Future Perfect: Harvesting ocean currents with underwater turbines
WhatÃ¢Â€Â™s happening right now?
High amount of energy can be produced using ocean current turbines. It is to be noted that the movement of the ocean currents is slower than the speed of wind, but waterÃ¢Â€Â™s density is 800 times more than air, which means that the force exerted by a slow moving current is as much as a fast and steady wind. The basic design of ocean current turbines is similar to the wind turbines but the only difference is that turbines work well under water.
The installation and maintenance of these turbines are a costly affair because they are placed inside sea and faces underwater hazards. One key thing which is kept in mind before designing the ocean current turbines is that they should not harm the environment of the ocean.
1. Underwater turbine harvests tidal energy
Two large underwater rotors generate power using the strong tidal currents. Siemens has bought 10 percent stake in Marine Current Turbines, an operator company, in 2010. It is expected that by 2014 a larger plant will get completed in Scotland. This plant with a total output of 8 MW will provide electricity to around 8,000 households.
2. Turning the tide to energy
The researchers at NASA have developed technology to power robotic vehicles under ocean and they are of the view that the energy of ocean can be used to generate electrical energy on a massive scale. According to the researchers, the clean and renewable energy produced from the ocean current can meet the global demand for electricity. We are already using moving water to generate electricity and one of the best examples is the hydroelectric plants, which are used to generate electricity using the large hydrostatic pressure difference that is developed between the water trapped behind the dam and the turbines that are used to generate power. The amount of power which we can generate using hydroelectric plants is limited, so there is a need to harness strong ocean currents to generate power and meet the energy requirements of people across the world.
3. Underwater Kite turbine generates electricity from ocean currents
In this project, underwater kites are used to harvest the ocean currentsÃ¢Â€Â™ force. In this project, a movable string is used to attach a kite to a turbine and the movement of this string is based on the direction of the tide. Swedish firm Minesto has developed the technology to harness this massive power source. By using kites with the turbines, Minesto managed to captures 1,000 times more energy than what is produced by the tides. The best thing about this technology is that it can be used to generate electricity even with slow moving currents. A nonprofit firm named The Carbon Trust donated $560,000 to the company to develop this technologyÃ¢Â€Â™s functional prototype. Minesto is hopeful that this technology can be used to power around 200,000 homes by 2020.
It is expected that the environment would not face any major trouble from single units harvesting ocean current turbines, but it is likely that large array of these turbines could have negative affect environment. Research found that an array of 240 units generating around 10,000 MW could reduce the Gulf StreamÃ¢Â€Â™s speed by around one percent, which is less than the diurnal and annual natural fluctuations of the current. Some other major issues related to environment are withdrawal of hydrokinetic energy, marine life interactions, the emissions from atmosphere and ocean, visual appearances, and conflicts fishing, shipping and other uses of sea. Some recent studies have found that even large arrays do not pose much threat to the environment. Before moving ahead with the decision to install underwater turbines, it is important to examine three major issues: the impact of installation on the seafloor and support facilities at the shoreline, the impact of the operation and decommissioning.
Besides impact of the installation of the underwater turbine on environment, there are some other concerns as well. These turbines do not cause much effect impact on humans and coastal societies because they are installed very deep under the water. If the turbine is located near the shore limits, it does not allow fishermen to operate there. After the selection of an adequate location, it is important to select the right current tidal energy mechanism, which should be compatible with the specific characteristics of the site. Presently, there are three types of energy harvesting turbine: Kite Structure, Vertical Axis and Horizontal Axis.