We have already heard of renewable energy systems who use kites planes to generate electricity through the wind. The Manta system is similar, but it has a peculiarity. Use a kite underwater that “flies” in tidal or river currents.
Manta was conceived by scientists from the SRI International research institute. The company recently received funding fromEnergy Agency (ARPA-E) for advanced research projects of the US Department of Energy.
How the Manta Underwater Kite Works
The heart of the system is the composite polymer-coated foam underwater kite. Its shape (guess what?) was inspired by the manta ray. It is attached to a cable anchored to the ocean or river bottom in areas that have strong currents. The cable base is equipped with both an electric motor and a generator.
At the beginning of each of its runs, the kite is positioned to capture the full force of the current, and is carried downstream da the current one. The reel spins quickly as it releases the cord (like a fishing rod). This movement spins the generator and produces electricity that can be stored in a battery or fed directly into the grid.
When the kite reaches the end of its string, it changes its angle to reduce resistance to the current: the spool motor winds it up, to then make it perform another downstream run. Although the winching process still requires some energy, its amount is much less than that generated by the system. According to a report, SRI aims for an average production of around 20 kilowatts per kite.
Economical, effective, sustainable
Compared to other tidal power systems that incorporate structures such as underwater turbines, Manta is claimed to be significantly cheaper and easier to install. The centerpiece of the system, the underwater kite, can simply be reeled in when there is a chance it might interfere with nearby human activities or wildlife. In any case, the designers say, the lightness of the kite would make it compact and risky even when in motion.
SRI said it now intends to build and operate a prototype to demonstrate the Manta technology, although they are still awaiting news of where it will be located and when it will be completed.
Source: SRI International
