Airplanes may only contribute about two percent of atmospheric greenhouse gases but it does create some, especially in the areas leading right up to the runway where planes descend. Jet fuels give off not only carbon dioxide emissions when incinerated but also nitrogen oxides, soot, sulfate particulate and other substances which can have an environmental impact. A study of aircraft emissions near airports published last year in the journal Environmental Science & Technology found that communities located 10 miles away from Los Angeles International Airport saw anywhere from two times to four times the normal amount of airborne particulate throughout most of the day.
Some researchers worry that some airplane pollution poses a very direct threat to human health. Scientists at the Massachusetts Institute of Technology recently released a study finding that 10,000 deaths per year were attributable to airborne pollution from airplanes, much greater than the number of those who die in plane crashes. The research suggests that 2,000 of those individuals are affected by takeoff and landing emissions while the rest succumb to health conditions caused by cruising altitude emissions, which are blamed for respiratory and cardiovascular diseases.
A global framework for reducing aviation greenhouse gas emissions has been under development at the UN’s International Civil Aviation Organization (ICAO) but still won’t be officially in place until at least 2016. The inaction by the ICAO has created a regulatory vacuum which the European Union is trying to fill by implementing an emissions trading system for aviation which applies to most of the air traffic which take off and land within the EU. There has also been voluntary activity within the industry as members of both the International Air Transport Association (IATA) and the Air Transport Action Group (ATAG) have committed to certain standards in stabilizing emissions and improving fuel efficiency in the next few years.
The issue of sustainability in aircraft fuel, in which energy security concerns also play a role, has led to the pursuit of alternative fuel development. The Federal Aviation Administration has stated that it will work towards enabling the American aviation industry to utilize one billion gallons of alternative fuels from renewable sources each year by 2018. The agency helps to coordinate a number of programs, including the Partnership for Air Transportation Noise and Emissions Reduction (PARTNER) and the Commercial Aviation Alternative Fuels Initiative (CAAFI). The United States’ Aviation Greenhouse Gas Emissions Reduction Plan seeks to achieve carbon-neutral growth for American commercial aviation by 2020. NASA is another federal agency involved in alternative jet fuel development, taking part in tests of non-petroleum-based jet fuels at Dryden Flight Research Center along with 11 other research groups.
A lot of research and development into alternative fuels for aircraft has focused on biofuels, which has also been an area of focus of automakers. Last January, Boeing Co. (NYSE:BA) announced a series of developments in creating green diesel that cuts carbon dioxide emissions in half compared to conventional fossil fuels. The company also unveiled a breakthrough in the effective biofuel conversion of halophytes, shrub like plants indigenous to the Middle East which grow in seawater found near desert terrain.
Relying on plant-based sources for biofuels poses a concern to some. In June 2011, the World Bank issued a report which indicated that expanding crop-based biofuels could push up the prices of staple crops, making it more difficult for the world’s poor to afford food. Recently, United Airlines announced that it had developed a biofuel derived from both farm waste and animal fats which the company plans to start using in its aircraft this summer. The company which developed that biofuel, California-based Fulcrum BioEnergy, has also developed technology capable of converting most municipal solid waste into low-carbon transportation fuels.
Regardless of the biomass feedstock, many of these biofuels are produced through the Fischer-Tropsch process. This chemical technique converts synthetic gas, or syngas, formed from a mixture of carbon monoxide and hydrogen into hydrocarbon chains that store chemical energy densely enough to serve as an aviation fuel. When coupled with techniques like gasification for turning a variety of carbon sources into syngas, Fischer-Tropsch holds the key to converting just about any renewable biomass into biofuel.
Perhaps the airplanes of the future might not even need fuel, at least not the conventional liquid jet fuel which has been in use for decades. The automotive industry has been pursuing electric vehicles, propelled by motors powered by an electrical charge stored on a battery, so it’s no surprise to some activity in electric airplane development.
Most recently, a pair of electric planes were able to make the English Channel crossing on a route made famous more than a century earlier by Louis Blériot, the French aviator who became the first person ever to make that crossing. French airplane manufacturer Airbus Group SE (EPA:AIR) sent a two-seat demonstrator plane called the E-Fan, which is powered solely by lithium batteries, across the Channel from Lydd, England, to Calais, France, near the beginning of July. Later on, however, it was learned that an individual French aviator, Hughes Duval, had beaten Airbus to the punch by about 12 hours, flying his own electric battery-powered Cri-Cri plane. A couple of points of controversy exist here as Duval did not have permission to take off from Calais, requiring him to use a fuel-driven plane to provide a tow during takeoff before separating at cruising altitude. As well, the Airbus E-Fan was aloft for a longer period of time of 36 minutes, more than twice Duval’s flight period of 17 minutes.
Not content with lithium-ion battery-powered planes, there is one corner of the aviation industry which is trying to take advantage of the altitude of air travel for solar energy-powered flight. Also in early July, the Solar Impulse solar-powered aircraft completed the eighth leg of a 13-leg journey across the world when it traveled from Japan to Hawaii, making a 5,100-mile trip. The craft, which is more than halfway through its return trip to Abu Dhabi, spent 118 hours, nearly 5 days, in the air, subjecting pilot Andre Borschberg to some significant physical and mental health concerns. Incredibly, the Solar Impulse made most of the trip with damaged equipment as it was discovered that its batteries were damaged by heat on the first day of the trip after the batteries were over-insulated. The plane will not be ready to take off again until the beginning of August, giving the team only a few more weeks to complete their journey before September wanes and less daily sunlight becomes a concern.