A hydrogen-powered aircraft is an

aeroplane An airplane (American English), or aeroplane (Commonwealth English), informally plane, is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes come in a vari ...

that uses

hydrogen fuel The hydrogen economy is an umbrella term for the roles hydrogen can play alongside low-carbon electricity to reduce emissions of greenhouse gases. The aim is to reduce emissions where cheaper and more energy-efficient clean solutions are not avail ...

as a power source.

Hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

can either be burned in a

jet engine A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...

or another kind of

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

, or can be used to power a

fuel cell A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...

to generate electricity to power an electric propulsor. It cannot be stored in a traditional

wet wing A wet wing (also referred to as ''integral fuel tanks''Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 557. Aviation Supplies & Academics, 1997. ) is an aerospace engineering technique where an aircraft's wing structure is ...

, and

hydrogen tank A hydrogen infrastructure is the infrastructure of points of hydrogen production, truck and pipeline transport, and hydrogen stations for the distribution and sale of hydrogen fuel, and thus a crucial prerequisite before a successful commerciali ...

s have to be housed in the fuselage or be supported by the wing. Hydrogen, which can be produced from

low-carbon power Low-carbon electricity or low-carbon power is electricity produced with substantially lower greenhouse gas emissions over the entire lifecycle than power generation using fossil fuels. The energy transition to low-carbon power is one of the m ...

and can produce

zero emission A zero emission engine, electric motor, motor, process, or other energy source emits no waste products that pollute the environment or disrupt the climate. Zero emission engines Vehicles and other mobile machinery used for transport (over land, sea ...

s, can reduce the

environmental impact of aviation Aircraft engines produce gases, noise, and particulates from fossil fuel combustion, raising environmental concerns over their global effects and their effects on local air quality. Jet airliners contribute to climate change by emitting ...

Airbus Airbus SE ( ; ; ; ) is a Pan-European aerospace corporation. The company's primary business is the design and manufacturing of commercial aircraft but it also has separate Airbus Defence and Space, defence and space and Airbus Helicopters, he ...

plans to launch a first commercial hydrogen-powered aircraft by 2040–2045.

Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...

is less optimistic

McKinsey & Company McKinsey & Company (informally McKinsey or McK) is an American multinational strategy and management consulting firm that offers professional services to corporations, governments, and other organizations. Founded in 1926 by James O. McKinse ...

forecast hydrogen aircraft entering the market in the late 2030s and scaling up through 2050, when they could account for a third of aviation's energy demand.

Hydrogen properties

Hydrogen has a

specific energy Specific energy or massic energy is energy per unit mass. It is also sometimes called gravimetric energy density, which is not to be confused with energy density, which is defined as energy per unit volume. It is used to quantify, for example, st ...

of 119.9 MJ/kg, compared to ~ MJ/kg for usual

liquid fuel Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable ...

s, times higher. However, it has an

energy density In physics, energy density is the quotient between the amount of energy stored in a given system or contained in a given region of space and the volume of the system or region considered. Often only the ''useful'' or extractable energy is measure ...

of 10.05 kJ/L at normal atmospheric pressure and temperature, compared to ~ kJ/L for liquid fuels, times lower. When pressurised to , it reaches 4,500 kJ/L, still times lower than liquid fuels. Cooled at ,

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

has an energy density of 8,491 kJ/L, times lower than liquid fuels.

Aircraft design

The low volumetric energy density of hydrogen poses challenges when designing an aircraft, where weight and exposed surface area are critical. To reduce the size of the tanks

will be used, requiring

cryogenic fuel Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. These fuels are used in machinery that operates in space (e.g. rockets and satellites) where ordinary fuel cannot be used, d ...

tanks A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; t ...

. Cylindrical tanks minimise surface for minimal

thermal insulation Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...

weight, leading towards tanks in the

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

rather than

s in conventional aircraft. Airplane volume and

drag Drag or The Drag may refer to: Places * Drag, Norway, a village in Tysfjord municipality, Nordland, Norway * ''Drág'', the Hungarian name for Dragu Commune in Sălaj County, Romania * Drag (Austin, Texas), the portion of Guadalupe Street a ...

will be increased somewhat by larger fuel tanks. A larger fuselage adds more

skin friction drag Skin friction drag or viscous drag is a type of aerodynamic or hydrodynamic drag, which is resistant force exerted on an object moving in a fluid. Skin friction drag is caused by the viscosity of fluids and is developed from laminar drag to turb ...

due to the extra

wetted area In fluid dynamics, the wetted area is the surface area that interacts with the working fluid or gas. * In maritime use, the wetted area is the area of the watercraft's hull which is immersed in water. This has a direct relationship on the overal ...

. The extra tank weight is offset by dramatically lower liquid hydrogen fuel weight. Gaseous hydrogen may be used for short-haul aircraft. Liquid hydrogen might be needed for long-haul aircraft. Hydrogen's high specific energy means it would need less fuel weight for the same range, ignoring the repercussions of added volume and tank weight. As airliners have a

fuel fraction In aerospace engineering, an aircraft's fuel fraction, fuel weight fraction, or a spacecraft's propellant fraction, is the weight of the fuel or propellant divided by the gross take-off weight of the craft (including propellant): :\ \zeta = \fra ...

of the Maximum Takeoff Weight

MTOW The maximum takeoff weight (MTOW) or maximum gross takeoff weight (MGTOW) or maximum takeoff mass (MTOM) of an aircraft, also known as the maximum structural takeoff weight or maximum structural takeoff mass, is the maximum weight at which the p ...

between 26% for medium-haul to 45% for long-haul, maximum fuel weight could be reduced to % to % of the MTOW.

Fuel cell A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...

s make sense for

general aviation General aviation (GA) is defined by the International Civil Aviation Organization (ICAO) as all civil aviation aircraft operations except for commercial air transport or aerial work, which is defined as specialized aviation services for other ...

and regional aircraft but their engine efficiency is less than large

gas turbine A gas turbine or gas turbine engine is a type of Internal combustion engine#Continuous combustion, continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas gene ...

s. They are more efficient than modern 7 to 90-passenger turboprop airliners such as the DASH 8. The efficiency of a hydrogen-fueled aircraft is a trade-off of the larger wetted area, lower fuel weight, and added tank weight, varying with the aircraft size. Hydrogen is suited for short-range airliners. While longer-range aircraft need new aircraft designs. Liquid hydrogen is one of the best coolants used in engineering, and

precooled jet engine A precooled jet engine is a concept that enables jet engines with turbomachinery, as opposed to ramjets, to be used at high speeds. Precooling restores some or all of the performance degradation of the engine compressor (by preventing rotating sta ...

s have been proposed to use this property for cooling the intake air of

hypersonic aircraft Hypersonic flight is flight through the atmosphere below altitudes of about at Hypersonic speed, speeds greater than Mach 5, a speed where Dissociation (chemistry), dissociation of air begins to become significant and high heat loads exist. Spe ...

, or even for cooling the aircraft's skin itself, particularly for scramjet-powered aircraft. A study in the UK, NAPKIN (New Aviation, Propulsion Knowledge and Innovation Network), with collaboration from

Heathrow Airport Heathrow Airport , also colloquially known as London Heathrow Airport and named ''London Airport'' until 1966, is the primary and largest international airport serving London, the capital and most populous city of England and the United Kingdo ...

Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...

GKN Aerospace GKN Ltd is a British multinational automotive and aerospace components business headquartered in Redditch, England. It was a long-running business known for many decades as Guest, Keen and Nettlefolds. It can trace its origins back to 1759 ...

, and Cranfield Aerospace solutions, has investigated the potential of new hydrogen-powered aircraft designs to reduce the environmental impact of aviation. The aircraft designers have proposed a range of hydrogen-fuelled aircraft concepts, ranging from 7 to 90 seats, exploring the use of hydrogen with

fuel cells A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in req ...

and

gas turbines A gas turbine or gas turbine engine is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the direction of flow: ...

to replace conventional aircraft engines powered by

fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...

. The findings suggest that in the UK hydrogen-powered aircraft could be commercially viable for short-haul and regional flights by the second half of the 2020s with airlines potentially able to replace the entire UK regional fleet with hydrogen aircraft by 2040. However, the report highlighted that national supply, and the price of green liquid hydrogen relative to fossil

kerosene Kerosene, or paraffin, is a combustibility, combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in Aviation fuel, aviation as well as households. Its name derives from the Greek (''kērós'') meaning " ...

are critical factors in determining uptake of hydrogen aircraft by airline operators. Modeling showed that, if hydrogen prices approach $1/kg, hydrogen aircraft uptake could cover almost 100% of the UK domestic market.

Emissions and environmental impact

Hydrogen aircraft using a

design are

in operation, whereas aircraft using hydrogen as a fuel for a

or an

are zero emission for (a

greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

which contributes to global

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

) but not for (a local

air pollutant Air pollution is the presence of substances in the air that are harmful to humans, other living beings or the environment. Pollutants can be gases like ozone or nitrogen oxides or small particles like soot and dust. It affects both outdoor ...

). The burning of hydrogen in air leads to the production of , i.e., the + ½ → reaction in a nitrogen-rich environment also causes the production of . However, hydrogen combustion produces up to 90% less nitrogen oxides than kerosene fuel, and it eliminates the formation of

particulate matter Particulate matter (PM) or particulates are microscopic particles of solid or liquid matter suspended in the air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate matter alone, though it is sometimes defin ...

. If hydrogen is available in quantity from

such as wind or nuclear, its use in aircraft will produce fewer

greenhouse gases Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

than current aircraft: water vapor and a small amount of nitrogen oxide. However, as of 2021, less than 5% of all hydrogen produced is emissions free, and the majority comes from fossil fuels. A 2020 study by the EU

Clean Sky The Clean Sky Joint Undertaking (CSJU) is a public-private partnership between the European Commission and the European aeronautics industry that coordinates and funds research activities to deliver significantly quieter and more environmentally ...

2 and Fuel Cells and Hydrogen 2 Joint Undertakings found that hydrogen could power aircraft by 2035 for short-range aircraft. A short-range aircraft (< ) with hybrid

/Turbines could reduce climate impact by 70–80% for a 20–30% additional cost, a medium-range airliner with H₂ turbines could have a 50–60% reduced climate impact for a 30–40% overcost, and a long-range aircraft (> ) also with H₂ turbines could reduce climate impact by 40–50% for a 40–50% additional cost. Research and development would be required, in aircraft technology and into hydrogen infrastructure, regulations and certification standards. Water vapor is a greenhouse gas – in fact, most of the total

greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...

on earth is due to water vapor. However, in the

troposphere The troposphere is the lowest layer of the atmosphere of Earth. It contains 80% of the total mass of the Atmosphere, planetary atmosphere and 99% of the total mass of water vapor and aerosols, and is where most weather phenomena occur. From the ...

the content of water vapor is not dominated by anthropogenic emissions but rather the natural

water cycle The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth across different reservoirs. The mass of water on Earth remains fai ...

as water does not long remain static in that layer of the atmosphere. This is different in the

stratosphere The stratosphere () is the second-lowest layer of the atmosphere of Earth, located above the troposphere and below the mesosphere. The stratosphere is composed of stratified temperature zones, with the warmer layers of air located higher ...

which – absent human action – would be almost totally dry and still remains relatively devoid of water. If hydrogen is burned and the resulting water vapor is released at stratospheric heights (the

cruising altitude Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical s ...

of some commercial flights is within the stratosphere –

supersonic flight A supersonic aircraft is an aircraft capable of supersonic flight, that is, flying faster than the speed of sound (Mach 1). Supersonic aircraft were developed in the second half of the twentieth century. Supersonic aircraft have been used for r ...

takes place almost entirely at stratospheric altitude), the content of water vapor in the stratosphere is increased. Due to the long

residence time The residence time of a fluid parcel is the total time that the parcel has spent inside a control volume (e.g.: a chemical reactor, a lake, a human body). The residence time of a set of parcels is quantified in terms of the frequency distribu ...

of water vapor at those heights, the long term effects over years or even decades cannot be entirely discounted.

History

Demonstrations

In February 1957, a Martin B-57B of the

NACA The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...

flew on hydrogen for 20 min for one of its two

Wright J65 The Wright J65 was an axial-flow turbojet engine produced by Curtiss-Wright under license from Armstrong Siddeley. A development of the Sapphire, the J65 powered a number of US designs. Design and development Curtiss-Wright purchased a license ...

engines rather than jet fuel. On 15 April 1988, the

Tu-155 The Tupolev Tu-155 is a modified Tupolev Tu-154 (СССР-85035) which was used as an alternative fuel testbed, and was the world's first experimental aircraft operating on hydrogen and later liquid natural gas. The similar Tu-156 was never bui ...

had a hydrogen fuel tank installed in the fuselage, and used a hydrogen fuelled engine in one nacelle, the other two engines were standard an adapted

Tu-154 The Tupolev Tu-154 (; NATO reporting name: "Careless") is a three-engined, medium-range, narrow-body airliner designed in the mid-1960s and manufactured by Tupolev. A workhorse of Soviet and (subsequently) Russian airlines for several decades, ...

airliner.

converted a two-seat

Diamond DA20 The Diamond DV20/DA20 Katana is an Austrian-designed two-seat general aviation light aircraft. Developed and manufactured by Diamond Aircraft, it was originally produced in Austria as the DV20. The DV20 shares many features from the earlier ...

to run on a

designed and built by

Intelligent Energy Intelligent Energy is a fuel cell engineering business focused on the development, manufacture and commercialisation of its proton-exchange membrane fuel cell technologies for a range of markets including automotive, stationary power, materials ...

. It first flew on April 3, 2008. The

Antares Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinisation of names, Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by ...

DLR-H2 is a hydrogen-powered aeroplane from

Lange Aviation Lange Aviation GmbH is a German company that manufactures gliders and develops electric power-plants for other aircraft. It was founded by its present managing director, Axel Lange, in 1996 as Lange Flugzeugbau GmbH in Zweibrücken. The company cu ...

and the

German aerospace center The German Aerospace Center (, abbreviated DLR, literally ''German Center for Air- and Space-flight'') is the national center for aerospace, energy and transportation research of Germany, founded in 1969. It is headquartered in Cologne with 3 ...

. In July 2010, Boeing unveiled its hydrogen powered Phantom Eye UAV, that uses two converted

Ford Motor Company Ford Motor Company (commonly known as Ford) is an American multinational corporation, multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. T ...

piston engines. In 2010, the Rapid 200FC concluded six flight tests fueled by

gaseous hydrogen Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

. The aircraft and the electric and energy system was developed within the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...

's project coordinated by the

Politecnico di Torino The Polytechnic University of Turin (, abbreviated as PoliTO) is the oldest Italian public technical university. The university offers several courses in the fields of Engineering, Architecture, Urban Planning and Industrial Design, and is consi ...

. Hydrogen gas is stored at 350 bar, feeding a fuel cell powering a electric motor along a

lithium polymer battery A lithium polymer battery, or more correctly, lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly, and others), is a rechargeable battery derived from lithium-ion and lithium-metal battery technology. The primary differ ...

pack. On January 11, 2011, an

AeroVironment Global Observer The AeroVironment Global Observer is a concept for a high-altitude, long endurance unmanned aerial vehicle, designed by AeroVironment (AV) to operate as a stratospheric geosynchronous satellite system with regional coverage. Two Global Observer a ...

unmanned aircraft completed its first flight powered by a hydrogen-fueled propulsion system. Developed by Germany's DLR Institute of Engineering Thermodynamics, the DLR HY4 four-seater was powered by a hydrogen fuel cell, its first flight took place on September 29, 2016. It has the possibility to store of hydrogen, 4x11 kW fuel cells and 2x10 kWh batteries. On 19 January 2023,

ZeroAvia ZeroAvia is a British/American hydrogen-electric aircraft developer. The company was founded in 2017 by Valery Miftakhov, who currently serves as the company CEO. ZeroAvia is developing hydrogen-fueled powertrain technology aiming to compete w ...

flew its

Dornier 228 The Dornier 228 is a twin-turboprop STOL utility aircraft, designed and first manufactured by Dornier GmbH (later DASA Dornier, Fairchild-Dornier) from 1981 until 1998. 245 were built in Oberpfaffenhofen, Germany. In 1983, Hindustan Aeronautics ...

testbed with one turboprop replaced by a prototype hydrogen-electric powertrain in the cabin, consisting of two

s and a

lithium-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. Li-ion batteries are characterized by higher specific energy, energ ...

for peak power. The aim is to have a certifiable system by 2025 to power airframes carrying up to 19 passengers over . On 2 March 2023,

Universal Hydrogen Universal Hydrogen was a company co-founded by Jason Chua, John-Paul Clarke, Paul Eremenko and Jon Gordon, who had previously worked together at Airbus and Raytheon Technologies, with the ambition of making hydrogen-powered flight a reality withi ...

flew a

Dash 8 The De Havilland Canada DHC-8, commonly known as the Dash 8, is a series of turboprop-powered regional airliners, introduced by de Havilland Canada (DHC) in 1984. DHC was bought by Boeing in 1986, then by Bombardier in 1992, then by Longv ...

40-passenger testbed with one engine powered by their hydrogen-electric powertrain. The company has received an order from Connect Airlines to convert 75

ATR 72-600 The ATR 72 is a twin-engine turboprop, short-haul regional airliner developed and produced in France and Italy by aircraft manufacturer ATR. The number "72" in its name is derived from the aircraft's typical standard seating capacity of 72 pass ...

with their hydrogen powertrains. On 8 November 2023,

flew a modified

Schempp-Hirth Schempp-Hirth Flugzeugbau GmbH is a glider manufacturer based in Kirchheim unter Teck, Germany. History Martin Schempp founded his own company in Göppingen in 1935, with the assistance of Wolf Hirth. The company was initially called "Sport ...

Arcus-M glider, dubbed the Blue Condor, equipped with a hydrogen combustion engine for the first time, using hydrogen as its sole source of fuel. On 24 June 2024,

Joby Aviation Joby Aviation is a United States venture-backed aviation company, developing an electric vertical takeoff and landing (eVTOL) aircraft that it intends to operate as an air taxi service. Joby Aviation is headquartered in Santa Cruz, California, ...

's S4

eVTOL An electric vertical take-off and landing (eVTOL) aircraft is a variety of VTOL (vertical take-off and landing) aircraft that uses electric power to hover, takeoff and landing, take off, and land vertically. This technology came about owing to m ...

demonstrator, refitted with a hydrogen-electric powertrain in May, completed a record 523 miles non-stop flight, more than triple the range of the battery powered version. It landed with 10% liquid hydrogen fuel remaining in its cyrogenic fuel tank, and the only in-flight emission was water vapor. A hydrogen fuel cell system provided the power for the six electric rotors of the eVTOL during its flight, and a small battery provided added takeoff and landing power.

Aircraft projects

In 1975, Lockheed prepared a study of liquid hydrogen fueled subsonic transport aircraft for

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Langley, exploring airliners carrying 130 passengers over 2,780 km (1500 nmi); 200 passengers over 5,560 km (3,000 nmi); and 400 passengers over 9,265 km (5,000 nmi). Between April 2000 and May 2002, the

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

funded half of the

-led ''Cryoplane'' Study, assessing the configurations, systems, engines, infrastructure, safety, environmental compatibility and transition scenarios. Multiple configurations were envisioned: a 12-passenger

business jet A business jet, private jet, or bizjet is a jet aircraft designed for transporting small groups of people, typically business executives and high-ranking coworker, associates. Business jets are generally designed for faster air travel and more ...

with a range,

regional airliner A regional airliner, commuter airliner or feeder liner is a small airliner that is designed to fly up to 100 passengers on short-haul flights, usually feeding larger carriers' airline hubs from small markets. This class of airliners is typically ...

for 44 passengers over and 70 passengers over , a medium range

narrowbody A narrow-body aircraft or single-aisle aircraft is an airliner arranged along a single aisle, permitting up to 6-abreast seating in a cabin less than in width. In contrast, a wide-body aircraft is a larger airliner usually configured with m ...

aircraft for 185 passengers over and long range

widebody A wide-body aircraft, also known as a twin-aisle aircraft and in the largest cases as a jumbo jet, is an airliner with a fuselage wide enough to accommodate two passenger aisles with seven or more seats abreast. The typical fuselage diameter is . ...

aircraft for 380 to 550 passengers over . In September 2020, Airbus presented three ''ZEROe'' hydrogen-fuelled concepts aiming for commercial service by 2035: a 100-passenger turboprop, a 200-passenger turbofan, and a futuristic design based around a

blended wing body A blended wing body (BWB), also known as blended body, hybrid wing body (HWB) or a lifting aerofoil fuselage, is a fixed-wing aircraft having no clear dividing line between the wings and the main body of the craft. The aircraft has distinct wing ...

. The aircraft are powered by gas turbines rather than fuel cells. In December 2021, the UK Aerospace Technology Institute (ATI) presented its ''FlyZero'' study of cryogenic

used in gas turbines for a 279-passenger design with of range. ATI is supported by Airbus, Rolls-Royce, GKN, Spirit, General Electric, Reaction Engines, Easyjet, NATS,

Belcan Belcan, LLC is a global supplier of engineering, supply chain, technical recruiting and information technology (IT) services to customers in the aerospace, defense, automotive, industrial and government sectors. Headquartered in Cincinnati, Ohio ...

, Eaton,

Mott MacDonald The Mott MacDonald Group is a management, engineering and development consultancy headquartered in the United Kingdom. It employs over 19,000 staff in 150 countries. Mott MacDonald is one of the largest employee-owned companies in the world. ...

and the MTC. In August 2021 the UK Government claimed it was the first to have a Hydrogen Strategy. This report included a suggested strategy for hydrogen powered aircraft along with other transport modes. In March 2022, FlyZero detailed its three concept aircraft: * the 75-seat FZR-1E

has six electric propulsors powered by fuel cells, a size comparable to the

ATR 72 The ATR 72 is a twin-engine turboprop, short-haul regional airliner developed and produced in France and Italy by aircraft manufacturer ATR. The number "72" in its name is derived from the aircraft's typical standard seating capacity of 72 pa ...

with a larger fuselage diameter at compared to to accommodate hydrogen storage, for a cruise and an range; * its FZN-1E

has rear-mounted hydrogen-burning turbofans, a

T-tail A T-tail is an empennage wikt:configuration, configuration in which the tailplane of an aircraft is mounted to the top of the vertical stabilizer, fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs fr ...

and nose-mounted canards, a longer fuselage than the

Airbus A320neo The Airbus A320neo family is an incremental development of the A320 family of narrow-body airliners produced by Airbus. The A320neo family (''neo'' being Greek for "new", as well as an acronym for "new engine option") is based on the Airbus A3 ...

becoming up to wider at the rear to accommodate two cryogenic fuel tanks, and a larger wingspan requiring folding wing-tips for a range with a cruise; * the small

FZM-1G is comparable to the

Boeing 767-200ER The Boeing 767 is an American wide-body airliner developed and manufactured by Boeing Commercial Airplanes. The aircraft was launched as the 7X7 program on July 14, 1978, the prototype first flew on September 26, 1981, and it was certified ...

, flying 279 passengers over , with a wide fuselage diameter closer to the

A350 The Airbus A350 is a flight length, long-range, wide-body twin-engine airliner developed and produced by Airbus. The initial A350 design proposed in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the Airbu ...

777X The Boeing 777X is the latest series of the long-range, wide-body, twin-engine jetliners in the Boeing 777 family from Boeing Commercial Airplanes. The changes for 777X include General Electric GE9X engines, composite wings with folding win ...

, a wingspan within airport gate limits, underwing engines and tanks in front of the wing.

Propulsion projects

In March 2021, Cranfield Aerospace Solutions announced the Project Fresson switched from batteries to hydrogen for the nine-passenger

Britten-Norman Islander The Britten-Norman BN-2 Islander is a British light utility aircraft and regional airliner designed and originally manufactured by Britten-Norman of the United Kingdom. Still in production, the Islander is one of the best-selling commercial airc ...

retrofit for a September 2022 demonstration. Project Fresson is supported by the Aerospace Technology Institute in partnership with the UK

Department for Business, Energy & Industrial Strategy The Department for Business, Energy, and Industrial Strategy (BEIS) was a ministerial department of the United Kingdom Government, from July 2016 to February 2023. The department was formed during a machinery of government change on 14 July ...

and

Innovate UK Innovate UK is the United Kingdom's innovation agency, which provides money and support to organisations to make new products and services. It is a non-departmental public body operating at arm's length from the Government as part of the UK Res ...

Pratt & Whitney Pratt & Whitney is an American aerospace manufacturer with global service operations. It is a subsidiary of RTX Corporation (formerly Raytheon Technologies). Pratt & Whitney's aircraft engines are widely used in both civil aviation (especially ...

wants to associate its

geared turbofan The geared turbofan is a type of turbofan aircraft engine with a planetary gearbox between the low pressure compressor / turbine and the fan, enabling each to spin at its optimum speed. The benefit of the design is lower fuel consumption and m ...

architecture with its Hydrogen Steam Injected, Inter‐Cooled Turbine Engine (HySIITE) project, to avoid carbon dioxide emissions, reduce NO_x emissions by 80%, and reduce fuel consumption by 35% compared with the current jet-fuel PW1100G, for a service entry by 2035 with a compatible airframe. On 21 February 2022, the

US Department of Energy US or Us most often refers to: * Us (pronoun), ''Us'' (pronoun), the objective case of the English first-person plural pronoun ''we'' * US, an abbreviation for the United States US, U.S., Us, us, or u.s. may also refer to: Arts and entertainme ...

through the OPEN21 scheme run by its

Advanced Research Projects Agency-Energy ARPA-E, or Advanced Research Projects Agency–Energy is an agency within the United States Department of Energy tasked with funding the research and development of advanced energy technologies. The goal of the agency is to improve U.S. economic ...

(ARPA-E) awarded P&W $3.8 million for a two-year early stage research initiative, to develop the

combustor A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, burner can, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion ...

and the

heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contac ...

used to recover water vapour in the exhaust stream, injected into the combustor to increase its power, and into the

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps o ...

as an intercooler, and into the

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

as a coolant. In February 2022,

announced a demonstration of a liquid hydrogen-fueled turbofan, with

CFM International CFM International is a Franco-American aircraft engine manufacturer. The company is a joint venture between GE Aerospace and Safran Aircraft Engines (formerly known as Snecma) and is headquartered in Cincinnati, Ohio. It was founded in 1974 to bu ...

modifying the combustor, fuel system and control system of a

GE Passport The General Electric Passport is a turbofan developed by GE Aerospace for large business jets. It was selected in 2010 to power the Bombardier Global 7500 and 8000, first run on June 24, 2013, and first flown in 2015. It was certified in April ...

, mounted on a fuselage pylon on an A380 prototype, for a first flight expected within five years. In April 2025, startup Green Aero Propulsion demonstrated its Blue Dragon turbojet, the first hydrogen based aero engine in India. Key components were additively manufactured, like single piece metal 3D printed liners and critical components. Green Aero previously researched hydrogen injectors and combustion chambers with dedicated test rigs featuring optical access into the combustion chamber enabling a real-time analysis of flame stabilization and flame flash back phenomenon.

Decline

By 2025, multiple projects were scaled down or terminated as major changes are needeed in infrastructure, while hydrogen is also used for power to liquid synthetic sustainable aviation fuel (SAF). Lacking new funding,

closed down in June 2024 while Airbus pushed back its hydrogen-powered projects by five to 10 years, and

Embraer Embraer S.A. () is a Brazilian multinational aerospace corporation. It develops and manufactures aircraft and aviation systems, and provides leasing, equipment, and technical support services. Embraer is the third largest producer of civil air ...

followed.

Proposed aircraft and prototypes

Historical

Lockheed CL-400 Suntan Suntan was the code-name of a prototype reconnaissance aircraft program, with the goal of creating a much faster and higher-altitude successor to the U-2, enabled by the use of liquid hydrogen (LH2) as aircraft fuel. The program was cancelled ...

, 1950's concept, dropped for the

SR-71 The Lockheed SR-71 "Blackbird" is a retired Range (aeronautics), long-range, high-altitude, Mach number, Mach 3+ military strategy, strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Co ...

National Aerospace Plane The Rockwell X-30 was an advanced technology demonstrator project for the National Aero-Space Plane (NASP), part of a United States project to create a single-stage-to-orbit (SSTO) spacecraft and passenger spaceliner. Started in 1986, it was can ...

, 1986–1993 concept with a

scramjet A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully b ...

, cancelled during development *

Tupolev Tu-155 The Tupolev Tu-155 is a modified Tupolev Tu-154 (СССР-85035) which was used as an alternative fuel testbed, and was the world's first experimental aircraft operating on hydrogen and later liquid natural gas. The similar Tu-156 was never bui ...

, 1988 modified Tupolev Tu-154 testbed, flew over 100 flights *

, 2010-2011 fuel-cell powered drone demonstrator, performed 9 flights before crashing *

Boeing Phantom Eye The Boeing Phantom Eye is a High-Altitude Long Endurance, high altitude, long endurance (HALE) liquid hydrogen-powered unmanned aerial vehicle developed by Boeing Phantom Works. The aircraft was Boeing's proposal to meet the demand from the US ...

, 2012-2016 piston engine powered drone demonstrator, flew 9 times with flights lasting up to 9 hours

Projects

AeroDelft
a student team from

Delft University of Technology The Delft University of Technology (TU Delft; ) is the oldest and largest Dutch public university, public Institute of technology, technical university, located in Delft, Netherlands. It specializes in engineering, technology, computing, design, a ...

creating a gaseous and liquid hydrogen fuelled drone and Sling 4. *

ZEROe, presented in late 2020, it aims to create four concept aircraft and launch the first commercial zero-emission aircraft, entering service by 2035
Cellsius H2-Sling
a student project at

ETH Zürich ETH Zurich (; ) is a public university in Zurich, Switzerland. Founded in 1854 with the stated mission to educate engineers and scientists, the university focuses primarily on science, technology, engineering, and mathematics. ETH Zurich ra ...

building a modified Sling HW with a

hydrogen fuel cell A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requ ...

propulsion system. * DLR Smartfish, two seat experimental

lifting body A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift (force), lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as ...

; based on the previous Hyfish model. * DLR HY4, operated by DLR spinoff H2Fly, completed the world's first piloted electric flights powered by liquid hydrogen in 2023 * Project Fresson, a

retrofit. *

Reaction Engines Skylon Skylon was a series of concept designs for a reusable single-stage-to-orbit spaceplane by the British company Reaction Engines Limited, using SABRE (rocket engine), SABRE, a combined-cycle, Air breathing engines, air-breathing rocket propulsion ...

, orbital hydrogen fuelled

spaceplane A spaceplane is a vehicle that can flight, fly and gliding flight, glide as an aircraft in Earth's atmosphere and function as a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbit ...

. *

Reaction Engines A2 LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) was a 36-month European FP6 study to examine ways to produce engines for a Mach number 4-8 hypersonic flight aircraft. The project ended in April 2008. It was funded by the European ...

, antipodal hypersonic jet airliner.
Taifun 17H₂
a student project retrofitting a Valentin Taifun 17E and 17EII with a gaseous

electric propulsion system. *

(fuel cell powered Dash 8-300) the largest aircraft ever to cruise mainly on hydrogen power *

ZeroAvia HyFlyer The Piper M-Class (PA-46; formerly called the Malibu, Malibu Mirage, Malibu Meridian, and Matrix) is a family of American light aircraft manufactured by Piper Aircraft of Vero Beach, Florida. The aircraft are powered by single engines and have ...

(fuel-cell powered Piper PA-46 demonstrator) *

( fuel-cell powered Dornier 228x)Flight Testing Hydrogen-Electric Powerplant
January 19, 2023

References

External links

* * * * {{DEFAULTSORT:Hydrogen Airplane Aircraft configurations Aviation and the environment