OTEC? That's the acronym for Ocean Thermal Energy Conversion, at it's a solution of how we can turn the ocean into a battery.
As the world becomes more and more dependent on electricity, the more the environment suffers from carbon gasses released by coal plants. Not to mention the higher risk of radiation poisoning if the nuclear powerplants have an accident.
But what's the solution? Solar power is excellent, but the sun doesn't always shine, and the wind doesn't always rotate turbines. There is, however, a solution. It's called Ocean Thermal Energy Conversion, also known as OTEC.
The basis of this technology is simple. Our oceans are giant batteries that absorb the heat from the sun and store it, all we have to do is harness it. There are various ways to do that, as some smart people have discovered.
It's called the Rankine Cycle and, while there are various ways to apply it, the fundamentals remain the same. It requires four parts; a boiler, a turbine, a condenser and a feed pump. The boiler heats the water, creating steam, which rotates the turbine, generating electricity. The condenser collects the steam and turns it back into water, and the feed pump returns the water to the boiler for the cycle to start again.
We've been doing this for hundreds of years, why don't we have these types of powerplants everywhere? Well, we do. It's the basis for almost every nuclear, gas and coal-fired powerplant in the world.
The question is, how can we heat up the water in the boiler without spewing harmful gasses into the air? Truthfully, you can't. But why does it have to be water? Other liquids have a far lower boiling point than water at 100 degrees Celcius. Ammonia, for example, has a boiling point closer to waters freezing point, and that's where OTEC steps in.
The surface temperature of the ocean is around 22 degrees Celcius. It drops to approximately two degrees Celcius near the ocean floor. So, if you pumped the warm surface water into the boiler, or evaporator as its also known, it would heat up the ammonia, turning it into steam to rotate the turbine. Pumping cold water from the sea bed into the condenser would convert the gas back into a liquid. Voila, no more pollution.
There are three variations to this cycle that do things slightly differently. The one described above is called the Anderson Cycle. It's a closed-loop system where the ammonia never leaves the system.
The second is an open-loop system called the Claude Cycle. This uses a flash evaporator to turn pressurised seawater into steam instead of ammonia liquid. This time, when the steam is converted in the condenser, it becomes desalinated water that can be extracted as drinking water. Thus, never going back into the loop.
The hybrid loop makes use of both cycles. The warm seawater goes through both the evaporator and the flash evaporator, thus heating up the ammonia liquid and converting into steam itself. The ammonia then remains in its loop, while the desalinated water is extracted.
To be clear, these are ridiculously simplified explanations, but they get the point across.
The big issue that we face, though, is location. These powerplants would need to be on a coastline in a narrow band of tropical waters, and many of the countries that fit this description are poor developing countries. The other important problem is that they require a lot of maintenance because of the nature of the ocean. Lastly, they're not very efficient at the moment.
But, there are a few companies already experimenting with this technology, and some of them are showing excellent results.
To find out more about OTEC, check out the video below by Joe Scott, who gives us an interesting breakdown of how all of this works. It's exciting, and you should watch it.