It’s impossible to turn the clock back on the industrial and technological gains of the last couple of hundred years, but at the same time, it’s increasingly clear that we need to prevent further damage to the planet. For individuals, flying is one of the most polluting activities they can undertake – an average short-haul flight produces 133g of CO2 emissions per passenger, compared with 104g for bus passengers and 43g if you take a private car with 3 other occupants1. The non-CO2 pollutants emitted by airplanes are even worse, affecting the balance of gases and pollutants in the atmosphere2, and causing a long-term drop in ozone and methane. Planes emit water vapor as contrails, which trap infrared light rays to produce a warming effect that’s up to three times as significant as carbon dioxide.3 To be fair, the air industry’s total contribution to global carbon emissions is relatively low, around 2.5%4, and the non-CO2 emission make up 3.5% of global warming5. In contrast, a recent report from the EU found that road transport contributes 19.35% of the region’s total greenhouse gas emissions6. Yet air travel remains high on the list for reducing pollution. As public awareness rises around climate change, consumers are increasingly choosing airlines based on their carbon footprint. Governments committed to reducing carbon emissions are also concerned about the contributions of the air industry to overall emissions levels. Additionally, while the air industry’s overall contribution may be low, it’s growing quickly. Emissions from international aviation rose by 128% between 1990 and 2017, and by 2050, plane emissions are predicted to be 7 to 20 times higher than 1990 levels, despite improvements in fuel consumption during that time7. While expansion has been slowed by COVID-19, the sector is still predicted to grow by 4% per year over the next 2 decades8.
Despite a few outliers like the Green Party in Germany, which is suggesting banning short-haul flights9, few people expect to drastically reduce air travel. Granted, COVID-19 slashed the number of flights taking place worldwide, but we’re already seeing them pick up again as vaccines roll out. Analysts predict that passenger travel will return to 2019 levels by 2024, and cargo flights by mid-2021.10 While improving fuel consumption and engine efficiency plays a role in lowering aviation pollution, many politicians and industry thought leaders hope that hydrogen fuel will save the day, enabling more environmentally-friendly air travel at a reasonable price.
A number of clean fuel alternatives suggested for ground transport aren’t practical for airplanes., but hydrogen fuel cell planes are showing promise. It’s estimated that hydrogen-powered planes could reduce the climate impact of a flight by 50-75%, compared with a 30-60% change for synthetic fuels11. Hydrogen fuel has three times more energy per unit of mass than conventional jet fuel12, and over 100 times more than lithium-ion batteries13. Hydrogen is available in abundance across the planet, primarily in a compound with oxygen. To produce hydrogen fuel, energy companies use electrolysis to harvest the hydrogen molecules, then store them in pressurized containers until transferring them into a fuel cell which allows the energy to be released as electricity. When the electrolysis is powered by renewable energy sources, the fuel is termed “green hydrogen.”
The past few years have seen the cost of renewable energy drop while supply has risen, making green hydrogen more affordable and more accessible. Since 2015, the cost of electrolyzers has fallen by 50%, and it’s predicted to decrease by another 40-50% by 2030, while renewable energy capacity is expected to increase tenfold by 205014. By 2030, it’s predicted that the EU will have electrolyzer capacity of 40 Giga-Watts 15 and that the cost of producing hydrogen fuel will have fallen by 30%16. Combined with penalties for fossil fuel use and tax breaks for green fuels, which are either in place or on the horizon in many countries, green hydrogen may soon be able to compete with jet fuel in terms of price. Against this background, a number of companies are exploring the possibilities of hydrogen-powered planes. One of the leaders in this field is Airbus, which unveiled 3 new airliner designs in September 2020 called ZEROe concept aircraft, all powered by hydrogen. The ZEROe planes offer three different approaches to overcoming the challenges of hydrogen flight. The Turboprop model has 100 seats, uses modified hydrogen gas turbines to power the turboprop engine, and has a range of up to 1,000 nautical miles (nm). The larger Turbofan plane has a narrow body and turbofan engines, with space for up to 200 passengers and a range of 2,000 nm, while the biggest and most radical new design, the Blended Wing Body (BWB) has a wider than average fuselage that allows for a cabin alongside multiple fuel storage and distribution options. The BWB can carry up to 200 passengers for flights of around 2,000nm.17 Airbus say they’re exploring which is the best option with a view to making a decision by 2024 and introducing the new model by 203518.
As is common in disruptive verticals, most innovation is coming from newer startups. Paul Eremenko, former Airbus chief technology officer, started Universal Hydrogen to actualize his innovative concept of delivering refillable hydrogen capsules, which he compares to Nespresso pods, directly from fuel production facilities to the aircraft. Hydrogen fuel cell distribution expert Plug Power partnered with Universal Hydrogen, investing $1 million in the startup. Plug Power agreed to initially supply 500 tons of hydrogen daily from five US distribution points by 2024.19
ZeroAvia, a green aviation startup, is also pushing innovation. In September 2020, the company announced the first successful hydrogen fuel cell powered flight of a commercial-grade aircraft, flying a 6-seater Piper M-class for 20 minutes around the company’s R&D unit in the UK. Its next goal is a 250-mile flight from an airfield in Orkney, which is equivalent to busy routes like LA to San Francisco or London to Edinburgh.20 AeroDelft, a team of students at Delft University in the Netherlands, is another innovator. The group just unveiled a prototype called Phoenix PT, a crew-less plane powered by liquid hydrogen with an expected range of 500km and 7 hours flying time. They plan to hold a test flight in the summer of 2021, and are working on the two-passenger Phoenix FS, which they hope to have ready for test flights in summer 2022.21 In Germany, a partnership between MTU Aero Engines and the DLR Aerospace Research Center is converting a Dornier 228 regional airliner to run on proprietary hydrogen fuel cells. They intend to begin ground testing subsystems by the end of June 2021.22 Industry opinion isn’t universally supportive, however. Some companies are hedging their bets. In December 2020, Rolls Royce launched a new MTU series 500 Ultrafan gas engine, which will initially be offered for natural gas and biogas, but that can be converted to use gaseous hydrogen23. Boeing has poured cold water on hydrogen optimism, with commercial vice-president and general manager of product development Michael Sinnett saying ““I don’t think it’s something that’s right around the corner,” even while admitting that hydrogen power has “unique promise”24.
Naysayers point to the fact that hydrogen fuel needs to be stored in pressurized tanks to compress the gas, or else kept at extremely low temperatures to preserve it in liquid form, and these tanks are complex to build and/or heavy. Although hydrogen is energy-dense, it’s still only a quarter of the density of jet fuel, so hydrogen planes would need storage tanks that are four times as large as they are today for the same journey, making planes heavier. Airport authorities are also reluctant to implement a new infrastructure to store and deliver hydrogen fuel. Some raise safety concerns about the flammability of hydrogen fuel, but studies have shown that it’s no more flammable than traditional jet fuel25.
But while long-range flight is still a long way in the future, it may not be long before hydrogen power rolls out for short flights. The EU’s Fuel Cells and Hydrogen Joint Undertaking (FCH) predicts that hydrogen aircraft could enter service by 2035 for short range aircraft, with an extra cost per person of under $20 and 50-90% lower climate impact26. Analysts at McKinsey predict that operational costs for hydrogen-powered commuter and regional flights would increase by just $5-10 per passenger, costing around $60 per abated ton of CO2. For short range aircraft, costs would rise by 20-30% per passenger, and cost per abated ton of CO2 begins at $70.27 Dr. Bart Biebuyck, executive director of the Fuel Cells and Hydrogen Joint Undertaking, says that “By 2035, [hydrogen flight] should be possible for a short-range flight plane. That means on European soil; you could connect all the big cities in Europe using hydrogen-powered planes. By 2050, the ambitious scenario is that 40% of the (European aviation) fleet would be powered by hydrogen.”28 When it comes to adopting hydrogen flight, the biggest challenge is not aircraft but infrastructure. “It’s not just a question of putting hydrogen-based airplanes and getting them to work, we need the infrastructure on the ground to support everything,” said David Gleave, aviation safety investigator and researcher at Loughborough University, UK29. The McKinsey report acknowledges that refueling infrastructure will require significant investment and coordination, covering transport of hydrogen fuel safely to the airports, fuel truck networks to deliver fuel to the aircraft, new handling and safety regulations, and a reorganization of supply chains that could include other hydrogen-using industries. It urges the industry to take bold steps to make it happen.30
As part of its support for hydrogen aircraft, Airbus is working together with airports and airlines to ensure that the infrastructure is put into place. One suggestion is to repurpose existing pipelines, currently used for natural gas, to transport hydrogen fuel. Some airport hubs could develop on-site hydrogen production, especially those situated close to a renewable energy source.31 ZeroAvia is also developing a Hydrogen Airport Refuelling Ecosystem (HARE) as a model of a hydrogen airport ecosystem32.
It’s clear that more research, development, and investment is needed before hydrogen planes are a commercial reality, but as the public and political pressure grows, companies are advancing innovation. Meanwhile we see that hydrogen fuel has yet another use case, now for powering air travel. Advances in hydrogen-powered flight are likely to strengthen the hydrogen market further, driving more enthusiasm for investment in hydrogen stocks.
1 “Climate change: Should you fly, drive or take the train?” August 24, 2019 https://www.bbc.com/news/science-environment-49349566
2 “Climate change and flying: what share of global CO2 emissions come from aviation?” October 22, 2020 https://ourworldindata.org/co2-emissions-from-aviation
3 “Fact Sheet | The Growth in Greenhouse Gas Emissions from Commercial Aviation” October 17, 2019 https://www.eesi.org/papers/view/fact-sheet-the-growth-in-greenhouse-gas-emissions-from-commercial-aviation
4“Climate change and flying: what share of global CO2 emissions come from aviation?” October 22, 2020 https://ourworldindata.org/co2-emissions-from-aviation
5“Climate change and flying: what share of global CO2 emissions come from aviation?” October 22, 2020 https://ourworldindata.org/co2-emissions-from-aviation
6 “Emissions from planes and ships: facts and figures (infographic)” April 28, 2021 https://www.europarl.europa.eu/news/en/headlines/society/20191129STO67756/emissions-from-planes-and-ships-facts-and-figures-infographic
7“Emissions from planes and ships: facts and figures (infographic)” April 28, 2021 https://www.europarl.europa.eu/news/en/headlines/society/20191129STO67756/emissions-from-planes-and-ships-facts-and-figures-infographic
8 “Airline Industry Set for COVID Comeback, But It Will Be a Slow Climb” February 12, 2021 https://www.kiplinger.com/personal-finance/spending/leisure/travel/602254/airline-industry-set-for-covid-comeback-but-it-will
9 “German chancellor candidates target cheap flights over climate concerns” May 17, 2021 https://www.cleanenergywire.org/news/german-chancellor-candidates-target-cheap-flights-over-climate-concerns
10 “When will aviation recover in full?” January 12, 2021 https://www.aerotime.aero/26845-aviation-recovery-forecast-analysis
11 “Hydrogen-powered aviation” May 2020 https://www.euractiv.com/wp-content/uploads/sites/2/2020/06/20200507_Hydrogen-Powered-Aviation-report_FINAL-web-ID-8706035.pdf
12 “Hydrogen in aviation: how close is it?” October 8, 2020 https://www.airbus.com/newsroom/stories/hydrogen-aviation-understanding-challenges-to-widespread-adoption.html
13 “A hybrid engine concept for multi-fuel blended wing body” September 30, 2014 https://www.emerald.com/insight/content/doi/10.1108/AEAT-04-2014-0054/full/html
14 “Thematic Investing: The Special 1 – Hydrogen primer,” Bank of America Securities, Global Research, 23 September 2020, p.5.
16 “Hydrogen in aviation: how close is it?” October 8, 2020 https://www.airbus.com/newsroom/stories/hydrogen-aviation-understanding-challenges-to-widespread-adoption.html
18 “The Case For Hydrogen Powered Aircraft Gains Momentum” May 3, 2021 https://www.ainonline.com/aviation-news/aerospace/2021-05-03/case-hydrogen-powered-aircraft-gains-momentum
19 “The Case For Hydrogen Powered Aircraft Gains Momentum” May 3, 2021 https://www.ainonline.com/aviation-news/aerospace/2021-05-03/case-hydrogen-powered-aircraft-gains-momentum
22 “Aircraft Engine Makers Mostly Agnostic on Hydrogen” May 3, 2021 https://www.ainonline.com/aviation-news/aerospace/2021-05-03/aircraft-engine-makers-mostly-agnostic-hydrogen
236 “Rolls-Royce unveils hydrogen-ready gas engine” December 11, 2020 https://www.powerengineeringint.com/decentralized-energy/cogeneration-chp/rolls-royce-unveils-hydrogen-ready-gas-engine/
24 “Hydrogen-powered airliners unlikely in near term: Boeing exec” September 23, 2020 https://www.flightglobal.com/airframers/hydrogen-powered-airliners-unlikely-in-near-term-boeing-exec/140273.article
25 “Hydrogen powered aircraft : The future of air transport” July 2013 https://ui.adsabs.harvard.edu/abs/2013PrAeS..60…45K/abstract
26 “Hydrogen-powered aviation” May 2020 https://www.fch.europa.eu/publications/hydrogen-powered-aviation
27 “Hydrogen-powered aviation” May 2020 https://www.euractiv.com/wp-content/uploads/sites/2/2020/06/20200507_Hydrogen-Powered-Aviation-report_FINAL-web-ID-8706035.pdf “Sustainable synthetic carbon based fuels for transport” September 2019
28 “Quiet and green: Why hydrogen planes could be the future of aviation” July 9, 2020 https://www.technology.org/2020/07/09/quiet-and-green-why-hydrogen-planes-could-be-the-future-of-aviation/
29 “Is Hydrogen The Future In Aviation?” November 1, 2020 https://simpleflying.com/hydrogen-aviation-future/
30 “Hydrogen-powered aviation” May 2020 https://www.euractiv.com/wp-content/uploads/sites/2/2020/06/20200507_Hydrogen-Powered-Aviation-report_FINAL-web-ID-8706035.pdf
31 “Hydrogen in aviation: how close is it?” October 8, 2020 https://www.airbus.com/newsroom/stories/hydrogen-aviation-understanding-challenges-to-widespread-adoption.html