adriatic LNG terminal

The Adriatic LNG Terminal is the first ever offshore Gravity Based Structure (GBS) for unloading, storing and regasifying Liquefied Natural Gas (LNG).

Located offshore of Porto Levante, in the northern Adriatic Sea, the terminal has a regasification capacity is of 8 billion cubic meters of natural gas per year (775 million cubic feet per day), or approximately 10 percent of Italy’s current natural gas requirements.

The terminal is a strategic infrastructure for Italy as it opened a ne gas route totally independent by the pipelines, thus representing a remarkable step towards the diversification and supply of energy supplies.

Eighty percent of the Terminal capacity will be utilized by Edison for a period of 25 years, to regasify LNG imported from Qatar’s North Field, as part of a supply agreement with RasGas II.

The facility is owned and operated by Adriatic LNG Terminal company where Edison has a 7.3% stake. The other shareholders are ExxonMobil Italiana Gas (70.7%) and Qatar Terminal Company Limited (22%). 

The components of the Terminal include:

• the concrete Gravity Based Structure (GBS)
• two LNG storage tanks inside the GBS
• the regasification plant
• facilities for mooring and unloading LNG vessels
• living quarters
• a pipeline connected to the mainland

The main feature of the Adriatic LNG Terminal is its concrete Gravity Based Structure (GBS), a massive construction that rests on the seabed at a depth of about 29 meters. Made of 90,000 cubic meters of cement and 30,000 tons of steel reinforcement, the GBS was built at the Campamento construction site in the Bay of Algeciras in Southern Spain.
The GBS is 180 mt. long, 88 mt. wide and 47 mt. high: it’s larger than two soccer fields and as high as a ten-floor building most of which is under water.

Inside the GBS are two LNG storage tanks, each with a capacity of 125,000 cubic meters, made of steel with 9% nickel to provide cold temperature performance. Specially designed using ExxonMobil patented modular technology they were built at one of the world’s largest shipyards, in South Korea.
For transport reasons, each tank was designed in 3 modular parts, which were then shipped to the Campamento construction site in Spain. There they were installed in the Terminal’s Gravity Based Structure using custom-designed systems and connected to each other and the regasification plant by special welding techniques.
LNG is stored in the tanks at atmospheric pressure and at the temperature of minus 162° C, in order to keep it in its liquid form.

The Terminal’s regasification plant is located on the top of the GBS. It consists of four LNG Open-Rack vaporizers that operate using the natural heat of sea water, an energy recovery LNG vaporizer that reutilizes heat from the gas turbines, two cryogenic compressors, four pumps used to lift the LNG from the tanks, and five send-out pumps that send the gas through the vaporizers and into the external pipeline.
The plant also includes a number of auxiliary facilities, such as gas turbine-powered electricity generators and the electrical control center.

The terminal also includes facilities for mooring and unloading LNG vessels.
Key components of the berthing facilities are the “Mooring Dolphins” constructed in the Arsenale shipyard in Venice. These structures are designed to safely accommodate a wide range of different sized LNG carriers.

Each Mooring Dolphin structure consists of a base (reinforced concrete base slab, walls and roof slab approximately 7 meters tall), two reinforced concrete columns rising above base (approximately 28 meters tall) and a steel truss deck (63 meters long and 8,5 meters wide) sitting on top of the columns.
The structures (9.000 tons each) were towed for 50 kilometers from Venice to the Adriatic Sea, placed on the sea floor on both east and west ends of the GBS and then connected to the terminal by steel walkways.
In addition, for offloading LNG carriers the terminal has installed specially designed loading arms that can be connected and operated in a much wider range of sea states consistent with an offshore location. These arms transfer the LNG from the vessel to the pipes that carry it to the terminal storage tanks.
The entire system was designed and tested to ensure safe operation during mooring, unloading and departure operations, even in severe weather conditions.

The operating and maintenance staff on the Adriatic LNG Terminal are on hand 24 hours a day, 7 days a week and therefore every effort has been made to provide them with a comfortable environment for both working and relaxing.
The specially designed personnel module, housing up to 60 members of staff, is therefore a self-contained facility that includes living and sleeping quarters and the Terminal’s state-of-the-art Control Room. Here, thanks to highly advanced control communication, video camera and radar systems, operators can monitor every aspect of the Terminal’s operating cycle, from the storage tanks to the metering station, while also maintaining contact with the Shore Base, passing vessels and marine authorities.
The Terminal crew’s living quarters, on the other hand, include a fully staffed kitchen, medical facilities, a laundry and heliport, as well as communal areas for enjoying meals or simply relaxing.

After being reconverted to its original state, the gas then flows into the pipeline system, connecting the terminal with the mainland and then with the national gas distribution network, ready to be distributed to end users.
Designed and built by the Italian company Snamprogetti, a 30-inch diameter, 40-km long pipeline transports the gas from the terminal 15 km offshore and then 25 km onshore to the metering station near Cavarzere, in the province of Venice.
From here, another pipeline, 84-km long and owned by Edison Stoccaggio, transfers the gas to a tie in point with the national distribution network near Minerbio, in the province of Bologna.

The Shore Base is the critical link with the offshore Terminal. All the supporting activities to handle materials and personnel to and from the Terminal are coordinated from this location.
It is a 5000 square meter facility located along the Po di Levante River, in the municipality of Porto Viro (Rovigo).
It includes a warehouse for all spare parts and supplies, offices, telecommunications systems for constant communication with the Terminal and a dock for the supply boat to the Terminal.

New energy for Italy: the Adriatic LNG terminal.