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Tidal energy is a potential renewable energy option for offshore and coastal countries. However, the first obstacle is to overcome cost issue and seawater erosion issue. Recently, Technical University of Madrid (its Spanish name: Universidad Politécnica de Madrid, UPM) developed a new generation tidal turbine generator and anchoring system. It can reduce a 30% share of total cost for a tidal power plant.
Typically, there are the following technical difficulties of new equipment: manufacture, installation and high maintenance fee. In order to overcome these issues, members of the Technological Research Group in Marine Renewable Energy (GITERM) at UPM developed new methods and procedures to evaluate the cost of a generator during its life span, and the team used feasibility analysis and simulation system to design simpler and more stable anchoring system, so that tidal power stations do not drift in the deep ocean.
Tidal energy is generated because the ocean water rises and falls between days and nights. Scientists believe that tidal energy is likely to be the next star of maritime renewable energy.
In particular, Scotland in UK installed the largest tidal power plant in the world in September 2017. Its highest record of power generation reached 700 MWh. The rest of European countries and Canada are preparing to install tidal power stations.
According to statistics, 80% of tidal energy takes place in 40 meter deep beneath the sea level. The reasons why second generation tidal energy system is necessary is because first generation tidal power system costs a lot in construction on the sea bed. The second generation tidal power system can save costs because of newly designed anchoring systems and cables that can fix the entire system to the seabed. In this way, the system will not be carried away by ocean current.
The new tidal device of UPM (a second generation tidal system) is called GESMEY. Its advantage is the much smaller size of turbine rotor while the first generation turbine rotor was as huge as that of onshore wind turbine rotor. In order to reduce cost of energy generation by about 30%, the second generation's tidal energy turbine actually uses multiple and smaller rotors.
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(Photo caption: The tidal turbine that is used in Scotland by Altantis, a tidal turbine manufacturer.)
Let's compare the first generation tidal turbine with that of the second generation. The shape of first generation tidal turbine is similar to that of a wind turbine. There are three blades and one pitch system in most of the first generation tidal energy system. Their yaw systems can change directions according to the movement of tides. The angle of turbine can turn 180 degrees. These tidal turbines look like electric fans on the sea bed. The size of first generation's tidal turbine is larger than the second. Its cost of installation on sea bed is higher than the second.
The second generation turbine is consisted of multiple rotors. The rotors are connected with submarine cables and anchoring systems on the sea bed. The size of second generation turbine is smaller and better fitting the deep sea. However, the official website of GITERM at UPM did not mention the power generation efficiency and data of construction cost.
Amable López, a researcher inn UPM, expressed that GESMEY system has earned a patent for the college. GESMEY is the world's first second generation tidal equipment that is tested and totally functional when immersed in the ocean. By using a cost analysis tool, the team evaluated multiple designs and lowered the cost. Therefore, this tidal energy system is competitive in terms of cost and technology.
José Andrés Somolinos, another researcher pointed out, tidal energy is more predictable than solar energy or wind power is. Thus, tidal power is easier to work with existing power grid. This feature will help tidal energy industry develop in the long term. The team of GITERM at UPM devoted to improve probability of commercialization for tidal energy system. Their new program and procedure designs are published on the journal of Renewable and Sustainable Energy Reviews.
(Photo credit: UPM)
