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.
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).