Numéro : 2624 - Year : 2012
Propulsion with natural gas: a new environmental, economical and safety challenge
Ludovic GERARD, CMA Ships – Marseille
Jean-Baptiste BOUTILLIER, Mathieu RENAUD, CMA Ships – Marseille
Yannick DAVIGO, Bureau Veritas – Direction technique Marine – Sécurité du Navire – Neuilly sur Seines
Christophe CAPITANT, Blandine VICARD, Bureau Veritas – Direction technique Marine – Sécurité du Navire – Neuilly sur Seines
Rising fuel costs – 700$/t of HFO in march 2012 - and the revision of MARPOL Annex VI by the International Maritime Organization (IMO) may trigger major evolutions in the propulsion systems of ships other than gas carriers. This regulation will enforce ECA (Emission Control Areas) where SOx emissions will have to be reduced tenfold.
Shipowners then have two options:
- Use a “clean” fuel such as natural gas,
- Install exhaust gas cleaning systems.
The lower price of natural gas compared to that of fuel oil and the associated low pollutant emission argue for the first option, but such modification has to be considered taking into account economics, logistics and safety issues.
The profitability of the LNG option is to be assessed based on the total cost of gas propulsion i.e. initial investment and life-cycle costs such as fuel prices and maintenance costs. In addition, the possible variation of the gas prices with respect to fuel oil has to be considered: A detailed study carried out by CMA CGM on a container ship project will be detailed.
Gas logistics currently appears as crucial, since gas propulsion will mean regular gas bunkering operations: In order not to interfere with the commercial operations of the ship, bunkering will have to be as easy, cheap and short as possible without compromising safety. Several bunkering options will be described and discussed with regards to the size and type of the ship and the associated infrastructure and equipment.
Furthermore, the storage and use of natural gas on board non specialised ships create specific risks that should be addressed by IMO IGF Code – International Code of safety for ships using gases or other low-flashpoint fuels. However, this Code is not issued yet and a number of ship project are currently being developed based on the available draft or interim Rules and dedicated risk analysis: We detail a number of possible solutions identified in this process.
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