Ocean thermal energy conversion technology makes use of the difference in temperatures between the cool deep water and warm shallow waters or the seawater on the seas to drive heat engines and make advantageous work, mostly in the shape of electricity. The thing that makes ocean thermal energy conversion so useful is that it is always available and is derived from a renewable energy resource. Compared to other energy forms from the ocean, ocean thermal energy conversion has much more potential.
The amount of energy that can be produced from ocean thermal energy conversion is mindboggling. In fact, it is possible to generate as much as 88, 00 tWh/year of power with ocean thermal energy conversion. Best of all, this power could be generated without endangering the thermal structure of the oceans.
There are two types of systems that are available for ocean thermal energy conversion. The first is the closed-cycle system while the other one is called the open-cycle system. The former type makes use of refrigerants and other fluids, which have special characteristics like lower boiling points. Such a characteristic makes this kind of fluid more suitable for generating electricity. Typical example of the closed-cycle system is the Rankine cycle.
Open-cycle systems on the other hand make use of vapor from the seawater. The nice thing about using ocean thermal energy conversion is that its byproduct is cold water and this byproduct can be put to good use like for air conditioning as well as for refrigeration. Fresh-water that has been distilled from the sea is another byproduct of the open-cycle system.
The first ocean thermal energy conversion theory was developed in the latter part of the nineteenth century. It took another thirty odd years for the first demonstration of this system. At present, there is only one such operating plant and that one is located in Japan. In fact, Japan has made major contributions to ocean thermal energy conversion technologies. The country has built as well as successfully deployed ocean thermal energy conversion systems on a plant in an island called Nauru.
A third ocean thermal energy conversion system that is often deployed is the one called the hybrid system. Each ocean thermal energy conversion system makes use of cold seawater. However, for operational purposes this cold seawater must be brought up to the ocean surface and this can either be done by active pumping or by desalination.
The thing that makes ocean thermal energy conversion such a potent tool is the fact that it is capable of producing so much power that it could one day even lead to the total elimination of fossil fuel consumption. The problem is that this kind of system is very costly and hence we need to find an effective way of lowering costs because people are going to be driving electric cars everywhere soon.
Also, such a system also requires very long as well as big intake pipes that need to be sent down into the ocean to depths of a kilometre or more. This must be done in order to extract the cold seawater from the bottom of the ocean to its surface. There are land-based facilities that offer some advantages over those that are located in the oceans. The land-based facilities are also more cost-effective and are easy to maintain as compared to the deep-water facilities.