ExxonMobil Corp, Irving TX, has announced the completion of the Q-Max liquefied natural gas (LNG) carrier, Mozah, a ship that carries up to 80 percent more cargo, yet requires approximately 40 percent less energy per unit of cargo than conventional LNG carriers.
The technologies, developed by ExxonMobil in conjunction with joint venture partner Qatar Petroleum, include increased ship size, onboard reliquefaction units, slow-speed diesel engines, twin propellers and rudders, large ship-board LNG tanks, hull antifouling protection, and fire-protection systems.
ExxonMobil said the Q-Max carriers are longer than three football fields and tower 20 stories tall from keel to masthead. With a total capacity of up to 266,000 cubic meters, each ship carries enough natural gas to meet the energy needs of 70,000 US homes for one year.
In addition to increasing the size of the ship, a major initiative was undertaken to design, test, and implement the on-board reliquefaction plant that re-liquefies natural gas that is vaporized during transit, re-injecting it as liquid into the cargo tanks rather than using it as vaporized gas to power the tanker itself--allowing for delivery of nearly 100 percent of the cargo.
Exxon said the reliquefaction is particularly beneficial for the long-haul voyages from Qatar to Europe and the Americas. The on-board plant created an opportunity to shift from steam boilers and turbines used for propulsion by conventional LNG ships to slow-speed diesel engines.
Qatar Petroleum and ExxonMobil are shareholders in a Qatar joint venture, Qatargas, that will charter the Mozah and five other Q-Max carriers to supply LNG from new liquefaction trains in Qatar. In addition to the vessels to carry LNG to market, ExxonMobil in partnership with Qatar Petroleum, is employing new technology in Qatar to build four large LNG production facilities and is participating in the development of LNG regasification terminal projects in Italy, the United Kingdom, and the United States, according to the ExxonMobil information.