GREENING of Aviation: Altitude, Innovation and Capture

CORSIA, altitude, hydrogen engine and capture
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CO emissions goal stretching

Research- greener altitudes for contrails

Technology- greener hydrogen engines more feasible

Capture- system to remove Carbon from air

Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) has set some challenging goals for global aviation reduction of carbon emissions.  The pandemic has retarded some of the work, but the virus has reduced demand/operations.

Three different aspects of this effort to further green aviation bear highlighting:

  • Adjusting altitude to reduce contrails
  • New Technologies to minimize CO emissions.
  • Creating technology that will CAPTURE CO

Below, an article about Contrails, then a series of reports about efforts to bring innovation to greener flights and finally a report of United’s investment in capture:

  1. Altitude and contrail reduction research

contrail crystals

New Data on Aviation’s Impact on Global Climate

There’s some good news and bad news for the airline industry in a study released last month that I think is the most comprehensiveReason Foundation scientific assessment to date of the various atmospheric impacts of aviation on climate change. The study was released by Manchester Metropolitan University and led by its climate scientist David Lee.

Manchester Metropolitan and David Leeand One headline finding is that aviation’s climate-relevant emissions—CO2, nitrogen oxides, and contrails—nearly doubled between 2000 and 2018. But aviation’s percentage contribution has remained about the same, at 3.5 percent. That’s because many other sources have also increased significantly during that nearly two-decade period of global economic growth. The study also confirmed that the largest aviation contribution is the formation of contrails, as exhaust particles and water vapor lead to the formation of the ice crystals of which contrails are composed. But while contrails are still the largest component, they cause only about half as much warming impact as previously thought.


CO2 remains the second-largest contributor, responsible for about 60 percent as much as contrails. The smallest of the three contributors is nitrogen oxides, with about 30 percent of the impact of contrails.

The good news, according to some experts, is that fixing contrails is the easiest of the three to achieve. As I reported in the February issue of this newsletter, the Center for Air Transportation Research at George Mason University (Lance Sherry and Terrence GMU Center for Transportation ResearchThompson) released a detailed study explaining contrail formation and analyzing the cost and potential impact of a number of mitigation measures. By far the most cost-effective would be to change the altitudes of the 15 percent of (U.S.) flights that fly in conditions that lead to the formation of contrails. They estimate that a 2,000-foot increase in cruise altitude for those flights would reduce contrail impact by 62 percent, while a 4,000-foot increase would reduce it by 92 percent. This would require better meteorological data in flight planning, but its cost in terms of fuel burn and flight time would be small.

The findings on contrails are also important for the potential use of hydrogen as a replacement aircraft fuel. Yes, its combustion would produce no CO2 and no nitrogen oxides—but lots of water vapor ready to turn into ice crystals—i.e., contrails. But the same remedy—slightly higher altitudes—would apply to hydrogen-fueled planes, as well.


contrail crystals


  1. GREEN Technology Developments

BA hydrogen test aircraft

British Airways Wants Hydrogen Flight Revolution To Come Sooner

“…In a press release published earlier today, British Airways announced its intention to “speed up the switch to hydrogen-powered passenger aircraft.” It will do so through a partnership with ZeroAvia, a “leading innovator in decarbonizing commercial aviation.” Through remote work, it plans to explore the concept of utilizing zero-emission hydrogen fuel with industry experts.

The partnership will come under the wider umbrella of the International Airlines Group’s (IAG) ‘Hangar 51’ accelerator program. This scheme looks to assist smaller start-ups worldwide. It does so by giving them the opportunity to test and develop their projects on a larger scale within IAG’s operations

[An aviation startup has completed what it calls the world’s first hydrogen fuel cell-powered passenger aircraft flight ]


MTU Empowered by Growing Hydrogen Propulsion Consensus

MTU Dornier 228 hydrogen


“…The 19-seat aircraft, which has already been procured, will have one of its two Honeywell TPE331 turboprop engines replaced by a 500-kW electric motor, powered by electricity produced by hydrogen fuel cells. Under a partnership announced in early August, MTU will provide the propulsion system while DLR—the government-backed Deutsches Zentrum fur Luft und Raumfahrt agency—will be responsible for systems integration and certification. The partners will use the project, which has funding from the Bavarian state government, to validate MTU’s powertrain architecture.

At the same time, MTU says that it also views direct combustion of liquid hydrogen in gas turbine engines as a potentially faster means of adopting the alternative fuel. According to Dr. Stefan Weber, senior v-p of technology and engineering advanced programs, the required changes to the combustion chambers of engines could be made within “a few years” to allow for relatively easy modification of existing aircraft.”

Hydrogen fuel could revolutionize airlines. Here’s how that could look

Airbus 3 concept planes

“…Last month, European aircraft maker Airbus announced it would evaluate three concept planes, each of which would be primarily powered by hydrogen. The goal is to figure out an aircraft design and manufacturing process so the hydrogen plane could potentially enter commercial service by 2035.

“Alternative fuels are the key to unlocking air transportation emissions,” said Megan Ryerson, the University of Pennsylvania’s UPS chair of transportation and an associate professor of city and regional planning and electrical and systems engineering. “Without them, we either have to stop flying or make drastic cuts in other sectors.”

There’s a lot researchers like about hydrogen. For one, it’s incredibly energy dense — more so than jet fuel, and much more than current battery technology. It’s also plentiful and burns cleanly, producing no carbon dioxide or carbon monoxide.

“Hydrogen is an amazing fuel,” said Gozdem Kilaz, an associate professor at Purdue University’s school of engineering technology. “It is theoretically a wonderful fuel option.”

  1. Another Technological Approach


United to invest in ‘direct air capture’ as it makes 2050 carbon-neutral pledge


Chicago-based United will initially make a “multi-million investment” in that process, called “direct air capture and sequestration”.

The investment will go to a company called 1PointFive, which is jointly owned by a subsidiary of Occidental Petroleum and private equity firm Rusheen Capital Management.

The funds will help 1PointFive “build the world’s largest direct-air capture and sequestration plant”, says Kirby. “We are committed to be 100% green by 2050.”

The facility will be in the USA and will use direct air capture technology licensed from Canadian company Carbon Engineering.

Carbon Engineering has also been working with jet developer Aerion Supersonic to develop synthetic fuel from CO2 derived via direct air capture.

United CEO Kirby

“The only way we can truly make a dent in carbon… is through direct-air capture and sequestration,” Kirby says. “It is the only solution that is real, permanent and scalable.”






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