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In a world searching for steadiness in the energetic supplies, the necessity of a sources diversification encouraged the development of more and more advanced technologies for the production, conversion and transport of fossil fuels, that remain decisive in the energetic planning of every nation thanks to their relative ease of conservation. The call for alternative solutions to oil, due also to the unstableness of its price, arranged that in most recent years the research interest rapidly moved in the direction of development of technologies for the Natural Gas exploitation, abundant in many areas of the world not only for its utilization in the near markets, but with the intention of making it available to far users.
The main criticalities in the Natural Gas exploitation are transport and storage. The really effective methods are two:
1) in gas state through gas pipeline
2) in liquid state at -165°C through ship (LNG)
In the first case, the most traditional, there is the advantage of a general simplicity and cheapness of plants, while the cons relaet to the unavoidable geographical limitations (impossibility to cross oceans), the storage difficulty of fuel in gas phase and most of all, the dependence from International accords among the countries crossed by pipelines, including the possible political instabilities (e.g. siberian pipeline through Ukraina) that do not allow the complete peace of mind of supplies.
In the second case, the most innovative, the main cons are to be found in the high building and maintenance costs of criogenic plants (liquefaction, LNG carriers and regasification) and in finding proper areas for regasificators, that can’t be placed very far from the gas use dock (otherwise it would be necessary to create new linking pipelines to the main network).
Nevertheless benefits of this new technology are many, to the point that it is the only real possibilità for a greater indipendency from oil as Energy source; first of all, to have regasification plants means for the user toh ave access to more suppliers, increasing the contractual power and for the producers to grant access to markets that were once unreachable.
Therefore, gas in liquid phase can be easily stored, provided that there are highly engineered plants, and this grants a greater continuity of supplies.
In Europe there is a growing interest towards the use of natural gas, both with development plans of new pipelines and with regasification plants. Unfortunately, within the EU, it seems ther is not an energetic common plan to coordinate the investments and the creation of facilities to serve the whole community, every country seems to move in an autonomous way without a real vision of the whole. We go from Spain, that rapidly built 5 regasificators, without releasing itself from the pipeline network that comes from Algeria, to Italy, that even if it has been among the first to invest in a regasificator plant (Panigalia – La Spezia), in years strengthened the pipeline network linking it to Siberian and Mediterranean producers (Algeria, Libya, Russian Federation), that in recent times showed how important it is to have alternative sources.
LNG Cycle
LNG cycle can be summed up in few points:
- Gas extraction
- Liquefaction and Storage
- Transport through LNG carrier ships
- Storage at destination
- Regasification and injection in network
In liquefaction phase, natural gas (a mix of variable composition of methane, ethane, propane, butane) is refined, so once that it is regasified, it can be injected directly in the network.
The importance of passive insulation
Being the whole LNG production process based on cryogenic technologies (the final temperature of the transported liquid is -165°C), it becomes decisive the choice of insulating materials.
The Polyurethane choice.
Within the universe of insulating materials, only three are suitable to work in cryogenic conditions: Perlite, cellular glass (inoganic materials) and Polyurethane (organic material). Perlite has the consistency of a medium granulometry powder and it is mainly used as filler for the insulation of tanks walls; cellular glass is mainly used for tanks foundation and for those parts of the plants that are subject to cold/heath.
Polyurethane is used on the other hand for the main parts of plants, and for insulation of tanks on LNG carriers. The preponderance of polyurethane in LNG technology is mainly due to:
- Easiness/Quickness of positioning (non toxic material)
- Excellent insulation performances together with high mechanical properties (best compromise)
- Versatility in the application (pre-formed, casting, spray)
- Excellent compatibility with fibre-glass for the creation of composites with high performances R-PUF (application in LNG carriers)
- Warranty of effectiveness in time (thanks to a practically unlimited steadiness)
Conclusions
- In a world searching for stableness of energetic supplies, it is reasonable to think that more and more countries will try to have regasification plants, that grant a wider freedom of source selection and a reduction of the pipeline supply dependence, more liable to uncertainty of political choices of countries that they cross.
- In the same time, producer countries, once excluded from the gas lines because of the distance from users (e.g. Nigeria e Yemen), are equipping themselves with liquefaction plants that will grant them to exploit their natural resources to serve markets that were once unapproachable.
- Thanks to the use of more and more performing insulating material, especially polyurethane and especially on LNG carriers, distances between these two groups rapidly shorten, creating a real gas global market in which Qatar and Nigeria for example will serve both USA, China and Japan.
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