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TerraPass Sponsored Series

Carbon Offsetting

Sustainability at 35,000 Feet: A Look at Business Aviation and Climate Change


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When Detroit’s Big Three automakers flew their corporate jets to Washington, D.C. in 2008, to plead Congress for a $25 billion bailout, those airplanes conveyed not just their contrite passengers but also a public image of corporate aviation as an excessive luxury -- how the "one percent" get around (including some preachy environmentalists).

Portraying this ill-advised PR blunder on the part of Detroit’s CEOs -- they could have at least made the trip in one airplane -- as emblematic of business aviation in general oversimplifies the role and importance of general and business aviation.

Still, for most of us it’s easy to look at a corporate jet as a limousine with wings. The purview of large corporations and overpaid CEOs. In fact, of the 15,000 business aircraft registered in the United States, only 3 percent are in use by Fortune 500 companies, according to the National Business Aviation Association (NBAA).

A scheduled airline runs most efficiently on a hub-and-spoke system, but scheduled air carriers serve only about 500 airports in the United States, and that number is declining. Most U.S. airlines only fly into 70 major airports. General aviation business aircraft have access to more than 5,000 and go where and when needed.

Business aviation includes everything from the traffic helicopter guiding your morning commute, to a piston single-engine, four-seater Cessna providing access to remote communities, to the sleek corporate jet flying non-stop from New York to Dubai. The types of aircraft represent a cross-section of the organizations that use them -- governments, NGOs, universities and businesses of all sizes.

Access, flexibility and specific use requirements make the case for business aviation. But at what cost? It takes a lot of fossil fuel to power a global aviation system. Even if general and business aviation is a small subset of the global industry, its carbon footprint is not insignificant.

Calculating fuel burn

Figuring carbon emissions from an airplane is essentially a function of determining how much fuel is consumed from engine start to engine shutdown. But unlike earth-bound modes of transportation, airplanes don’t consume fuel on a linear scale to distance traveled. 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.

It is certainly a more complex task than sticking the gas nozzle in your car and driving until the needle gets near “E," but calculating all the factors for proper fuel load on an airplane is part of the day-to-day routine of any pilot.

It gets a little trickier when we attempt to assess the impact burning that fuel has on climate and global warming.

Aviation and global emissions

According to the Air Transport Action Group (ATAG), the global aviation industry accounts for 2 percent of anthropogenic carbon dioxide emissions (some put the number at closer to 3 percent). General aviation, including aircraft used for business, represents only 0.20 percent of the 36 giga-tons of global annual CO2 emissions from burning fossil fuels (and making cement).

That tiny percentage is understandably how industry prefers to portray its contribution to climate change, but aviation is the fastest growing source of greenhouse gas emissions -- contributing about 13 percent of all emissions from the transportation sector. There’s more to the story than just aggregate percentages.

The troposphere, tropopause and stratosphere: Airplane emissions and the atmosphere

Modern jets cruise in the upper troposphere, which extends from ground level up to about 6.2 miles, and lower stratosphere, beginning at around 33,000 feet. The tropopause is the boundary layer between the troposphere and the stratosphere.

Along with carbon dioxide, jet engines emit water vapor (H2O), nitrogen oxides including nitric oxide (NO) and nitrogen oxide (NO2) (together termed NOx), carbon monoxide (CO), partially combusted hydrocarbons (volatile organic compounds or VOCs), particulates (soot), and other trace compounds.

According to the paper Calculating the Environmental Impact of Aviation Emissions by Dr. Christian N. Jardine of Oxford University, CO2 and H2O are the predominate emissions from aircraft, at about 70 and 30 percent respectively. Less than 1 percent each make up the rest of the emissions soup. Most of these emissions occur at high altitude.

The impact of CO2 emissions on climate is the same irrespective of its source. It makes no difference whether it comes from a power plant in Nebraska or a Learjet at 40,000 feet over Europe, the CO2 emitted mixes with the global atmosphere over many decades or even hundreds of years.

For NOx and H2O emissions, climate impact is localized and amplified at high altitude. Nitrogen oxides chemically react with light to form ozone (O3). The higher intensity of light in the upper atmosphere produces more ozone from NOx emissions, and these emissions have more influence on climate than those same emissions at ground level.

Water vapor is a potent and short-lived greenhouse gas, present mostly at lower altitudes. Introducing H2O into the normally dry air of the upper troposphere and lower stratosphere create the condensation trails we've all seen and possibly the formation of cirrus clouds. Since cirrus clouds don't typically form in the upper atmosphere, there remains uncertainty as to the impact on climate, though studies suggest that these high-altitude clouds have an insulating effect, trapping heat.

In the report Aviation and the Global Atmospherethe Intergovernmental Panel on Climate Change (IPCC) determined that aviation emissions have about two times the impact as ground-based emissions.

How does business square the reality of aviation emissions and sustainable business?

Industry focus on efficiency, sustainability

For air charter companies, business jet operators, airlines and manufacturers, building more efficiency into the aviation system doesn't necessarily stem from a desire to be “environmentally correct,” but more a matter of economic “life or death,” writes Daniel Gross in SlateNonetheless, many industry leaders have understood for some time that what's good for the environment is good for the bottom line.

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.

Roger Bowman, corporate sustainability process manager for Gulfstream Aerospace, speaks of a "multi-pronged approach" toward sustainability.

"In addition to reducing our carbon footprint, we're focused on improving aircraft efficiencies," Bowman says. "For example, the Gulfstream G650ER flies farther faster than any other business jet in the world, burns less fuel for the same mission and, as a result, has a reduced carbon footprint and produces fewer emissions, such as nitrous oxide. We continue to invest in research that will ensure our aircraft are fuel‐efficient and quiet to further lessen their environmental impact."

The Savannah, Georgia-based company has invested in new silver LEED-certified manufacturing facilities for their G650, G600 and G500 series of jets. The manufacturing process for these airplanes utilizes "bonded skin technologies and an increased use of machined parts and composites in strategic areas as part of our advanced airframe materials construction" to increase efficiency, says Bowman.

Gulfstream employs a sustainability manager in its production operation to conserve resources, institute recycling and promote green practices.

"Our production processes benefit from those company‐wide environmental initiatives, which range from energy‐saving strategies, such as turning lights and equipment off when not in use and setting indoor temperatures appropriately to double‐sided printing and office recycling programs," Bowman says.
Bombardier (Learjet), Cessna and Boeing (which also makes business jets) all have sustainability initiatives in their manufacturing process and the products they make.

Other efficiency improvements include advanced avionics packages and streamlined air traffic management.

"In 2008, Gulfstream promoted environmentally conscious flying through sharing best practices with our operators. This information provided practical steps for the pilot to use in order to reduce fuel burn and hence, CO2. It covers all aspects of flight (taxi, climb, cruise, descent and landing). It also provides tips for planning a flight that would reduce fuel burn, such as fuel loading as well as simple ways to reduce unnecessary payload."

As the FAA rolls out the NextGen air traffic control system, more efficient traffic handling reduces fuel consumption both on the ground and in flight. For UPS, this translates into a nightly fuel savings of 7,761 gallons of fuel for arrivals at their hub Louisville, Kentucky.

In Seattle, the Greener Skies Over Seattle Initiative is implementing proceeders such as Optimized Descent Profiles (essentially a glide at idle power-down to the runway threshold), Area Navigation (RNAV), GPS-guided arrivals and the even more precise Required Navigation Performance (RNP) approach. RNAV and RNP require properly equipped airplanes.

Gulfstream and other business aviation manufacturers are actively innovating to make use of these new technologies. "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."

"Gulfstream is actively involved in industry developments and plans to develop new systems in line with FAA’s NextGen, Europe’s SESAR, India’s GAGAN, etc. As an example, Continuous Descent Trajectory is the ability to begin the descent to an airport hundreds of miles away at idle power without the standard level‐offs of today. Using advanced on‐board navigation systems and displays, the aircraft can reach the airport with significantly less fuel burned."

Focus on fuel

There is, in fact, such a thing as a solar powered airplane. It flies low and slow and carries one person. The energy density required to push a big airplane and its cargo requires high-density fuels capable of delivering an immense amount of energy. So, a practical solar or electric-powered airplane is a long way off, if even possible. For the foreseeable future, energy-dense liquid fuel (Jet A for turbojets and Avgas for turboprops) is the only means of getting humans and their cargo off the ground.

Despite more efficient airframes and design “... the continued growth of the industry is outstripping the ability of current technology to compensate for the environmental problems. Renewable energy sources may be able to offset some of these environmental trends …” states the research paper The Potential for Renewable Energy Sources in AviationResearch and development into alternative and sustainable (not necessarily the same thing) aviation fuels is a major focus, both in government and industry, and business aviation is often at the forefront of innovation.

"Alternative fuels can help the business‐aviation industry achieve the goals outlined by NBAA and other associations,” says Gulfstream's Bowman, "which include achieving carbon‐neutral growth by 2020; achieving fuel efficiencies of 2 percent annually through 2050; and reducing carbon‐dioxide emissions by 50 percent by 2050 (2005 is the baseline). Alternative fuels are a key element to the industry achieving these goals."

"In 2011, a Gulfstream G450 became the first business jet to cross the Atlantic using biofuels,” Bowman adds. "The Honeywell‐operated aircraft flew from North America to Europe using a 50/50 blend of Honeywell Green Jet Fuel and petroleum‐based jet fuel. In 2012, we flew our full fleet of demonstration aircraft to the 65th Annual National Business Aviation Association Meeting & Convention on advanced biofuels."

Several options for alternative fuels include synthetic Fischer-Tropsch kerosene produced from biomass, biodiesel and hydrogen. Flying in a hydrogen-fueled airplane is at best many decades away, since it would require modified airframes and jet engines. The best prospect for alternative aviation fuel is "drop in" fuels. These alternative fuels can be used, or dropped in, with current infrastructure. Honeywell's Green Jet Fuel converts a wide range of non-edible feedstock algae or camelina into jet fuel that "meets or exceeds all critical jet fuel specification" and offers a 65 to 80 percent reduction in greenhouse gas emissions.

Research into fuel alternatives is an industry-wide effort. As with all biofuels, one of the big challenges is ramping production to commercial scale.

International Civil Aviation Organization Climate Action Plan

At the 37th Session of the International Civil Aviation Organization (ICAO) in 2010, adopted a "benchmark" objective for voluntary action from its 190 member states for developing action plans to reduce carbon emissions. At the United Nations Climate Summit in New York City in September, the ICAO further clarified specific goals addressing climate change:

  • Improving fleet fuel efficiency by 1.5 percent per year through 2020.

  • Stabilizing net emissions from 2020 through carbon-neutral growth, subject to concerted industry and government initiatives.

  • Reducing net aviation carbon emissions 50 percent by 2050, relative to 2005 levels.

ICAO outlines three main pathways for achieving these goals:

  1. Development of new, more efficient aircraft technology and sustainable alternative fuels.

  2. Promotion and deployment of operational improvements to reduce CO2 emissions from aircraft already in service.

  3. Making better use of infrastructure, particularly air traffic management.

As we've seen, business aviation companies such as Gulfstream and others already incorporate these pathways in the research, design, development and production of their products.
"We are involved with the ICAO through our support of manufacturing organizations such as the National Business Aviation Association, the General Aviation Manufacturers Association and the International Business Aviation Council," Bowman says.

ICAO also provides a Green Meetings Calculator, a Fuel Savings Estimation Tool and other environmental toolkits for assessing consumption and emissions.


In an article published by the Energy Collective, entitled Could Rising Aviation Emissions be Good for the Environment?, Adam Whitmore writes that "the only realistic option for capping net [aviation] emissions at 2020 levels over the next few decades is likely to be the use of offsets."

In particular, Whitmore points out that carbon offsets can't be a permanent solution to aviation emissions, but in the short- to medium-term, a high-quality program could increase market demand for offsets. This could in turn increase funding for programs such as REDD+, providing immediate benefit from reduction of deforestation.  These offsets should incorporate additionality, permanence and provide adequate governance, he says. Whitmore also suggests buffers be built into an aviation emissions offset program to account for leakage and to "realize an explicit goal of net benefits." For instance, 1.5 tons of carbon offsets equals 1 ton of aviation emissions. These seem to me a minimum, if we are to add in a buffer and account for the total climate-forcing impact from aviation emissions.

There are several programs aimed specifically for private and business aviation, including Terrapass and Flexjet, Bombrardier's fractional jet ownership program, in partnership with ClimateCare. Five percent of the purchase price of offsets from the Terrapass program goes directly to fund new aviation technology. This is important: As Whitmore states in his article, offsets can't be a final solution. An unintended consequence of offset programs is that they can trigger a "rebound away from meaningful mitigation and towards the development of further high-carbon infrastructures," writes Kevin Anderson in the journal Nature

Offsets must not be considered a final solution nor pull focus from innovation and absolute mitigation of greenhouse gas emissions -- from airplanes or any other source. The best greenhouse gas offset is the one not emitted in the first place.

The conundrum of aviation

It’s a safe bet that most people reading this article have flown at least once in their lives, probably a lot more than that. Many likely use alternatives to scheduled commercial airlines. Aviation is the backbone of a modern global economy and increasingly a part of our lives. Even those who advocate never flying are likely dependent on aviation in some way, whether it be shipping, opening the letter dropped in your mailbox from a relative thousands of miles away, or any number of common, daily occurrences we take for granted. Most of us depend on business aviation without even realizing it.

This is not to say there isn't excess. Seeing Kim and Kanye jet all over the world is hardly giving private aviation a more responsible environmental image than did those CEOs back in 2008. But making closer the day when a rich celebrity or CEO flies their private jet on sustainable alternative fuel, powering engines that sip that fuel and emit few greenhouse gases, is the challenge the industry must now address. It's a big challenge, but let's consider all the challenges the aviation industry has met and overcome to get where it is today. One hundred years ago, we had barely taken to the skies in powered flight. Today business depends on it, and the miracle of flight is available to anyone reading this post.

As comedian Louis C.K. put it: "You got to fly! It’s amazing! Everybody on every plane should just constantly be going ‘Oh my God! Wow!’ You’re flying! You’re sitting in a chair, in the sky!'”

Image credit: Jerome_K/Flickr

Thomas Schueneman headshotThomas Schueneman

Tom is the founder, editor, and publisher of GlobalWarmingisReal.com and the TDS Environmental Media Network. He has been a contributor for Triple Pundit since 2007. Tom has also written for Slate, Earth911, the Pepsico Foundation, Cleantechnia, Planetsave, and many other sustainability-focused publications. He is a member of the Society of Environmental Journalists

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