Whether it’s wind, sun, or tidal waves, the Earth provides an array of energy sources to support industries, homes, and individuals. Researchers and environmentalists have also pushed for clean energy, in the face of the growing threat of climate change.
These groups have also tried to find innovative ways to harness the energy of the Earth so that more communities can participate in the clean energy movement. Although they have started to gain momentum, oil, coal and natural gas still make up a large part of the world’s energy supply.
However, promising innovations have emerged in recent years. An increasingly sought-after renewable resource is called Ocean Thermal Energy Conversion (OTEC), in which changes in sea temperature are used to generate electricity. Using this heat could prove to be a great achievement, given that the ocean covers two-thirds of the Earth’s surface.
How can the heat of the oceans be used as a source of renewable energy?
The conversion of thermal energy from the oceans produces renewable energy thanks to the differences in water temperature. At the surface of the ocean, temperatures are much warmer than those on the seabed. It gets much colder the deeper you go because sunlight cannot reach the bottom. These temperature differences are most noticeable in summer, when the sun is present during most hours of the day.
Sunlight is free, which is why solar power is so attractive to those interested in renewables. The rays that heat the Earth and provide energy for solar power also heat the oceans. It renews itself every day, and because much of the Earth’s surface is covered with water, the OTEC process can generate billions of watts of electricity.
The process of turning these temperature distinctions into usable energy has required years of extensive research. Put simply, OTEC uses a series of pipes that extract cooler water from the depths of the ocean. Warm water on the ocean surface helps heat cold water, which then vaporizes a fluid and, as a result, spins a turbine to generate electricity.
This new source of renewable energy would likely perform better in warmer climates near the equator. These zones produce the temperatures necessary for the operation of the OTEC systems. Although it is an excellent energy resource, rising ocean temperatures are still a cause for concern. This can harm aquatic life and lead to declining populations around the world.
Technology needed for renewable energy from ocean heat
Three types of renewable energy systems for ocean heat are under development and research. An OTEC closed cycle is perhaps the most common and the most studied, consisting of a condenser, an evaporator, pumps, a turbine and a generator. There are also open systems and hybrid systems.
The OTEC process exploits temperature differences, also known as thermal gradients, between surface waters and deep ocean waters. Throughout the day and during the hottest times of the year, the sun heats the surface water. It will likely warm several degrees warmer than deeper waters in tropical climates.
This change in temperature can generate electricity and remove salinity. OTEC systems require a temperature difference of at least 77 F. This difference powers a turbine that produces electricity for various applications.
The systems work by pumping warmer surface water through an evaporator containing a low boiling point working fluid, such as ammonia. Once the fluid is vaporized, it is used to drive a turbine and generator. From there, the vaporized fluid becomes liquid again through a condenser, cooled by cold, deep ocean water rising from the depths. OTEC systems that use seawater can use condensation to produce salt-free water.
OTEC systems must place the technology approximately 1 kilometer below the surface of the water. The cold water intake pipe is in the deepest area and the piping where the hot water enters is above sea level. Pumps are needed to move hot water through the system, and a heat exchanger is needed to evaporate the fluid. Condensers condense the vapor produced in the system and a buoy keeps the entire system afloat.
While this concept of using ocean heat as a renewable energy source is incredibly appealing to those interested in conservation and terrestrial energy, the problem lies in the location of the system and the location. where energy 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 the earth, so a new consideration is to host the system on land.
Benefits of ocean heat as a renewable energy source
The more renewable energy sources become available and affordable, the more likely people are to become less dependent on fossil fuels to heat their homes and run their appliances. Energy is essential for almost all human activity. If the world is to avoid an energy crisis, people must start relying on renewable energy.
Fortunately, all three types of OTEC can provide energy to large populations. The oceans cover a large part of the Earth’s surface, and if the developers used even a tiny 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 the offshore versions.
OTEC can also provide constant and stable power due to the daily renewed appearance of the sun, and there is no need for energy storage, which would save money and space on Earth. This global resource is sufficient to produce at least four times the electricity needs of humanity.
In addition, a single offshore plant can prevent the burning of millions of barrels of oil every year, and this would significantly reduce carbon dioxide emissions. As more research and development is devoted to this renewable energy source, the Earth has a chance to become cleaner and more sustainable.
Towards sustainable energy sources
Using the ocean as a source of energy is a great way to reduce harmful emissions from non-renewable sources. The sea is a huge resource and OTEC systems can provide endless power generation to people around the world. It has the potential to be a great source of clean energy as long as it continues to gain the support of researchers, developers and environmentalists.