A California-based website has named two West Coast airlines, San Francisco’s Virgin America, and SeaTac’s Alaska Airlines, as the “greenest” air carriers in the country.

Greenopia said the fuel efficiency of the two airlines’ relatively young fleets of aircraft, their recycling and alternate fuels activity put the two airlines at the top of the list for their environmental efforts. Virgin was first on the site’s list. Alaska was second.

Virgin’s fleet of Airbus jets is the youngest in the country with an average age of two years. Virgin is a new airline that began with a new fleet in 2007 and that has expanded that fleet in subsequent years. Alaska’s fleet, at an average age of six years, is the youngest of the long-established airlines. New jets generally are more fuel-efficient than older planes.

The website praised Virgin’s efforts to allow passengers to offset the carbon emissions from their flights by offering them an opportunity to donate to a charity that funds energy efficiency projects. The airline’s efforts to clearly report its environmental efforts and effects on its site also won plaudits.

In addition to the relative fuel efficiency of fleet, Alaska earned praise for its efforts to operate its ground service vehicles with electric power and for recycling waste generated on its flights and in its offices and airport facilities.

The site wrongly gave kudos to Virgin America for demonstration flights using only biofuels. Virgin hasn’t conducted such flights, though an affiliated airline, Virgin Atlantic has conducted flights using a mix of biofuels and petroleum fuels. The site dunned Alaska for failing to explore using biofuels. Alaska, however, has signed a memorandum of understanding along with other airlines to buy biofuel from a Seattle-based fuel company. Altair Fuel.