Utilizing Ocean Heat as a Renewable Energy Source

Whether it’s the wind, sun or tidal waves, the Earth provides a spectrum of power sources to sustain industries, homes and individuals. Researchers and environmentalists have been pushing for clean energy, as well, contending with the rising threat of climate change.


These groups have also been trying to find innovative ways to capture the Earth’s energy so more communities can participate in the clean energy movement. Though they’ve started to gain momentum, petroleum, coal and natural gas still account for much of the world’s energy supply.


There have been promising innovations in recent years, however. An increasingly researched renewable resource is called ocean thermal energy conversion (OTEC), in which the sea’s temperature variations are used to produce power. Utilizing this heat could prove to be a great achievement, given that the ocean covers two-thirds of the Earth’s surface.


How Can Ocean Heat Be Used as a Renewable Energy Source?

Ocean thermal energy conversion produces renewable power through the water’s temperature distinctions. On the surface of the ocean, the temperatures are much warmer compared to the seafloor. It gets considerably colder the deeper you go because the sunlight cannot reach the bottom. These temperature differences are most noticeable in the summer when the sun is present for a majority of the hours of the day.


Sunlight is free, which is why solar power is so appealing to those interested in renewable energy. The rays that warm the Earth and provide energy for solar power also heat the oceans. It renews each day, and since so much of the Earth’s surface is covered in water, the OTEC process can generate billions of watts worth of electricity.


The process to turn these temperature distinctions into workable energy has taken years of extensive research. To put it simply, OTEC uses a series of pipes that extract the cooler water in the depths of the ocean. The warm water on the ocean’s surface helps heat the cool water, which then vaporizes a fluid, and as a result, turns a turbine to produce electricity.


This new renewable energy source would likely work best in warmer climates near the equator. These areas produce the temperatures needed for the OTEC systems to function. Although this is an excellent resource for energy, there’s still a concern about rising ocean temperatures. This can harm aquatic life and cause a decline in populations around the world.


Technology Needed for Ocean Heat Renewable Energy

Three types of ocean heat renewable energy systems are being developed and researched. An OTEC closed-cycle is perhaps the most common and well-researched, consisting of a condenser, evaporator, pumps, turbine and generator. There are also open systems and hybrid systems.


The process of OTEC harnesses the temperature differences, also called thermal gradients, between surface and deep ocean waters. Throughout the day, and in warmer times of the year, the sun heats the surface water. It will likely heat up to be many degrees warmer than deeper water in tropical climates.


This temperature variance can produce electricity and remove salinity. The OTEC systems need a temperature difference of at least 77 F. This difference powers a turbine that produces electricity for various applications.


Systems work by pumping the warmer surface water through an evaporator containing a working fluid with a low boiling point, such as ammonia. Once the fluid vaporizes, it is used to drive a turbine and generator. From there, the vaporized fluid turns back into a liquid through a condenser, cooled by the cold, deep ocean water that pumps up from the depths. The OTEC systems that use seawater can use condensation to make water without salt.


OTEC systems need to place technology about 1 kilometer below the surface of the water. The cold water intake pipe is in the deepest area, and the piping where warm water enters is above sea level. The pumps are needed to move warm water into the system, and a heat exchanger is required to evaporate the fluid. Condensers condense the steam produced in the system, and a buoy keeps the entire system afloat.


Although this concept of utilizing ocean heat as a renewable energy source is incredibly appealing to those interested in conservation and earth-powered energy, the issue lies within the location of the system and the location where power is needed. The necessary thermal gradient only works in seas and works most efficiently in tropical climates. However, the energy it produces is needed for land, so a new consideration is housing the system onshore.


Benefits of Ocean Heat as a Renewable Energy Source

The more renewable energy sources that become available and affordable, the more likely people will become less reliant on fossil fuels to heat their homes and run appliances. Energy is essential for almost all human activities. If the world wants to avoid an energy crisis, people need to begin relying on renewable energy.


Fortunately, the three types of OTEC can provide energy for large populations. Oceans cover so much of the Earth’s surface, and if developers used even a minute region of the oceans for this purpose, it could generate enough electricity to power the globe. The same systems exist on land, but moving them to the sea would be cheaper, easier and more efficient than offshore versions.


OTEC can also provide constant and steady power due to the renewed daily appearance of the sun, and there’s no need for energy storage, which would save money and space on land. This global resource is enough to produce at least four times humanity’s electrical needs.


Furthermore, just one offshore plant can prevent millions of barrels of oil from being burned each year, and it would significantly reduce carbon dioxide emissions. As more research and development goes into this renewable energy source, the Earth has a chance of becoming cleaner and more sustainable.


Moving Toward Sustainable Energy Sources

Using the ocean for power is a great way to reduce harmful emissions from nonrenewable sources. The sea is an immense resource, and OTEC systems can provide unending electrical generation for populations worldwide. It has the potential to be an excellent clean energy source as long as it continues to gain support from researchers, developers and environmentalists.


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