Comparison of NOx Emissions from Different Turbofan Power Plants Flying @ 41,000 ft - by Pedro Baldó

Comparison of NOx Emissions from Different Turbofan Power Plants For Super Jumbo, Ultra Long, HH, XR, LR, Mid-Sized Super Mid-Sized & Executive Liners Flying Above at 41,000 ft.

by Pedro Baldó Part II of Report

In 2018, aircraft were responsible for about 3 percent of total U.S. carbon dioxide emissions and nearly 9 percent of greenhouse gas emissions from the U.S. transportation sector.

Commercial air travel accounted for most of the aircraft carbon dioxide emissions, with military and private aviation making up for the rest.

Why should NOx emissions matter to us ??

Excess nitrogen in the atmosphere can produce pollutants such as ammonia and ozone, which can impair our ability to breathe, limit visibility and alter plant growth. When excess nitrogen comes back to earth from the atmosphere, it can harm the health of forests, soils and waterways.

Deposition Levels of NOx It is estimated that in 1860, 34 Tg N/ yr of Nitrogen was emitted as NOx and NH3 and then deposited to the Earth’s surface as NOy and NHx; in 1995, it had increased to 100 Tg N/ yr ; by 2050, it is projected to be 200 Tg N /yr.

N deposition to ecosystems in the absence of human influence is generally ≤ ½ kg N /(ha).(yr).

1 Tg N /yr = 1,000,000 tonnes (m) Nitrogen/yr.

There are now large regions of the world where average N deposition rates exceed 10 kg N per (ha).(yr), greater than an order of magnitude increase compared with natural rates.

By 2050, this may double, with some regions reaching 50 kg N /(ha).(yr), and landscape-level inputs may be much larger, especially for forest ecosystems.

Critical loads for the open ocean have not been calculated, but recent studies conclude that the increasing amounts of atmospheric anthropogenic Nitrogen entering the ocean could foster the growth of annual new marine biological production by ~ 3% and increase the emission of N2O to the atm. by at least ~ 1.6 Tg N yr–1. Too much nitrogen and phosphorus in the water causes algae to grow exponentially, producing excess CH4 ,

faster than ecosystems can handle. Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive. Large growths of algae, called algal blooms (seen thriving out of control in Lake Maracaibo) severely reduce and eliminate the oxygen in the water, decreasing the pH level.

This acidic water, leads to illnesses in the fish populations that inhabit that whole ecosystem, eventually bringing them to their inevitable demise.

The loss of one or two species, at first, might not be apparent to us, but this does begin to tear down on the fundamental fabric of nature to the point there´s irreversible damage.

Starting to see some analogy on the bigger scale here ?

Emissions of aircraft NOx were calculated to be approximately 0.7 Tg N / yr in the REACT4C aviation emissions scenario (2006). Emissions scenarios indicate that these emissions may increase by 2050, over the range 0.8-5 Tg N /yr.

The resultant increase in NOx concentrations, and the effects on the composition of the atmosphere, in particular with respect to ozone formation in the upper troposphere and lower stratosphere, are examined.

Although aviation contributes only a small proportion (about 3%) of the total global NOx the models show that aviation contributes a large fraction to the concentrations of NOx in the upper troposphere, in particular north of 30 degrees north. The model when applied to the latitude band of 40 to 50 degrees north indicated an increase of nitrogen oxide in the upper troposphere on the order of 30 % to 40% due to aircraft emissions.

Under idle conditions aircraft emissions have particularly high NO2 fractions. The mean f-NO2 for these aircraft emissions is 0.14. At the aircraft engine exit, hot combustion gases mix with ambient air to quickly cool the gas stream. In the exhaust plume, as emissions continue to cool, some molecules undergo chemical reactions producing other molecules that can also condense into particles. VOCs in the presence of sunlight, NOx can form ozone.

However, nitrogen dioxide (NO2) from the plume can convert to nitric acid (HNO3) vapor that interacts with ammonia in the atmosphere and forms ammonium nitrate (NH4NO3) particles and other oxidation reactions involving gaseous hydrocarbons from the plume, yielding condensable organic compounds that form organic aerosol particles. Ammonia, is the main alkaline component in the atmosphere.

Although the rate-of-growth over the last decade in the mass of aviation NOx emissions has exceeded on-road (i.e., cars and trucks) NOx emissions growth, the quantity of emissions of other transport modes still far exceeds those from aviation.

Turbojet and Turbofan engines Engine technology has continuously evolved over the last 70 years, and reduction in fuel burn has always been a driving force behind this progress. More fuel efficient engine cycles, often made possible through the use of new materials, has led to increasing pressures and temperature within the combustor.

Since this tends to increase the emissions of nitrogen oxides (NOX), the control of these emissions through the combustor design is a significant challenge. The ICAO regulatory limits for engine NOX emissions has been gradually tightened over time, and are usually referred to by the corresponding CAEP meeting number (CAEP/2, CAEP/4, CAEP/6 and CAEP/8).

The engine NOX standard, and the new aircraft CO2 standard, contribute in defining the design space for new products so as to address both air quality and climate change issues.

The table in the next page shows the top picks for NOx emissions (gr./kN) for private jets and executive liners, as regards the highest turbine inlet temperatures for each of the manufacturers.

Figure 2.5 illustrates certified NOX emissions data of aircraft engine models above 89 kN thrust in relation to the ICAO CAEP NOX limits. The regulatory NOX limits are defined as the mass (Dp) of NOX emitted during the Landing and Take- Off (LTO) test cycle and divided by the thrust of the engine (F00). The limit also depends on the overall pressure ratio (OPR) of the engine. The current ICAO technology goals for NOX are also shown.

Figure 2.5 Continued implementation of latest NOx mitigation technology within certified engines

https://www.easa.europa.eu/eaer/figurestables/continued-implementation-latest-noxmitigation-technology-within-certified-engines Interactive graph: Hover the mouse over the series to visualize their values / coordinates. Click on a series name in the legend to unselect/select it. You can also scroll forward or backward to zoom in/out and click and move your mouse to pan to the desired area.

These goals, which were agreed upon in 2007, represent the expected performance of expected ‘leading edge’ technology in 2016 (mid-term) and 2026 (long term). Each point in the graph represents EASA certified data for an engine model, and the different colors provide insight into the trend over time.

The dataset represents engine models typ. fitted to single-aisle aircraft (A320, B737) and larger aircraft (e.g. A350, B777, A380).

Reducing Aviation Emissions in the Future FAA has made significant progress addressing environmental concerns through the strategy and programs it has created under the Five Pillar Environmental Approach. New engine designs and technologies, like those developed in the CLEEN program, are improving fuel efficiency further, while simultaneously reducing noise, NOx and PM emissions.

New aircraft designs are taking advantage of advanced computer models to improve operating performance and fuel efficiency, reducing all pollutants at the same time.

New air traffic control (ATC) technologies and operating practices are reducing emissions by reducing fuel consumption.

And alternative jet fuels are being developed that will cut the impact of aviation on climate change and air quality significantly.

Aviation has safely and progressively improved its environmental performance over the last 70 years. This commitment to operating in balance with the environment and in support of beneficial environmental mitigation practices are forcefully stated in the FAA’s Aviation Environmental and Energy Policy Statement, as further advanced by the Aviation Greenhouse Gas Emissions Reduction Plan (AGGERP).

Fuel economy, which is one strong indicator of environmental performance, has consistently improved. Aircraft engines have gotten more efficient and been designed with environmental performance in mind.

Regulatory frameworks have developed to constrain emissions growth from many aviation sources. Improvements to the efficient operation of the complex aviation network have had a positive effect on the environment.

New fuels are being developed, or existing ones being improved to reduce harmful emissions as well as aviation’s impact on climate change. Much of this progress is a direct result of the research conducted in the programs planned and managed by FAA’s Office of Environment and Energy.

FAA, together with EPA and NASA, is committed to ensuring aviation emissions do not pose human health risks,

degrade the global climate, or restrain aviation’s mobility and economic benefits enjoyed by society sustainably.

FAA has the strategic framework in place for planning and implementing an emissions research roadmap for continuing to mitigate the environmental impacts of aviation emissions. This includes continuing to improve understanding of the role of aviation emissions on health impacts on the

Earth´s surface as well as climate change.

FAA is working with industry and other stakeholders to advance the performance of the national and international aviation system as well as to improve individual system components. Within ICAO, the FAA continues to work on a comprehensive basket of solutions to mitigate aviation emissions impacts while simultaneously working to improve energy efficiency.

Conclusions Though reducing N creation and its Unwanted impacts will be challenging, it is both possible and of critical importance.

With respect to aircraft engines, the CAA requires EPA to consult with the FAA and provides the FAA with the authority to enforce EPA’s aircraft engine emissions standards through its certification regulations.

FAA is responsible for ensuring these regulations do not pose conflicts with safety and other aircraft operational requirements.

For example there are more than 60 standards that apply to aircraft engine design, materials of construction, durability, instrumentation and control, and safety, among others. These are in addition to the Fuel Venting and Exhaust Emission Rqmts for Turbine Engine Powered Airplanes (RTEPA).

The RTEPA specify compliance with EPA’s aircraft exhaust emission standards.

FAA’s Next Generation Air Transportation System (Next Gen) together with the Office of Environment and Energy (AEE) will establish the programs, systems, and policies needed for safer, more responsive and efficient air transport.

This will weigh heavily on the tailing down of the emissions from private jets and turbofans.