates oscillating waves, and capturing this energy can be done using various technologies. The goal is to convert the mechanical energy of the waves into electrical energy that can be used for various applications.
Discuss the technology ‘tidal barrage’ and explain how it works, the different types, flood, ebb and two-generation and there performance. State the benefits and negatives and any real life examples
A tidal barrage is a type of tidal energy conversion system that harnesses the energy from the rise and fall of tides to generate electricity. It typically involves the construction of a dam or barrage across the mouth of an estuary or tidal basin. As the tide comes in and goes out, the potential energy created by the tidal range is used to generate electricity through various mechanisms.
How Tidal Barrage Works:
Barrage Construction: A barrage is constructed across the entrance of an estuary or tidal basin, creating a barrier that controls the flow of water.
Sluice Gates: Sluice gates or turbines are installed in the barrage. These gates can be opened or closed to control the flow of water.
Tidal Cycle: As the tide rises, water is allowed to flow into the estuary through the sluice gates. During the ebb tide, the gates are closed, trapping water inside the estuary.
Hydroelectric Generation: When the gates are opened, the stored tidal water is released, flowing through turbines that generate electricity. This process can be repeated during each tidal cycle.
Types of Tidal Barrages:
Flood Generation: Flood generation involves capturing energy during the incoming tide as water enters the estuary. The gates are opened to allow the rising tide to fill the estuary, and then closed to trap the water. Subsequently, the gates are reopened to let the water flow through turbines for electricity generation.
Ebb Generation: Ebb generation captures energy during the outgoing tide. The gates are closed during high tide to trap water, and then opened during the ebb tide, allowing water to flow through turbines.
Two-Generation: Two-generation systems aim to capture energy during both the flood and ebb tides. This involves installing turbines on both sides of the barrage to generate electricity during both tidal cycles.
Benefits of Tidal Barrages:
Predictable Energy Generation: Tides are predictable and follow a regular cycle, providing a reliable source of energy.
Low Carbon Emissions: Tidal barrages produce electricity without the direct emission of greenhouse gases, making them a relatively clean energy source.
Long Lifespan: Tidal barrages can have a long operational life, contributing to long-term energy generation.
Flood Control: Tidal barrages can help mitigate the risk of flooding in estuarine areas by controlling the flow of tidal waters.
Negatives and Challenges:
Environmental Impact: The construction of tidal barrages can impact local ecosystems, affecting fish migration, sediment transport, and water quality.
High Initial Costs: Building tidal barrages can be expensive, and the economic feasibility of such projects may be a challenge.
Limited Sites: Suitable sites for tidal barrages are limited to estuaries with significant tidal ranges, restricting the geographic feasibility of these projects.
Discuss the technology ‘tidal stream turbine’ and explain how it works, the different types, flood, ebb and two-generation and there performance. State the benefits and negatives and any real life examples
Tidal stream turbines, also known as underwater or marine turbines, are a form of tidal energy technology that captures the kinetic energy from the flow of tides and currents to generate electricity. These turbines operate underwater and are similar in concept to wind turbines but are designed to capture the energy from moving water.
How Tidal Stream Turbines Work:
Underwater Installation: Tidal stream turbines are installed on the seabed or anchored to floating structures in locations with strong tidal currents.
Rotor Blades: The turbines have rotor blades that are designed to capture the kinetic energy of moving water. As water flows over the rotor blades, it causes them to rotate.
Power Generation: The rotational movement of the blades drives a generator, converting the mechanical energy of the rotating blades into electrical energy.
Tidal Cycle: Tidal stream turbines can operate during both the flood and ebb tide as tidal currents change direction, making them more versatile than some other tidal energy technologies.
Types of Tidal Stream Turbines:
Flood Generation: Turbines designed for flood generation are optimized to capture energy during the incoming tide when water flows into an area.
Ebb Generation: Turbines designed for ebb generation capture energy during the outgoing tide when water flows out of an area.
Two-Generation: Some tidal stream turbines are designed for two-generation operation, capturing energy during both tidal cycles as the direction of tidal currents changes.
Performance, Benefits, and Negatives:
Benefits:
Predictable Energy Source: Tidal currents are predictable and follow regular patterns, providing a reliable and predictable energy source.
Low Environmental Impact: Tidal stream turbines generally have a lower environmental impact compared to tidal barrages, as they don’t involve large-scale changes to estuarine ecosystems.
Constant Power Generation: Unlike some intermittent renewable sources like solar and wind, tidal currents are relatively constant, providing a continuous source of energy.
Negatives and Challenges:
High Installation and Maintenance Costs: Deploying and maintaining turbines in harsh marine environments can be expensive.
Limited Suitable Sites: Effective deployment of tidal stream turbines is limited to areas with strong and predictable tidal currents, restricting the number of suitable sites.
Potential Impact on Marine Life: The presence of turbines and their rotating blades could pose a risk to marine life, and careful environmental assessments are required.
Real-Life Examples:
MeyGen Tidal Energy Project, Scotland: The MeyGen project is one of the world’s largest tidal stream projects located in the Pentland Firth, Scotland. It consists of multiple tidal stream turbines that generate electricity from the strong tidal currents in the region.
Calculate maximum energy from the following tidal barrage
E = pg AR^2/2
Rearrange to
E= 0.5 X p x g x A x R^2
A = Area
R =Tidal Range
p = Water Density
g = gravity acceleration
Example
A=30km change of unit x 10^6
R = 6m
p =1000
g =10
E= 0.5 x (30x10^6) x 1000 x 10 x 6^2
= 5.4 x 10^12 MJ
