The Federal Aviation Administration (FAA) reported that last year, U.S. and foreign air carriers transported an estimated 161.8 million passengers between the United States and the rest of the world. The FAA estimates there will be one billion passengers in 2024. So how does the aviation industry handle the prospect of a billion passengers with rising fuel prices, crowded airspace, out-dated systems, and increasing environmental concerns? The answer is new technology that is both in use today, and on the horizon for air travel tomorrow.
Green aviation is about taking responsibility for the impact of aviation on the environment, which includes carbon footprint, other emissions, and noise. Last year, ASTM International, the global standards body that oversees jet fuel specification in North America, published new rules allowing the use of biofuels (made from living things or the waste they produce) on all commercial flights. The revision to standard D7566, Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, includes requirements for synthetic fuel components manufactured from hydroprocessed esters and fatty acids (HEFA) produced from renewable sources. The standard allows new components to be manufactured from jatropha, camelina, and fats, and combined with conventional aviation jet fuel.
Biofuel (or drop-in fuel) must have energy density equal to or greater than conventional jet fuel, and must be able to function in desert heat or in cold temperatures at 40,000 feet. Boeing has been leading the push for approval of synthetic paraffinic kerosene (Bio-SPK) jet fuel, and is also testing algae- and camelina-based fuels.
France-based Airbus also has been in the forefront of developing and testing new jet biofuels. They are helping to develop the second generation of biofuels, known as biomass, which avoid competing with food resources. Some options being investigated are algae, woodchip waste, camelina, yeast, and halophytes such as salicornia (plants grown in salt water).
Boeing recently flew the world’s first commercial airplane from Everett, WA to Paris using biologically derived fuel. The 747-8 Freighter’s four General Electric GEnx-2B engines were powered by a blend of 15% camelina-based biofuel mixed with 85% traditional kerosene fuel (Jet-A). Boeing did not need to make any changes to the airplane, its engines, or operating procedures to accommodate the biofuel.
Carbon dioxide (CO2) is produced as a result of fuel consumption, so with reduced fuel use comes an equivalent reduction in carbon dioxide emissions. Another key emission standard for commercial jetliners is nitrogen oxides (NOx). Specific regulations have already been set for future airplanes, using a complex formula that is based on the thrust ratings of an airplane’s engines. The Boeing 787 is being designed to be more than 30 percent better than today’s 767s — and it will be better than the future, more stringent regulations being incorporated by the Committee on Aviation Environmental Protection (CAEP).
Other energy sources such as solar power and energy harvesting also are being investigated for aircraft. While even the most efficient solar panels would still not be enough to propel a large aircraft, solar energy could provide electricity onboard the plane once it has reached altitude, or it could help reduce fuel burn and emissions during ground operations at airports.
Likewise, energy harvesting also has applications within the aircraft as an alternative power source. The body heat a passenger gives off when seated for a number of hours could be collected by the seat, and combined with energy collected from other sources like solar panels to fuel cabin appliances or power cabin lights.