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Ocean Energy

  • Last Updated : 02 Jun, 2021

A source of energy is one that can consistently provide enough usable energy for a long period of time. Energy can be categorized as Renewable sources of energy and Non-Renewable sources of energy or classified as Conventional sources of energy and Non- conventional sources of energy. Energy is the strength of a body to do work. Without resources, no action can take place. As a result, energy is needed in all aspects of life.

Classification of Sources of Energy:

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  1. Conventional Sources of Energy: Fossil fuels (coal, oil, and natural gas), hydro energy (energy from water flowing through rivers), biomass energy, and wind energy are all examples of energy sources that are widely used and meet a significant portion of our energy needs.
  2. Non-conventional Sources of Energy are those that are not as widely used as traditional ones and only fulfill a small portion of our energy needs. This group includes solar energy, ocean energy (tidal energy, wave energy, ocean thermal energy, OTE), geothermal energy, and nuclear energy.

Let’s discuss one of the non-conventional sources of energy i.e. energy from the sea as:



Energy from the Sea

Due to the enormous volume of water and the motion of waves, the seas, oceans, and other bodies of water are a source of kinetic and potential energy. The oceans cover about 71% of the Earth’s surface. Because of its high specific heat, the enormous amount of water present in them not only acted as a large collector of solar heat energy but also as a large store of it. As a result, ocean water can be used, as a renewable resource of energy.

Tides are periodic rises and fall in water level that occur twice every lunar day. On new and full moon days, there are high tides; otherwise, there are low tides. The moon’s and sun’s gravitational forces on ocean water cause these tides to occur. The difference in tide levels generates ocean thermal energy.

A tidal dam is built to capture its energy, and the ocean water is confined by a barrier. This water is then permitted to fall into a water turbine, transforming the kinetic energy of the flowing water into mechanical energy, which is ultimately converted into electrical energy. The difference in tidal levels should be around 3 m. Tides do not form all the time. 

Sea energy has a significant energy potential, but commercializing it efficiently is tough. The sea can provide the following forms of energies:

Types of Energy from the Sea

  1. Ocean Thermal Energy: Ocean Thermal Energy is the energy available as a result of the temperature differential between the ocean’s deeper depths and its surface. During the day, the water at the sea’s surface is hot, while the water at a lower level is cold. The difference in temperature between water levels can be used to produce electricity. Ocean thermal energy can be captured if the temperature difference is greater than 20 °C, then that location can be used to generate ocean thermal energy. A volatile liquid, such as ammonia, is boiled using the heat from the surface of the water. The volatile liquid’s steam is used to power the engine, which generates electricity. The cycle is repeated by using colder water from the soil below to condense ammonia vapor, which is then channeled back to the surface.
  2. Tidal Energy: The rising of ocean water due to the moon’s attraction is known as high tide, and the falling of ocean water is known as low tide. Tidal Energy is a large amount of energy generated by the tremendous movement of water caused by high and low tides. Through building a tidal barrage or dam, this tidal energy can be harnessed. The movement of water can be used to produce energy as it returns to the ocean. It can only be found near the shore of the sea.
  3. Wave Energy: Waves may also be used to generate electricity. Wave energy refers to the energy produced from high-speed sea waves. In reality, the kinetic energy associated with these high-speed sea waves can be used to power dynamos that convert kinetic energy to electrical energy. To generate wave energy, a variety of devices are being developed and tested. A hollow tower, for example, is constructed near the seashore. The air is forced upwards when water gushes through the tube due to the wave. A turbine is powered by the kinetic energy of the air in the tube. When the wave breaks, air from above enters the tube, which is often used to power the turbine.
  4. Geothermal Energy: ‘Geo’ stands for Earth, and ‘thermal’ stands for hot. The thermal energy produced and deposited within the Earth’s crust is known as geothermal energy. Owing to the continuous mechanism of nuclear fusion, the Earth’s core maintains the same temperature as the Sun, which is nearly constant. Because of the high temperature and pressure, some rocks melt, causing the mantle to rise (as they become lighter with the heat). The molten rocks that form in the Earth’s crust are forced upward and become stuck in an area known as a “hot spot.” Steam is generated when underground water comes into contact with the hot spot. This hot water-formed area sometimes seeks outlets at the surface. Hot springs are formed when hot water gushes from one of these outlets.

Applications of Energy from the Sea

  1. Electricity generation: Within a two-mile radius of the geothermal reserve, geothermal power plants are usually constructed. The steam from these reserves is used to either directly rotate the turbines of an electrical generator or to heat water and then generate steam for the operation.
  2. Farming: In colder climates, geothermal energy is used to heat greenhouses or water used for irrigation.
  3. Industry: Geothermal energy is used in the industry for food dehydration, milk pasteurization, gold mining, and other processes.
  4. Heating: Geothermal energy is used to heat buildings by district heating systems, in which hot water from springs is piped directly into the structures.

Advantages of Energy from the Sea

  • Geothermal energy is a renewable resource that is both free and plentiful. This resource is inexhaustible and infinite for an estimated 4 billion years due to the steady flow of heat from the Earth.
  • Unlike fossil fuels, geothermal energy is non-polluting and environmentally safe since no harmful gases are released when it is used. In addition, there are no residues or by-products.
  • Geothermal power plants are highly sophisticated and require extensive study prior to construction. This creates a large number of jobs for skilled and unskilled workers at any level of production and management.
  • Geothermal energy can be used directly in cold countries for melting ice on highways, heating homes in the winter, greenhouses, public baths, and other applications. The cost of maintenance and repair is insignificant, despite the high initial cost of installation.

Disadvantages of Energy from the Sea

  • Geothermal energy, unlike fossil fuels, is difficult to transport. After the tapped energy has been harnessed, it can only be used effectively in the immediate vicinity. There’s also a risk that poisonous gases will be emitted into the environment as a result of the transmission.
  • Building geothermal power plants to extract steam from deep beneath the Earth necessitates a significant investment in both material and human capital.
  • Extensive research is needed before establishing a plant, as the sites can run out of steam over time due to a drop in temperature as a result of the excessive or erratic supply of inlet water.
  • Geothermal energy is only available in a few areas, some of which are extremely difficult to reach, such as high-rise mountains and rocky terrains, making the process economically un-available in many instances.
  • Since geothermal sites are located deep underground, the drilling process can result in the release of highly toxic gases into the environment around these sites, which can be fatal to the workers involved.

Sample Problems

Problem 1: What is energy?

Solution:

The capacity to do work or the overall power generated from our natural resources is referred to as energy. Energy comes in a variety of ways and can be transformed from one to another. Energy in usable form is dissipated as a less usable form into the environment.



Problem 2: Give two advantages and two disadvantages of tidal energy.

Solution:

Advantages of Tidal Energy:

  • It is an inexhaustible and environment friendly source of energy.
  • It has low operation and maintenance costs.

Disadvantages of Tidal Energy:

  • There are very few sites around the world which are suitable for building tidal barrages.
  • The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.

Problem 3: What are the limitations of wave energy?

Solution:

The Limitations of Wave Energy are:

  • It has a negative influence on marine life forms.
  • The sea wave intensity is variable.

Problem 4: What are the advantages of Ocean Thermal Energy?

Solution:

The advantages of Ocean Thermal Energy are:

  • It can be used continuously 24 hours a day throughout the year due to sun and ocean currents.
  • It is a renewable source of energy
  • Its use does not cause any pollution.
  • Mixing of deep and shallow seawater brings up nutrients from the sea floor. The deep water is rich in nitrates and this can also be used in agriculture.

Problem 5: Define a good source of energy?

Solution:

A good source of energy is the one that would do a large amount of work per unit mass (or per unit volume), is cheap and easily available, is easy to store and transport, is safe to handle and use, and does not cause environmental pollution.




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