The Italian increasing interest in the exploitation of wave and tidal technology to produce clean and renewable energy can be recognized either in some Government initiatives (e.g. the higher incentive for such sources) or in the research activities.
Mainly universities and companies specialized in research and innovative designs are involved in R&D in this field, thanks to which Italy is at forefront in research, development and demonstration at a prototypal level. The offshore wind farm production is also supported through a special support mechanism.
Strategy and National Targets
The new Ministerial Decree on renewable energy sources (DM 6 July 2012) reviews the support schemes (till now based on feed-in tariffs and green certificates) for grid connected renewable energy power plants (non PV). The new Decree concerns plants put into operation since 1 January 2013 (with capacity ≥ 1 kW).
The new Decree identifies four different ways of access to incentives: direct access, bid auctions (Dutch auctions), registries for new power plants, for fully reconstructed power plants, for reactivated, empowered and hybrids power plants and registries for rebuilding intervention. The new Decree defines the criteria to access to the Registries and the Dutch auctions and establishes specific limits for the annual capacity eligible to incentives. These limits are set up differently for each kind of renewable energy sources and for all the different ways of access to incentives (registries or bid auctions).
In general, the Decree grants a fixed tariff plus, in some cases, a specific premium, to incentive net electricity fed into the grid. The fixed tariff is different according to each source, technology and capacity range considered. Power plants with a capacity > 1 MW can only receive the incentive (fixed tariff minus electricity hourly zonal price, plus premiums if foreseen). Power plants with a capacity ≤ 1 MW can receive, instead of the incentive, a feed-in tariff composed by the fixed tariff plus, in some cases, a specific premium.
In the Dutch Auctions the maximum requested value of the tariff cannot be higher than a 2% discount of the reference value and the minimum value cannot be lower than a 30% discount of the reference value. The incentives last for the average conventional plant life of each typology of power plant. All the support schemes are managed by GSE (the Manager of Energy Services, a governmental company that provides incentives).
New, fully reconstructed, reactivated or empowered wave and tidal energy power plants can access directly to incentives if their capacity is not greater than 60 kW, otherwise they must apply for access to Registries.
* If the power plant is built by the Public Administration the maximum capacity eligible to direct access is doubled (120 kW)
For wave and tidal energy power plants, the total annual capacity (MW) eligible to access to Registries from 2013 to 2015 and so to obtain the incentives is indicated in the below table:
If the total installed capacity in a certain year is less than the capacity to be supported in that year according to the Decree, the residual capacity can obtain the incentives in the following year.
The wave and tidal energy rebuilt power plants can only access directly to incentives and their capacity must not be higher than 60 kW. The new Decree does not provide Dutch auction for wave and tidal energy power plants.
For new wave and tidal energy power plants entering into operation in 2013, the incentives are defined as follows:
For wave and tidal energy power plants entering into operation in 2014, the value of the fixed tariff is curtailed of 2%. For plants entering into operation in 2015, the tariff is curtailed of 2% compared to that in 2014.
The public/private consortium SEAPOWER Scarl, formed by a private company and the University of Naples, thanks to the collaboration between ADAG applied research group of Department of Aerospace Engineering, University of Naples “Federico II” and Eng. Nicola Giorgio Morrone, developed one of the most attractive projects of the last period in the field of renewable energy production using marine sources, named GEM: The Ocean’s Kite (see: www.dias.unina.it/adag/ select research, renewables and then GEM)
The SEAPOWER public/private consortium will also set up and manage a real field laboratory in the Strait of Messina opened to Italian and to foreign companies for testing their prototypes in the Messina Strait. The laboratory will provide assistance in deploying the devices, data handling and certification for the prototypes installed and tested in the area available to the consortium. The consortium is waiting for the final permit to build the laboratory.
Finally, Polytechnic of Turin has developed a small demonstration unit for wave energy production named ISWEC.
GEM project
The patented concept consists of a submerged floating body linked to the seabed by means of a tether. This hull houses electrical generators and auxiliary systems. Two turbines are installed outside the floating body and are exposed to the external currents.
Due to a relatively safe and easy self-orienting behaviour, GEM, The Ocean’s Kite, is a good candidate to solve some problems involved with oscillating and reversing streams, typical of tidal current. An additional advantage of its configuration is related to the possibility of avoiding the use of expensive submarine foundations on the seabed, because these are replaced with a flexible anchorage. Releasing the anchorage cable allows the system to pop-up for easy maintenance. A special diffuser has been designed to increase the output power for very low speed currents.
After several numerical investigations, a series of experimental tests on two different models has been carried out in the towing tank of the Department of Naval Engineering at the University of Naples.
The models tested were completely instrumented so that a dynamic behaviour and the off-nominal working conditions were investigated.
The real scale prototype system of 100 kW with 5 knots of water current speed has been built and has been deployed nearby Venice in a very slow speed current of about 3 knots, downscaling the power to 20 kW.
This prototype has been built by a consortium of Venetian companies thanks also to a financial contribution of Veneto Regional Authority.
The real field test has demonstrated the fully correspondence of the system behaviour with respect to what had already been measured on the 1:5 model during the test campaign in naval towing tank.
GEM: Artist impression and real scale prototype
FRI – EL SEA POWER System
Sea Power is a new groundbreaking project which consists of a vessel or pontoon, moored to the seabed, to which several lines of horizontal axis hydro turbines are attached. The same pipes, connecting the turbines through cardanic joints providing the necessary flexibility to the system, transfer the power captured from the water on board of the pontoon. Pipes are here connected to electrical permanent magnet generators (PMG) that are kept out of the water in order to simplify and diminish their maintenance. The electric generators transform the power carried by the transmission lines into electrical energy, which can be directly fed into the grid through an undersea cable, connecting the individual floating structures to a submarine hub, which in turn is connected to the shore by a single submarine cable. Alternatively, the systems can be installed offshore far away from the coasts and hydrogen can be produced with the electricity generated by the turbines.
After several numerical simulations, a first validation of the studies has been made by testing a prototype of the system in the water towing tank of the Naval Engineering Department of the University of Naples “Federico II”. Soon after the controlled tests, a series of open water prototypes tests has been carried out in the Strait of Messina, in order to check if the system works well in real conditions.
In July 2008, a small-scale of the Sea Power prototype (6 kW - 2.5m/s) was launched and in 2009 later another bigger prototype (20 kW - 2.5m/s) was tested in the same waters. The final system will be designed to be installed in rivers.
THE KOBOLD TURBINE
The Kobold Turbine is conducted in collaboration with “Ponte di Archimede international Spa”, a company that works in the field of research and development into alternative and renewable energy sources, specialising in the environmental aspects of this work.
The Kobold consists of a submerged vertical-axis turbine for exploitation of marine currents installed in the Strait of Messina, 150 metres off the coast of Ganzirri, since 2002. The realization of the Enermar prototype has been financed by Ponte di Archimede Company, together with a 50% fund paid by the Sicilian Region
Administration (Regione Siciliana), in the framework of European Union Structural Funds. This project has been disseminated among the developing countries in which the United Nations Industrial Development Organization (UNIDO) operates and three first countries that expressed interest. These countries were the People’s Republic of China, the Philippines, and Indonesia. A joint-venture was created, under the auspices of UNIDO, between “Ponte di Archimede” and the Indonesian Walinusa Energy Corporation.
A prototype is being built and it will placed on the Lomboc Island (the island immediately at east of Bali), where it could feed energy to a small village. The Indonesian plant will have blades length 7 m, (chord 0,4 m) and diameter 5 m (intercepted area 35 m2). The power could be about 120-150 kW.
Ponte di Archimede International has signed an agreement with the Dutch company Bluewater to develop the Bluetec device with the scientific and technological support of ADAG Group from University of Naples “Federico II”. This floating device will hold four Kobold turbines for a total power of about 1 MW and will represent a single unit of a possible farm made by several Bluetec systems. Towing tank experiments have been carried out both at Wageningen facilities and at University of Naples.
ISWEC Project
Sea waves are one of the most interesting and well distributed renewable energy sources in the world. At the current state of the art, all the existing sea wave energy conversion systems are designed to operate offshore, mainly in the oceans where the waves’ height is definitely high. In the Mediterranean Sea, waves are generally low, except under particular meteorological conditions. Thus, it is necessary to develop devices that can exploit other properties of the waves instead of their height, like wave slopes.
The mechanical conversion system, called ISWEC, that will be used for the development of the project has been analysed by Politecnico di Torino and results show that the system possesses good potential for energy conversion.
ISWEC device is composed mainly of a floating body with a slack mooring to the seabed. The waves tilt the buoy with a rocking motion that is transmitted to the gyroscopic system inside the buoy. The gyroscopic system is composed of a spinning flywheel carried on a platform. As the device works, the gyroscopic effects born from the combination of the flywheel spinning velocity φ˙ and the wave induced pitching velocity δ˙ create a torque along the ε coordinate. Using this torque to drive an electrical generator, the extraction of energy from the system – and therefore from the waves – is possible.
Trials at various levels will be carried out: in the first phase, a set of “dry tests” will be carried out on a controlled position mobile platform; in the second phase, a series of tests will be carried out in a tank, with suitably generated and controlled waves. Finally, the system will be placed and tested on Pantelleria Island.
ISWEC drawing and scaled prototype in testing site
Italy