MIAMI, FL — Royal Caribbean Cruises Limited, the world's second largest cruise operator, has cut fuel consumption by about 4 percent with better designed ships, smarter sailing practices and energy efficiency measures that include installing solar window film in every ship in the fleet.

Royal Caribbean Ltd. released its 2009 Stewardship Report on Monday. The firm's second report primarily covers the environmental, safety, security, medical and public health efforts of three company brands: Royal Caribbean International, Celebrity Cruises and Azamara Club Cruises.

RCL also owns and operates CDF Croisières de France and Pullmantur Cruises, and has a 50 percent investment in TUI Cruises, a joint venture with TUI AG of Germany.

In 2009, almost 4 million passengers traveled aboard RCL's 38 ships to 400 destinations. According to its report, the firm used 3.7 percent less fuel per available passenger cruise day (APCD) to do so than in 2008 -- beating a year-over-year reduction goal of 2 percent and consuming about 30,000 metric tons less in fuel than planned. The reduction is roughly equivalent to taking 13,000 mid-sized sedans off the road for a year, the cruise ship company said.

Since 2007, the company has reduced fuel consumption by 7 percent per APCD. An APCD is the number of lower berths on a ship times the number of days that those berths are available to passengers per year. A 2,000-berth ship that is in dry-dock for five days out of the year, has an APCD of 720,000 -- i.e. 2,000 x 360.

The firm has an immediate goal of reducing fuel consumption per APCD by at least 2.5 percent each year and plans to set higher targets as new technologies develop.

"In our daily operations, we face two primary energy challenges: How to efficiently utilize clean, secure and affordable energy, and how to minimize our impact on the environment related to our air emissions and greenhouse gas (GHG) footprint," RCL Chairman and CEO Chairman and CEO Richard D. Fain said in the report.

Aboard a ship, fuel is used not only to propel the vessel, which accounts for about 60 percent of consumption, it also goes toward HVAC (about 11 percent), hotel and lodging related purposes (about 16 percent) and auxiliary engines (about 13 percent), RCL said.

Although fuel consumption decreased for a second straight year, greenhouse gas emissions rose slightly between 2008 and 2009.