The United Nations regards achieving global net zero emissions by the middle of this century as the most urgent mission of all mankind at present. In 20 18, a campaign called "flying shame" was launched in Sweden, which quickly swept across Europe. More and more people are beginning to choose more environmentally friendly ways to travel. The general trend is broad. If the aviation industry cannot innovate and transform, it will be eliminated and downgraded, and a new round of technological revolution and global competition has begun.
Aviation decarbonization is imperative
The report of the United Nations Intergovernmental Panel on Climate Change (IPCC) points out that it is very important to achieve the goal of zero carbon dioxide emission by 2050 in order to control global warming within 65,438+0.5 degrees Celsius compared with the pre-industrial level. Since the signing of the 20 15 Paris Agreement, it is the general trend to achieve carbon neutrality as soon as possible and achieve net zero emissions in major industries in the middle of this century. As an important component and support of global economic activities, the aviation industry must actively change and take the initiative.
Since 2007, the long-sighted aviation industry has begun to explore industry-wide emission reduction. Many international organizations and civil aviation-related organizations have made corresponding plans, the most important of which is the International Aviation Carbon Offset and Emission Reduction Plan (CORSIA) adopted by the International Civil Aviation Organization (ICAO) in 20 16, thus forming the first global market mechanism for industry emission reduction, and the aviation industry has thus become the first industry in the world to implement global carbon-neutral growth measures by the government. According to the plan, the carbon emissions of the global aviation industry will be reduced by 50% by 2050 compared with 2005.
At the same time, the European Union and the United States have successively set the goal of achieving carbon neutrality in 2050. In July, 20021,the European Commission proposed the "Adaptation 55" regulation to ensure carbon neutrality in 2050. The United States followed closely, and released the long-term strategy of zero net emissions in 2050 on June 5438+065438+1October of that year, and announced the time node and technical path to achieve carbon neutrality in 2050. As the two "engines" of the aviation industry, the United States and Europe have greatly advanced the emission reduction targets of the aviation industry: it is clear that net zero emissions will be achieved by 2050.
202 1 10 The Air Transport Action Group (ATAG), representing the global air transport industry, urged ICAO member countries to support the adoption of long-term emission reduction targets at the 2022 ICAO Assembly 4 10.
At the 26th United Nations Climate Change Conference (COP26) held in 20021,1654381October, 23 countries including Britain, the United States and France formed the International Aviation Climate Ambition Alliance and signed the International Aviation Climate Declaration, aiming at strengthening intergovernmental cooperation and making ambitions for international aviation emissions. In particular, it is suggested to support the adoption of ambitious long-term goals by ICAO and urge ICAO to make specific commitments to achieve net zero emissions by 2050. At the same time, the International Air Transport Association (IATA), whose members include 290 airlines, expressed its support for the 2050 net zero carbon emission flight plan.
In February this year, under the auspices of France, which holds the rotating presidency of the European Union, 42 developed countries signed the Toulouse Declaration on Sustainable Aviation Development and Decarbonization in Toulouse, Europe, calling on the world to take measures to achieve the goal of decarbonization of the aviation industry by 2050 in order to curb global warming. Europe and the United States and other countries hope to trigger a chain reaction through this non-binding initiative, so as to promote the global air transport decarbonization commitment to be adopted at the 4 1 ICAO General Assembly. The initiative has also been supported by Airbus, KLM, Dassault and other 146 industry companies. It is emphasized that international cooperation under the framework of ICAO is essential to ensure global fair competition.
Salvatore Sciacchitano, President of ICAO Council, attended the event. He stressed that although the epidemic situation and its impact are still going on, governments and aviation industries of various countries have made ambitious decisions and taken practical actions to promote the decarbonization of international aviation.
All of the above points to the upcoming ICAO meeting in September this year. The organization is in full swing to carry out research and consultation on the long-term global goal (LTAG) of carbon dioxide emission reduction in international aviation. From the end of March to the beginning of April, the organization will hold a global aviation dialogue on this, and the progress of relevant consultations will be submitted to the LTAG high-level meeting and finally voted at the September meeting. It will undoubtedly be an ambitious goal to decarbonize the aviation industry in 2050. No matter what commitments and restrictions ICAO finally makes, the decarbonization of the aviation industry is in sight.
Aviation technology is brewing great changes.
Although the aviation industry is not a super carbon emitter, it is definitely a "difficult household" for carbon emission reduction. The main reason is that long-distance flights are also heavily dependent on fossil fuels. To realize decarbonization of aviation, whether it can make a breakthrough in technology is the key.
The French newspaper Echo believes that the current aviation industry is about to usher in the third aviation revolution. The first aviation revolution was the successful test flight of the Wright brothers' first plane in the early 20th century. The second revolution was in the 1950s, and the advent of turbofan engine announced that the aviation industry had entered a golden age. So what is the third aviation revolution?
Dr. Frank Anton, head of power flight technology of Siemens in Germany, gave his answer without hesitation: electricity. Anton pointed out: "Electric propulsion technology is the development direction of aviation industry, otherwise the aviation industry will have no future." The Siemens team has initially completed the design, development and flight test of the hybrid propulsion system. In 20 15, Siemens introduced the electric aircraft motor, which weighed only 50kg, but its power was as high as 260kw, realizing the first flight of the world's first 250kw electric aircraft. In the future, through the continuous optimization of power system and the progress of battery technology, Siemens hopes to develop a 100 hybrid aviation device.
For French counterparts, the answer to this question is also one word: hydrogen. The French Civil Aviation Research Council (Corac) published a research report on the technical route of decarbonization in air transport in June+10 this year. The report believes that the decarbonization of the industry needs to be realized by continuously increasing the proportion of hydrogen-powered aircraft in the future. In its planned road map, France can launch a new generation of short-haul aircraft in 2030, achieve carbon neutrality by reducing fuel consumption and biofuels, launch short-haul hydrogen-powered aircraft in 2035 and launch medium-range hydrogen-powered aircraft in 2045. By 2050, hydrogen technology can contribute 29% to all carbon neutrality in the aviation industry. In another more radical European joint research report, it is pointed out that replacing fuel with hydrogen can reduce the impact of air transportation on climate by 50% to 70%.
Electricity and hydrogen are two main research and development routes of propulsion technology at present.
According to the report of Montaigne Institute in France, considering the energy density of batteries and fuel cells, the application of pure electric propulsion will mainly be small aircraft. For large aircraft, hybrid electric propulsion can be used as a transitional technology to realize complete electrification. Hybrid electric propulsion can be combined by connecting a conventional engine and electric propulsion in series or in parallel. This concept has been used in the automobile industry for a long time.
According to the current technical prospect, it is difficult for all-electric aircraft with more than 100 seats to be put into use before 2050. /kloc-the business of small aircraft with less than 0/9 seats is growing, but at present it only accounts for less than 1% of the total global aviation emissions. For medium and long-range large aircraft, it seems that the only realistic technical options are hydrogen and sustainable aviation fuel (SAF). Hydrogen propulsion here is different from fuel cells that rely on hydrogen to generate electricity. Hydrogen-propelled aircraft burn hydrogen as engine fuel.
At present, major countries in Europe and America regard hydrogen propulsion as the best candidate for aircraft decarbonization, and it is also one of the main technical solutions that can be realized in 2035. The advantage of hydrogen fuel is that the combustion temperature is high, which can improve the thermal efficiency of the engine and the carbon emission is zero. From the perspective of engine manufacturers, it is not difficult to replace fuel with hydrogen, mainly to solve the problem of high temperature resistance of materials caused by hydrogen combustion. Even if adjustment is needed, 90% of the engines may remain unchanged. The main difficulty in selecting hydrogen is the storage problem on the plane. Under the same on-board capacity, the weight of hydrogen fuel is one-third of that of traditional fuel, but its volume is four times that of fuel, which requires the adjustment of aircraft structure. Moreover, liquid hydrogen needs to be stored at a low temperature of-253 degrees Celsius, and the material of the storage tank requires high heat insulation, shock resistance, load bearing and sealing, so it is necessary to develop a liquid hydrogen storage tank that can withstand the thermal cycle and pressure cycle under the application requirements of aircraft.
According to the forecast of Montaigne Institute in France, in order to achieve the goal of decarbonization in 2050, regional flights (mainly 100 small aircraft) that currently account for about 3% and 4% of global aviation emissions can be decarbonized based on hybrid electric propulsion and hydrogen fuel cells; Short and medium-haul flights (mainly 100 250-seat medium-sized passenger aircraft) accounting for about 67% of aviation emissions can mainly rely on hydrogen propulsion technology; Long-haul flights (mainly large passenger aircraft with more than 250 seats), which account for about 30% of aviation emissions, also need to rely on sustainable aviation fuel.
In addition to propulsion technology, aviation decarbonization needs to make progress in improving aerodynamics, optimizing engine performance, and increasing digitalization.
Aviation giants have entered the market one after another.
In September 2020, Airbus launched the ZEROe zero-emission commercial aircraft project, and announced three concept aircraft with mixed hydrogen energy, using three concept aircraft, namely turboprop, wing-body fusion and turbofan, and using hydrogen as fuel. The prototype is tentatively scheduled for flight test in 2025 and put into use in 2035.
In February this year, 20 months after the announcement of the hydrogen-powered aircraft project, Airbus announced a strong alliance with CFM, a flat-share joint venture company of General Motors and Safran Group. The two sides decided to start the hydrogen-powered aircraft demonstration project around 2025. The project aims to conduct ground and flight tests on hydrogen-fueled engines and prepare for the launch of the first zero-emission aircraft in 2035. The demonstration project will use the A380 test aircraft as a flight test platform, equipped with liquid hydrogen tanks prepared by Airbus factories in France and Germany. Starting from 2026, Airbus will test the hydrogen-fueled engine during the A380 cruise.
In the United States, Pratt & Whitney was selected by the Advanced Energy Research Program of the US Department of Energy in February this year to develop new and efficient hydrogen fuel propulsion technology for commercial aviation.
Pratt & Whitney's "Hydrogen Steam Injection and Intermittent Cooling Turbine Engine" project will use liquid hydrogen fuel. By recovering water vapor, the condensation wake of the aircraft will be greatly reduced, thus achieving zero greenhouse gas emission flight and reducing 80% nitrogen oxide emissions. The semi-closed system architecture adopted in this project will have higher thermal efficiency than fuel cells, and the total operating cost may be further reduced than that using "drip" sustainable aviation fuel. This is the first direct cooperation between Pratt & Whitney and the American Advanced Energy Research Project to support the aviation industry's strategic goal of achieving zero carbon dioxide emissions from aircraft in 2050.
According to the French "Echo" report, Boeing still seems to have reservations about the feasibility of realizing hydrogen-powered aircraft in 2035, and Boeing is more inclined to give priority to traditional aircraft running on alternative fuels.
In Russia, Rostec announced a plan to develop hydrogen-powered engines for aviation and ground applications in July 20021. Yuri Shmottin, chief designer of United Engine Company of Russia, said: "In order to reduce the carbon footprint of the aviation industry, the use of hydrogen fuel is one of the most promising development areas. We are considering two main technologies: direct combustion of hydrogen fuel in an improved gas turbine and the use of hydrogen fuel cells to generate electricity. "
For China, opportunities and challenges coexist.
According to an article in le figaro, many international aviation observers believe that the competition of zero-carbon aircraft is a historic opportunity for China to finally enter the commercial aviation market. Nicholas Bogran and Pascal Fabres, managing directors of global consulting firm AlixPartners, believe: "Zero-carbon aircraft involves the development of new technologies, and long-term investment in China certainly has a license to play." As another expert summed up: "Everyone is on the same starting line."
Dr Ye Weiming, President of China Air France Association, said in an interview: "In the research and development of hydrogen-powered aircraft, all countries are at the same starting line. This is an important opportunity for China. " Ye Weiming said that China's aviation industry and energy industry must seize the historical opportunity of the third aviation revolution and start as soon as possible. China is still in the catch-up stage in the field of classic aero-engines, so it is suggested that China aviation manufacturing should leapfrog to new energy technologies as soon as possible and make bold transformation.
Yi Ding, vice president of China Air France Association and Airbus R&D engineer, said: "The Airbus zero-carbon aircraft has clearly defined the technical route of hydrogen energy. For China's civil aircraft industry, new energy aircraft structures and engines such as hydrogen fuel may be opportunities for overtaking in corners, but the accumulation of deposits is still a long-term challenge. The essence of the new track of zero-carbon aircraft is aviation manufacturing. We must strive for steady progress on the basis of the China model task and strive to narrow the gap in design concepts, manufacturing processes and test methods. "
For more than half a century, Airbus and Boeing have kept ahead through technological progress, but under the change, the former "Big Mac" cannot guarantee to keep ahead in the future. Regarding whether to choose hydrogen energy, Airbus and Boeing have parted ways, one is full of ambition and the other is conservative. If the aviation industry wants to realize decarbonization in less than 30 years, it must rely on scientific and technological breakthroughs that subvert the tradition. Whether the aviation industry can be "hydrogen" in the future depends on bold innovation, courage and foresight. (This article is taken from cstnet)
Hydrogen fuel and transportation
As a green, efficient and sustainable secondary energy, hydrogen has been used as fuel for a long time.
When the world's first internal combustion engine was put into use, it used hydrogen instead of gasoline or diesel. 1804, the French and Swiss inventor Isaac de Rivaz, after successfully designing several cars powered by steam, began to try to use fuel with deflagration characteristics instead of steam. His first experiment was to study the basic principle of pushing the piston to move after the fuel in the engine cylinder exploded and expanded. At that time, he used hydrogen-oxygen mixed ignition to drive the internal combustion engine, and the experiment was initially successful. 1807, he installed the prototype engine on a four-wheeled carriage and drove the carriage for a certain distance, which made the carriage win the honor of "the world's first car driven by an internal combustion engine".
In the 20th century, automobile companies, universities, inventors and enthusiasts were further testing the feasibility of hydrogen-driven internal combustion engines. 1970, the inventor Paul Digges applied for a patent to improve the gas-fired internal combustion engine. His design allows gasoline engines to use hydrogen. Today, hydrogen-fueled engines have been proved to be capable of powering all kinds of vehicles, from cars to buses.
For decades, the aerospace industry has been using liquid hydrogen as a propellant for hydrogen-oxygen rocket engines to provide fuel for space exploration.
The research on hydrogen as aircraft fuel also has a long history. As early as 1957, the National Aviation Advisory Committee (NACA) used hydrogen as fuel and let Martin B-57 bomber fly for 20 minutes. 1988, the world's first experimental commercial aircraft fueled by liquid hydrogen was launched. This Tu- 155 * * developed by the Soviet Union has been tested about 100 times. Today, more than 30 years later, the aviation industry once again turned its attention to hydrogen-fueled commercial aircraft.