Saving fuel is in

Sustainability in aviation: an overview

11.2016 | Text: Silke Hansen

It is not as if the industry has only just woken up to the issue. Aviation can already point to huge pro­gress in its environ­mental per­formance. Over the past 50 years, CO2 emissions have been reduced by 70 per­cent per passen­ger kilo­meter. In 2015, the average fuel con­sump­tion of German air­lines was only 3.6 liters per 100 passen­ger kilo­meter across all air­craft types and routes, according to cal­cu­la­tions by the German Aviation Association (BDL). However, because the transport sector continues to grow, there are numerous ini­tia­tives designed to make the in­creasing aviation traffic more en­vi­ron­men­tal­ly friendly.

From generation to generation, air­planes and air­craft engines have become in­creas­ingly efficient. Less kero­sene consumption means less CO2. There is a direct re­la­tion­ship between fuel con­sump­tion and emis­si­ons of this green­house gas. Through nu­mer­ous measures, the industry is working on cur­tailing kero­sene con­sump­tion and there­fore green­house gas emissions.

Growth without additional emissions

Today, aviation has committed itself to am­bi­tious goals, both at European and inter­national levels—and in­ci­den­tal­ly, it is the only trans­port sector to do so. In several stages, green­house gases are to be reduced by 75 per­cent per passen­ger kilo­meter by 2050 compared to the year 2000 according to the European aviation research organi­zation ACARE’s Strategic Research and Inno­vation Agenda (SRIA). The Inter­national Air Transport Association (IATA) is pursuing the goal of carbon neutral growth from 2020.

The International Civil Aviation Organization ICAO, the UN’s avia­tion agency, is also targeting air­craft CO2 emissions and wants to put an inter­nationally valid CO2 stand­ard in place. According to this stand­ard, new air­craft from 2020 on should observe the specified CO2 limits, and models that are already in pro­duction should meet the limits by 2023. From 2028, no air­craft that does not comply with the stand­ard should be allowed to take off. “Although avia­tion is currently re­spon­sible for less than two per­cent of annual CO2 emis­sions, we have to struc­ture the expected doubling of world­wide passen­ger traf­fic from 2030 in a re­spon­sible and sus­tain­able way,” warns Presi­dent of the ICAO Council, Dr. Olumuyiwa Benard Aliu. In October 2016, ICAO initiated a global climate agreement designed to sys­tem­ati­cal­ly compensate for growth-related CO2 emissions resulting from air travel from 2020.

Aviation does not affect the climate through CO2 emissions alone, even if their impact is the strongest. The com­bus­tion of kerosene produces air­borne pollu­tants such as nitric oxides, for which ICAO thresholds have long been in place. Another con­tribu­tor to global warming is the creation of contrails and cirrus clouds at high altitudes. Mini­mizing this problem is a job for air traffic manage­ment experts, who should develop new flight routes that mean air­craft can fly lower.

Inside MTU Corporate Responsibility

How sustainable is an individual organization? What can it con­trib­ute to climate pro­tection? What is par­ticu­lar­ly important to it? Answers to these questions are provided by sustain­ability reports, which many big companies now compile. This includes MTU, which publishes annual infor­mation about its sustain­ability objectives and standards as defined by the inter­nationally valid guide­lines of the Global Reporting Initiative (GRI). In this way, the indi­vidual reports can be compared against each other. For the year 2017, this elective measure will become mandatory—at least in Europe. Then a new law will come into force that requires listed companies with more than 500 em­ployees to publish infor­mation on sustain­ability topics. A major focus for MTU is the Clean Air Engine (Claire) agenda, which seeks to reduce the CO2 emissions of air­craft engines by 40 per­cent by 2050 (see also page 45). But that is not all by any means: MTU also shows respon­sibility toward employees, suppliers and society.

Alternative fuels

Sustainable fuels are an alternative to kerosene. However, the require­ments of these fuels as regards energy density, safety and operating char­ac­ter­is­tics are much higher than for road transport. At the moment, several second-generation bio­fuels are author­ized for standard flight operations. These so-called drop-in fuels possess the same char­ac­ter­is­tics as kerosene and can be used for all air­craft and air­ports. World­wide, aviation requires almost 500,000 tons of kerosene every day. The large-scale pro­duction of bio­fuels must not nega­tively impact food pro­duction or bio­diversity. For this reason, special­ists are carrying out research into synthetic fuels manu­factured through process engi­neer­ing so­lu­tions such as using solar energy in the desert to pro­duce avia­tion fuel out of water and CO2. Not all methods are cost-effective yet. According to the Aviation Initiative for Renewable Energy in Germany, alter­native aviation fuels cannot currently be produced at com­peti­tive costs.

As a long-term approach, the industry is inten­sively dis­cussing another possibility: electric flying. “In our estimation, current tech­nol­ogy is still several decades away from an electric-powered A320,” says Dr. Jörg Sieber, who is respon­sible for inno­vation manage­ment at MTU Aero Engines. Electric flying would require much more powerful batteries and electric motors than are avail­able today. “Short-range regional air­craft are con­ceiv­able perhaps in 30 years’ time. For medium- and long-haul flights, suit­able battery concepts are currently lacking.” In view of this, MTU has chosen to invest in hybrid systems com­prising a gas turbine with a generator and electri­cally powered fans. But how sustain­able is electric flying? No oil is burned up in the air­craft’s engine of course, avoiding the emission of harmful exhaust gases, but the elec­tri­city powering the air­craft has to be produced, and must not come from the burning of fossil fuels.

Facts & Figures: Sustainability in the aviation industry

Worldwide, the aviation industry is working for a greener future: over 400 organi­zations in 65 coun­tries have initiated projects designed to reduce green­house gases—including air­craft manu­facturers, air­lines, engine specialists and air­port operators.

Here is a small selection:

First “bioport” in continuous operation: Oslo Air­port mixes biofuels into its fuel hydrant system. Amsterdam and Brisbane plan to follow suit.

Innovative aircraft tractor: Lufthansa’s new TaxiBot brings air­craft from gate to runway with engines stopped.

Green revolution: the Geared Turbofan developed by Pratt & Whitney and MTU reduces CO2 emissions by 16 per­cent in the first generation alone.

New technologies: as part of the EU research programs LEMCOTEC, E-BREAK and ENOVAL, the engine industry is developing tech­nol­ogies for new engines designed to reduce fuel con­sump­tion by up to 26 percent from 2025 (compared to the year 2000).


Silke Hansen, writes for AEROREPORT as a freelance journalist. For over ten years, she has covered the world of aviation focusing on tech­nol­ogy, inno­vation and the market. Corporate re­spon­sibil­ity reporting is another of her specialty areas.

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