Dear EarthTalk: Can airplanes be run on cleaner fuels or be electric powered? Are there changes afoot in the airline business to find cleaner fuels? -- Reema Islam, Dhaka, Bangladesh

Given air travel’s huge contribution to our collective carbon footprint—flying accounts for about three percent of carbon emissions worldwide by some estimates—and the fact that basic passenger and cargo jet designs haven’t changed significantly in decades, the world is certainly ready for greener forms of flying.

But since air travel emissions were not regulated under the Kyoto Protocol, the international agreement signed in 1997 that set binding targets for reducing greenhouse gas emissions, the friendly skies aren’t much greener than they were a few decades ago. And most national governments have been reluctant to impose new environmental restrictions on the already ailing airline industry.

Nonetheless, some airlines and airplane manufacturers are taking steps to improve their eco-footprints. Southwest and Continental have implemented fuel efficiency improvements, waste reduction programs and increased recycling, and are investing in newer, more fuel efficient airplanes. Another airline on the cutting edge of green is Virgin Atlantic, which made news in early 2008 when it became the first major carrier to test the use of biofuels (liquid fuels derived from plant matter) on passenger jet flights. Now Air New Zealand, Continental, Japan Airlines (JAL), JetBlue, and Lufthansa are also testing biofuels.

Even airplane maker Boeing is getting in on the act by developing a carbon-neutral jet fuel made from algae. Boeing’s newest commercial jet, the much vaunted 787 Dreamliner (now in final testing before late 2010 delivery to several airlines), is 20 percent more fuel efficient than its predecessors thanks to more efficient engines, aerodynamic improvements and the widespread use of lighter composite materials to reduce weight. Airbus is also incorporating more lightweight composite materials into its new planes.

On the extreme end of the innovation spectrum are zero-emission airplanes that make use of little or no fuel. The French company, Lisa, is building a prototype small plane, dubbed the Hy-Bird, that uses solar power (via photovoltaic cells on the elongated wingspan) and hydrogen-powered fuel cells to fly with zero emissions—and nearly no engine noise. The company claims the Hy-Bird is the first 100 percent eco-friendly plane, and is readying a round-the-world flight punctuated by 30 event-filled stopovers.

Even more unusual is the proposed fuel-free plane dreamed up by Mississippi-based Hunt Aviation. The company is working on a prototype small plane that harnesses the natural forces of buoyancy (thanks to helium-filled pontoons) for lift-offs and gravity for landings—along with an on-board wind turbine and battery to power everything in between—to achieve flight without any fuel whatsoever.

Don’t look for these futuristic planes on airport runways anytime soon. It will likely be decades before this technology filters its way up to the big leagues. Until then, take a train or bus instead. If you must fly, compensate for your flight’s emissions by buying a “carbon offset” from TerraPass or CarbonFund.org, which will use the money to fund alternative

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Just about anyone who flies on a commercial airline in the U.S. is aware of the volume of trash generated in the course of an average flight.  Drinks cans, plastic bottles, beverage cups, paper napkins, newspapers and magazines are testament to how much waste we all can generate in the course of a few hours.

In fact, the average airline passenger generates 1.3 lbs. of waste per flight, and in 2008 airline passenger trips in the U.S. generated over 881 million tons of waste, according to the consumer watchdog web site ResponsibleShopper.org .

“Nearly 75 percent of this waste is recyclable,” the consumer group says. “However, only about 20 percent is recycled.”

In a new report - What Goes Up Must Go Down: The Sorry State of Recycling in the Airline Industry - ResponsibleShopper.org rates the recycling efforts and programs of major U.S. airlines.  US Airways and United Airlines fail completely when it comes to reducing waste.  Delta and Virgin rank highest – but even their grades are nothing the average college student would write home about.  Here’s the complete list:

Ranking of airline recycling programs from best to worst

1. Delta Airlines (B-)

2. Virgin America (B-)

3. Virgin Atlantic (C)

4. Southwest Airlines (C)

5. Continental Airlines (D)

6. JetBlue (D)

7. American Airlines (D)

8. British Airways (D)

9. Air Tran (D)

10. United Airlines (F)

11. US Airways (F)

ResponsibleShopper.org is an online publication of Green America, which describes itself as America's "leading green economy organization, advancing marketplace solutions for our country’s most serious social and environmental problems.”

Green America said that in addition to the dismal recycling policies of the airlines, “on-flight research identified that some airlines are not actually implementing their stated policies in the air.  As a result, Green America is calling on passengers nationwide to respectfully ask flight attendants if materials on their specific flights are being recycled.”

Victoria Kreha, lead researcher on the ResponsibleShopper report, says “the good news is that airlines are starting to pay attention to recycling; the bad news is that they have a long way to go to improve the situation.  Fortunately, airlines can overcome any of the challenges to creating in-flight recycling programs, including employee education and involvement, knowledge of the type of waste produced, and a time- and space-efficient system.”

Green America urged the airline industry and its trade associations to encourage member airlines to adopt goals for recycling or composting that will lead to overall industry resource recovery of 50 percent of waste by 2012, and zero waste by 2020.   “This goal can be achieved through greater use of recyclable and compostable materials on flights, and increased coordination between airports and airlines in separating and processing waste,” according to Green America.