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Decarbonization & Greening.
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The fall in aircraft CO2 emissions in 2020 was concurrent with a 60% drop in global air traffic.
IEA research shows that after increasing rapidly over the past two decades, CO2 emissions from aviation fell by one-third from the 2019 level in the wake of the pandemic to just over 600 Mt in 2020 – the lowest level since 1997. Despite this unprecedented collapse, passenger numbers and cargo volumes are set to rise in the coming decades.
In the future, the counterbalance to CO2 growth will come from a range of operational, technical and behavioural solutions.
These will be required to cut emissions from 2025 onwards, to reduce them to just over 780 Mt of CO2 by 2030 and around 470 Mt CO2 by 2040 in line with the Net Zero Emissions pathway. Near- to medium-term priorities include implementing fiscal and regulatory measures to promote efficiency; managing the investment risks for scaling up sustainable fuels; and developing alternatives to jet kerosene, such as battery-electric and hydrogen-powered aircraft. (IEA)
Sustainable Aviation Fuel (SAF) is more expensive so it is fair to say that it cannot replace the efficiency and energy output of Jet-A. Sustainable aviation fuel is chemically like traditional fossil fuels used for jets and can be produced from sustainable feedstock. In environmental terms, air transportation is facing a particularly challenging decade. The industry must remove the pollution generated by aircraft and develop more efficient aviation technology to help offset greenhouse gas emissions (GHG). Jet-A weakness is pollution! Air transportation generates between 1.5% and 4% of the GHGs that humans generate in overheating Earth's biosphere. Some observers may see that as a manageable problem, but when viewed as a component of the transport sector of the global economy, aviation is responsible for ~ 21% of that sector's GHG emissions. Air transportation faces a unique dilemma. It is one of the most polluting industries because of its dependence on fossil fuel, in the form of Jet-A kerosene, and no technology exists that can be substituted for the gas turbine engines that emit CO2e (equivalent) as the aircraft flies at an altitude of around 12,000 meters. A single long-haul aircraft can pollute, flying New York to Frankfurt, emits approximately one ton of CO2. Unsatisfactory though this is, a traveler cannot travel by road, trains, or passenger ship to a destination on the other side of the Ocean. In terms of domestic flights CO2e emissions per passenger, per kilometer, 255 grams of pollutant material is generated. In this market that substitute forms of travel can be utilized, cost effectively, and at the same time reduce GHGs. Decarbonization is essential for a healthy industry. The path to decarbonization is necessary for a healthy aviation industry and if the travelling public is to continue air travel products and services. “Aviation is a highly concentrated industry, meaning that a small number of manufacturers, airlines, and airports have a large share of their respective markets. This concentration of market share and influence means decisions can be made quickly and have a global impact,” Shell states. Although current costs of SAF are prohibitively high (especially for exclusive use), many companies such as Twelve are developing SAFs with funding from major industry figures like the US Air Force, Shell, and BP. The technology only continues to grow in its potential, and the technical and commercial benefits of sustainable aviation fuels show that fuel efficiency and environmental responsibility are not mutually exclusive! The lack of progress on the engine technology and sustainable fuel fronts is such that there is a heavy focus on the transportation sector as a bad actor and a particular focus on aircraft because they are ever present in the sky. Pressure on aircraft manufacturers, suppliers, airlines, airport and lessors is mounting to the point where civil society groups (CSG) and institutional investors that support them, are demanding that the current emissions standards be raised significantly, be enshrined in law and be backed up by strenuous regulation. For now, the industry is relying on the standards set out in the ICAO Corsica scheme to make the case that aviation is living up to its commitments on climate change, based on the standard of technology that existed in the 1990s.
Decarbonization approach is global.
Conventions, standards & recommended practices.The UN, with the agreement of "the international community adopted two major Conventions and one scheme to deal with subjects: 1. Convention on International Civil Aviation. Otherwise know as the Chicago Convention, was signed in 1944. 2. United Nations Framework Convention on Climate Change (UNFCCC) treaty was signed in 1992 at the Rio Summit. The climate emissions action being dealt with, through the UNFCCC treaty, deals only with domestic emissions, leaving international emissions unaddressed. Domestic aviation emissions fall under the purview of the UNFCCC, a UN agency, and are covered by the Paris Agreement.3. CORSIA. Another UN agency, the International Civil Aviation Organization (ICAO) was given the mandaye to address international CO2 emissions. The UN member states of ICAO met in 2016 and adopted a "global" market-based measure for aviation green house gas emissions. They launched the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). It is an interim measure to help aviation meet the goal of carbon-neutral growth covering the period 2020 to 2035, when CORSIA ends. The scheme is managed by ICAO, with the support of the aviation industry. The rules are implemented at a national level. The scheme aims to mitigate around 165M tonnes of CO2 emissions per year, using three polution reduction measures: a. technology, b. sustainable aviation fuel, c. operations and infrastructure options.
EPA Clean Air Act.
In 2016, under section 231 of the Clean Air Act, EPA found that:
1. Concentrations of six well mixed GHGs in the atmosphere—CO2, methane, nitrous oxide (N2O), hydrofluorocarbons, per- fluorocarbons, and sulfur hexafluoride—endanger the public health and welfare of current and future generations, and
2. GHGs emitted from certain classes of engines used in certain aircraft are contributing to that endangering air pollution.
Airplane engines emit two of the six well-mixed GHGs, CO2 and N2O. Accordingly, EPA is adopting GHG standards that match the ICAO fuel efficiency-based standards, which control the GHGs emitted by airplane engines, CO2 and N2O. Aircraft GHG Emissions. The U.S. transportation sector is a significant contributor to total U.S. anthropogenic GHG emissions. Aircraft remained the single largest GHG-emitting transportation source not yet subject to GHG standards in the U.S. U.S. aircraft covered by the rule (this includes all domestic flights and international flights originating in the U.S.) emit: • 10 percent of GHG emissions from the transportation sec