physics

Marine energy

Marine energy is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Marine energy rather than just read about it. In short: Marine energy, also known as ocean energy, ocean power, or marine and hydrokinetic energy, refers to energy harnessed from waves, tides, salinity gradients, and temperature differences in the ocean. The movement of water in the world's oceans stores vast amounts of kinetic energy, which can be converted into electricity to power homes, transportation, and industries.

Key takeaways

Marine energy belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Marine energy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Marine energy from memory before moving on to harder problems.

Reference excerpt

Marine energy, also known as ocean energy, ocean power, or marine and hydrokinetic energy, refers to energy harnessed from waves, tides, salinity gradients, and temperature differences in the ocean. The movement of water in the world's oceans stores vast amounts of kinetic energy, which can be converted into electricity to power homes, transportation, and industries.

Marine energy includes wave power, which is derived from surface waves, and tidal power, which is obtained from the kinetic energy of moving water. Offshore wind power, however, is not considered marine energy because it is generated from wind, even if the wind turbines are located over water.Ocean energy has the potential of providing a substantial amount of new renewable energy around the world. While marine energy is a sustainable alternative to fossil fuels, its development can impact marine ecosystems, wildlife, and the physical environment. Potential effects include habitat disruption, noise pollution, and electromagnetic fields from subsea cables, which may require mitigation strategies such as fish-friendly turbine designs and environmental impact assessments. Government policies, economic incentives, and regulatory frameworks contribute significantly to advancing marine energy, with countries like the UK, Canada, and South Korea leading in tidal and wave energy projects.

Global potential The global potential for marine energy is significant, with estimates suggesting that 20,000 to 80,000 terawatt-hours per year (TWh/y) of electricity could be generated from ocean temperature differences, salinity gradients, tides, currents, waves, and swells.

Indonesia, as an archipelagic country that is three quarters ocean, has 49 GW recognized potential ocean energy and has 727 GW theoretical potential ocean energy.

Forms of ocean energy

The oceans are a vast, largely untapped source of energy, including surface waves, fluid flow, salinity gradients, and thermal differences. Marine and Hydrokinetic (MHK) or marine energy development in U.S. and international waters includes projects using the following devices:

Wave power converters in open coastal areas with significant waves; Tidal turbines placed in coastal and estuarine areas; In-stream turbines in fast-moving rivers; Ocean current turbines in areas of strong marine currents; Ocean thermal energy converters in deep tropical waters.

Marine current power

Strong ocean currents are driven by temperature, wind, salinity, bathymetry, and the rotation of the Earth. The Sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with no changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines. Ocean currents are instrumental in determining the climate in many regions around the world. While little is known about the effects of removing ocean current energy, the impacts of removing current energy on the farfield environment may be a significant environmental concern. The typical turbine issues with blade strike, entanglement of marine organisms, and acoustic effects still exists; however, these may be magnified due to the presence of more diverse populations of marine organisms using ocean currents for migration purposes. Locations can be further offshore and therefore require longer power cables that could affect the marine environment with electromagnetic output.

Osmotic power

At the mouth of rivers where fresh water mixes with salt water, energy associated with the salinity gradient can be harnessed using pressure-retarded reverse osmosis process and associated conversion technologies. Another system is based on using freshwater upwelling through a turbine immersed in seawater, and one involving electrochemical reactions is also in development. Significant research took place from 1975 to 1985 and gave various results regarding the economy of PRO and RED plants. Small-scale investigations into salinity power production take place in other countries like Japan, Israel, and the United States. In Europe the research is concentrated in Norway and the Netherlands, in both places small pilots are tested. Salinity gradient energy is the energy available from the difference in salt concentration between freshwater with saltwater. This energy source is not easy to understand, as it is not directly occurring in nature in the form of heat, waterfalls, wind, waves, or radiation.

Ocean thermal energy

Water typically varies in temperature from the surface warmed by direct sunlight to greater depths where sunlight cannot penetrate. This differential is greatest in tropical waters, making this technology most applicable in water locations. A fluid is often vaporized to drive a turbine that may generate electricity or produce desalinized water. Systems may be either open-cycle, closed-cycle, or hybrid.

Tidal power

The energy from moving masses of water – a popular form of hydroelectric power generation. Tidal power generation comprises three main forms, namely tidal stream power, tidal barrage power, and dynamic tidal power.

Wave power

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Marine energy

Start with the simplest possible case. Write down what Marine energy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Marine energy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Marine energy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Marine energy

In research: Marine energy appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Marine energy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Marine energy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Marine energy, Oceanographical terminology, Water power, so understanding it makes those chapters shorter.
In everyday life: Look for Marine energy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Marine energy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Marine energy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Marine energy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Marine energy in simple terms?

Why does Marine energy matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Marine energy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Marine energy.