Business aviation’s global CO2 emissions are approximately 2% of all aviation
and .04% of global man-made carbon emissions. Business aircraft are operated for specific missions and fly efficient, direct routes between airports. Modern navigation equipment, combined with the latest technologies in aircraft and
engine design and operational best practices, provide for ever-improving fuel efficiency and reduced emissions.
In 2009 business aviation manufacturers and service providers, represented by the General Aviation Manufacturers Association (GAMA), and business jet operators, represented by the International Business Aviation Council (IBAC), jointly announced the Business Aviation Commitment on Climate Change, an aggressive program to address the industry’s carbon emissions by meeting the three following targets:
#1: Improving fuel efficiency 2% per year from 2010 until 2020
#2: Achieving carbon-neutral growth from 2020
#3: Reducing CO2 emissions 50% by 2050 relative to 2005
Basics of fuel burn
The rate of fuel burn depends its stage of flight: the land and takeoff cycle (LTO), considered all operation below 3,000 feet, and the cruise, climb and descent cycle (CCD) or operation above 3,000 feet.
Fuel burn for LTO includes taxi-out, takeoff and initial climb, and then final descent, landing and taxi-in. In the CCD flight cycle, fuel consumption includes climb-out above 3,000 feet to altitude, cruise and initial descent. An airplane uses significantly more fuel getting off the ground than cruising at altitude, but the farther the cruise, obviously the more fuel consumed. Other factors impacting fuel consumption include wind, weather and weight.
Aircraft Improvements
Learjet and Gulfstream offered the first production aircraft with winglets in the late 1970s. By reducing wingtip vortices, and therefore drag, winglets offer a 4 to 6 percent savings in fuel consumption and up to 6 percent reduction in carbon emissions, according to NASA. From the winglet to improved airframe design and increasingly more efficient engines, makers of civil aviation aircraft have over the years innovated new technologies that reduce both operational costs and environmental impact.
Automatic Dependent Surveillance-Broadcast (ADS-B) is a technology that allows for direct routes, reduces delays, and ultimately increases overall airspace capacity. Reducing flight time cuts down on fuel burn and emissions. What’s more, ADS-B devices are already available today, years ahead of the mandated implementation date. In addition, ADS-B receivers make electronic chart applications more useful and attractive for pilots, eliminating the need to produce heavy and wasteful paper charts.
Gulfstream’s newest family of aircraft, the G500 and G600, are powered by versions of the new Pratt & Whitney Canada PW800 series engine, which, along with the Gulfstream-designed wing, delivers fuel efficiency improvements of more than 10 percent over previous generation engines, fewer emissions, and less engine noise.
“Gulfstream has also has Federal Aviation Administration approval for RNP SAAAR, which stands for Required Navigation Performance Special Aircraft and Aircrew Authorization Required,” Bowman explains. “This feature allows precision vertical and lateral navigation guidance to within 0.1 nautical miles and allows improved use of preferred airspace routes which results in lowered fuel usage.
Alternative Fuels
Renewable jet fuel: Also called “biojet” or aviation biofuel, renewable jet fuel is a biomass-derived fuel that can be used interchangeably with petroleum-based aviation fuel. Certain biojet fuel can be blended up to 50% with conventional commercial and military jet (or aviation turbine) fuel.
The aviation industry is driving the research, development and deployment of commercially viable, sustainable alternative aviation fuels. Industry is partnering with authorities in Europe and North America to develop, certify and commercially implement such fuels within the next few years.
The following fuel categories are approved by the standard:
• Hydrogenated esters and fatty acids (HEFA) fuels derived from used cooking oil, animal fats, algae, and vegetable oils (e.g., camelina)
• Fischer-Tropsch fuels using solid biomass resources, e.g., wood residues.
• Synthetic iso-paraffin from fermented hydroprocessed sugar (SIP), formerly known as direct-sugar-to-hydrocarbon (DSHC) fuels. Only blends of up to 10% are permitted for this fuel
By using a blend of Honeywell Green Jet Fuel, derived from the camelina plant, Honeywell achieved the first ever transatlantic flight to be powered by a biofuel blend in June 2011, carrying a 20,000 kg Gulfstream G450 business jet from New York to Paris in a flight that apparently saved around 5.5 metric tons of net carbon dioxide and burned around 20 gallons less fuel.
Thinking Out Of The Box
Adding an electric drive to the airplane’s nose wheel may improve fuel efficiency during ground handling. This addition would allow taxiing without the use of the main engines. For instance, a company WheelTug has already designed such a device, that reduces the time an airplane spends on the ground, allowing it to spend more time in the air. The WheelTug system includes small electric motors in the nosewheels that enable an aircraft to drive forward and backward without using its engines or external tugs. This enables pilots to pushback and maneuver around the gate without tug or engine delays. The time savings can be dramatic — allowing airlines to get more out of their aircraft and passengers to get more out of their day.
Another possible reduction of emissions is the limitation of cruise altitude of aircraft. This would lead to a significant reduction in high-altitude contrails for a marginal trade-off of increased flight time and an estimated 4% increase in CO2 emissions. Drawbacks of this solution include very limited airspace capacity to do this, especially in Europe and North America and increased fuel burn because jet aircraft are less efficient at lower cruise altitudes.
Moreover, the era of electric aircraft is fast approaching. NASA is currently actively working on the Electric Propulsion Technologies, that can allow getting rid of fuel as we know it, and switch to electric power. NASA’s project LEAPTech is a key element of a plan to help a significant portion of the aircraft industry transition to electrical propulsion within the next decade. According to Mark Moore, an aerodynamicist at Langley, “LEAPTech has the potential to achieve transformational capabilities in the near-term for general aviation aircraft, as well as for transport aircraft in the longer-term.”
Conclusion
It can be argued that aviation industry is only in the starting stages on the path to achieving the effective emissions reduction. Research & Development of biofuels takes time, legislative action sometimes «gets stuck» in the hierarchy of international aviation organisations. However, with the right approach and consistent agenda on reducing CO2 emissions, including thorough emissions study & review by local aviation bodies in each sovereign state – aviation industry can surely consolidate the group efforts and get to a new level of tackling CO2 emissions.
