Ryanair announced the purchase of 27 more Boeing 737-800s valued at $1.9 billion Thursday, bringing its total firm orders for the U.S. made planes to 308.
Ryanair's total fleet including planned disposals will be 262 by 2012, Europe's largest low-fare carrier said in a press release.
The move adds to the Irish airline's claim to have the youngest and most fuel-efficient fleet of all the major airlines, by bringing the average age of its planes to 2.5 years.
The reduction of emissions has become a key requirement for airlines over recent years due to concerns about their effect on the environment. The new Boeing planes will also be fitted with blended winglets, which are designed to further reduce CO2 emissions.
Ryanair also announced it has cut 20 pounds ($40) off all return fares for one week in conjunction with the announcement.