Sylvie Willis
The combustion of jet fuel is a significant contributor to greenhouse gas emissions from aviation, with CO2 being the largest component, accounting for about 70% of the exhaust. The amount of CO2 emitted per kg of jet fuel combusted is approximately 3.16 kg, according to the ICAO in 2017. This figure includes the emissions during the production, transport, and refinery processes of kerosene jet fuel. The impact of aviation emissions on the climate is more complex than just the radiative forcing effect of CO2, and current regulatory approaches do not fully capture the magnitude of this impact. Additionally, jet fuel consumption produces water vapour, which constitutes about 30% of the exhaust, and various gases and particulates that have warming or cooling effects on the climate.
| Characteristics | Values |
|---|---|
| CO2 emitted per kg of jet fuel combusted | 3.16 kg |
| Additional CO2 emitted per kg of jet fuel during production | 0.5 kg |
| Total CO2 emitted per kg of jet fuel | 3.66 kg |
| Percentage of aircraft emissions that occur above 3,000 feet | 90% |
| Percentage of aircraft emissions that occur during taxi, takeoff, initial climb, and landing | 10% |
| Average additional CO2 per economy-class passenger on a round-trip flight from Frankfurt to New York | 870 kg |
| Average CO2 emitted by a European per year | 9 tons |
| Average additional CO2 emitted by a European on a round-trip flight from Frankfurt to New York | 1 ton |
| Potential mitigation strategy | Use of sustainable biofuels blended with kerosene jet fuel |
Explore related products
What You'll Learn
CO2 emissions during jet fuel combustion
The combustion of jet fuel (kerosene) emits CO2, with approximately 3.16 kg of CO2 released for every kilogram of jet fuel combusted. This ratio remains constant regardless of the flight phase. The production of kerosene also contributes to emissions, adding approximately 0.5 kg of CO2 per kg of jet fuel. As such, a round-trip flight between Frankfurt and New York emits about 570 tonnes of CO2, resulting in an average of 870 kg of CO2 per economy-class passenger.
The impact of jet fuel combustion on the climate is significant, with aviation emissions having a greater effect than the simple radiative forcing impact of CO2. The warming effect of CO2 is amplified when emitted at high altitudes, with studies suggesting that high-altitude emissions could increase radiative forcing by an amount equivalent to 1.7 to 4.3 tonnes of CO2 per passenger. This amplification is due to the extended lifetime of CO2 in the atmosphere, where it can remain for thousands of years, contributing to its potency as a greenhouse gas.
In addition to CO2, jet fuel consumption also produces water vapour, which constitutes about 30% of the exhaust. However, water vapour has a minimal direct warming impact due to its short atmospheric lifespan as part of the water cycle. Other emissions from jet fuel combustion include soot, sulfates, and particulates, which contribute to contrail formation. These contrails can lead to the formation of cirrus clouds, which absorb solar radiation and further enhance the warming effect.
Regulatory approaches have addressed aviation emissions as if they were equivalent to ground-level CO2 emissions, without considering the knock-on effects of high-altitude combustion. To mitigate the environmental impact, sustainable biofuels blended with kerosene jet fuel have been introduced, offering a lower lifecycle greenhouse gas assessment and reduced soot, water vapour, and sulfate content. Additionally, routing changes to avoid contrail-producing conditions have been proposed, although they may lead to increased traffic and extended flight durations, resulting in higher CO2 emissions.
The Cost of 'How Much Is
You may want to see also
Explore related products
CO2's warming impact
The combustion of jet fuel releases CO2, which has a warming impact on the planet. For every kilogram of jet fuel burned, 3.16 kg of CO2 is emitted. In addition to the direct emissions from combustion, the production of jet fuel, including transport and refinery processes, adds approximately 0.5 kg of CO2 per kg of fuel. This means that a round-trip flight from Frankfurt to New York, burning about 156,500 kg of jet fuel, results in about 570 tonnes of CO2 emissions, or an average of 870 kg of CO2 per economy-class passenger.
The warming impact of CO2 is significant and has far-reaching consequences for our planet. Firstly, CO2 is a greenhouse gas that remains in the atmosphere for a long time. While about half of the emissions are absorbed by oceans and forests within 30 years, another 30% is removed within a few hundred years, and the remaining 20% can persist in the atmosphere for thousands of years. This long residence time allows CO2 to accumulate, leading to a gradual increase in its atmospheric concentration.
The rising levels of atmospheric CO2 have a direct impact on global temperatures. CO2 molecules in the atmosphere absorb heat, creating a heat-trapping blanket that prevents a portion of the Earth's energy from escaping into space. This phenomenon is known as the greenhouse effect, and it is responsible for the gradual warming of our planet. The increase in atmospheric CO2 concentrations over the last 60 years has been 100-200 times faster than natural increases during the end of the last ice age. This rapid rise is primarily driven by human activities, such as the combustion of fossil fuels, including jet fuel.
The warming impact of CO2 emissions from jet fuel is not limited to the direct release of CO2. Aviation emissions have a more significant impact on climate change than just the radiative forcing effect of CO2. Emitting CO2 at high altitudes, such as during air travel, amplifies the warming effect. Additionally, contrails formed under certain conditions can lead to the formation of cirrus clouds, which absorb solar radiation and contribute further to warming. These knock-on effects are not fully captured by current regulatory systems, which often treat aviation emissions as equivalent to ground-level CO2 emissions.
The consequences of the warming impact of CO2 are severe and wide-ranging. The increase in global temperatures due to CO2 and other greenhouse gases has led to climate change, causing more frequent and intense extreme weather events, rising sea levels, and disruptions to ecosystems and weather patterns. To mitigate these impacts, it is crucial to reduce CO2 emissions, transition to sustainable energy sources, and develop methods to remove CO2 from the atmosphere.
Unleashing the Power of Top Fuel Dragsters
You may want to see also
Explore related products
CO2 emissions during kerosene production
The combustion of kerosene jet fuel releases CO2, with approximately 3.16 kg of CO2 emitted per kilogram of fuel burned. However, the CO2 emissions associated with kerosene jet fuel extend beyond combustion. The production, transport, and refinery processes involved in kerosene manufacturing contribute an additional 0.5 kg of CO2 per kg of jet fuel. This means that the total CO2 emissions associated with kerosene jet fuel are approximately 3.66 kg of CO2 per kg of fuel.
The production of kerosene jet fuel, like any fuel, contributes to CO2 emissions. The specific amount of CO2 emitted during kerosene production depends on various factors, including the energy sources and processes used. For example, the efficiency of electricity generation can significantly impact CO2 emissions. Lower efficiency in electricity generation results in higher carbon dioxide emissions. This relationship between power plant efficiency and CO2 emissions is evident when comparing different fuel sources and power plant types.
In the case of natural gas combined cycle power plants, higher efficiency leads to lower carbon dioxide emissions. Replacing lignite-fired electricity with natural gas can result in significant reductions in direct carbon dioxide emissions, as seen in Germany. However, to fully understand the environmental impact, it is essential to consider not only the direct emissions but also the upstream chain emissions and their contribution to the greenhouse effect.
Additionally, the production of biofuels, such as biodiesel, can result in varying levels of CO2 emissions depending on the energy sources used during synthesis. For instance, biodiesel production via Fischer-Tropsch synthesis can have low CO2 emissions if processed with energy sources that have low carbon dioxide emissions themselves. On the other hand, if the processing energy has high CO2 emissions, the overall carbon footprint of biodiesel production will be higher.
The calculation of CO2 emissions during kerosene production is complex and involves considering direct emissions, greenhouse gas equivalents, and leakage losses. Sustainable wood, for instance, may be considered a source of indirect emissions due to factors such as harvesting, transport, incomplete combustion, and reduced CO2 storage capacity of forests. While burning wood results in the instantaneous recycling of carbon, the overall climate impact of biofuels depends on the time frame for the renewal of organic material and the specific biomass resources utilized.
Fuel Pump Power: How Much Battery Juice?
You may want to see also
Explore related products
Altitude's effect on emissions
The combustion of jet fuel emits 3.16 kg of CO2 per kg of fuel burned. This ratio stays the same regardless of the phase of the flight. However, the emission of CO2 is not the only concern when it comes to jet fuel. Other byproducts, such as water vapor, nitrogen oxides, soot, and sulfates, also contribute to the environmental impact of aviation.
The altitude of an aircraft has a significant effect on emissions. Most aircraft emissions occur above 3,000 feet, and the climate impact of these emissions is greater than the radiative forcing effect of CO2 alone. This is because the warming effect of CO2 is amplified at high altitudes. Some studies suggest that high-altitude emissions could increase radiative forcing by an amount equivalent to 1.7 to 4.3 tonnes of CO2 per passenger. However, these figures are uncertain and may vary.
The optimum cruising altitude for modern jetliners is between 35,000 and 42,000 feet, which offers the best balance between air density, lift, drag, and engine performance. Flying at higher altitudes results in thinner air, which reduces drag and improves fuel efficiency. Additionally, as the aircraft consumes fuel during the flight, its weight decreases, and flying at higher altitudes helps compensate for this weight loss by reducing lift.
However, flying at higher altitudes also has its drawbacks. As altitude increases, air density decreases, resulting in reduced lift and engine thrust. Therefore, flying at excessively high altitudes would require the aircraft to fly faster to maintain sufficient lift, which could offset the fuel efficiency gains. Additionally, higher altitudes may have lower oxygen levels, impacting engine performance, and colder temperatures, which could affect engine efficiency.
To mitigate the environmental impact of emissions at high altitudes, several strategies have been proposed. One approach is to use sustainable biofuels blended with kerosene jet fuel, which can reduce the lifecycle greenhouse gas assessment and decrease soot content, water vapor, and sulfates in the exhaust. Another strategy is to reduce the sulfur content of kerosene jet fuel and modify engine designs to decrease exhaust particulates. Additionally, flight planning and altitude adjustments can be made to avoid conditions that promote the formation of contrails, which contribute to the warming effect at high altitudes.
Soaring Gas Prices: How High Will They Go?
You may want to see also
Explore related products
Strategies to reduce emissions
According to the ICAO, 3.16 kg of CO2 are emitted per kilogram of jet fuel combusted. This figure includes emissions during the production of kerosene and accounts for transport and refinery processes, adding approximately 0.5 kg of CO2 per kg of jet fuel.
Sustainable Biofuels
One strategy to reduce emissions is to blend sustainable biofuels with kerosene jet fuel. This approach has already begun to enter the commercial aviation market and can reduce the formation of contrail-induced cirrus clouds, a major climate impact of aviation. Biofuel blends also decrease soot content, water vapour, and sulfates in the exhaust, thereby reducing contrail formation.
Engine Design Changes
Engine design modifications can also help to reduce emissions. For instance, reducing the sulfur content of kerosene jet fuel can lower exhaust particulate emissions.
Flight Planning and Altitude Changes
Altering flight paths and altitudes can help aircraft avoid ambient conditions that contribute to contrail formation. However, it is important to consider that routing changes may lead to increased traffic and extended flight durations, which could, in turn, raise CO2 emissions.
Cross-Industry Coalitions
The U.S. Department of Energy's Bioenergy Technologies Office is working with fuel refiners and aviation companies to demonstrate Sustainable Aviation Fuel (SAF) technologies at a large scale. This collaboration helps to lower production costs and accelerate the integration of SAF into the aviation industry, thereby reducing emissions.
Applied Science and "Drop-In" Biofuels
The National Renewable Energy Laboratory (NREL) and its partners are employing applied science to develop "drop-in" biofuels that are chemically similar to conventional jet fuel. These SAFs can be seamlessly integrated into existing pipelines, storage tanks, and engines without requiring costly delays or infrastructure changes.
The 787 Dreamliner's Fuel Capacity: How Much Can It Hold?
You may want to see also
Frequently asked questions
3.16 kg of CO2 is emitted per kg of jet fuel combusted.
Jet fuel, also known as kerosene jet fuel, is a fossil fuel that is combusted during aircraft flights to produce CO2.
CO2 has a direct warming effect on the climate when emitted from jet fuel and other fossil fuel combustion sources. The warming impact of CO2 is greater at high altitudes where approximately 90% of aircraft emissions occur.
A transatlantic round-trip economy flight, such as from Frankfurt to New York, adds about 1 metric ton of CO2 to an individual's climate footprint. This is equivalent to the average annual emissions of a European.
