The future of sustainable aviation might at last have its champion. If we want to decarbonise our energy system and replace fossil fuels swiftly we need to focus our attention on hydrogen power. Fortunately, this change is already in
Fear of hydrogen, which is dating back to the Hindenburg Zeppelin explosion in 1937, labelled hydrogen as dangerous. However, we have come a long way since then and understanding that the current situation is unsustainable is pushing the
world towards hydrogen as a clean version of a better society.
What is hydrogen power?
Hydrogen’s role in the path to sustainability was recognised from the start, both by the scientific community and the International Energy Agency (IEA). Hydrogen is an efficient method of energy storage with zero carbon dioxide and
greenhouse gas emissions.
Hydrogen is an energy vector, like electricity. It is a means of transporting energy from where it is produced to where it is used. An example of this is producing hydrogen at a power station, to power a vehicle. Hydrogen is
considered a potential component of a sustainable energy economy because the only combustion product is water, not carbon dioxide (CO2).
‘Hydrogen is an efficient method of energy storage with zero carbon dioxide and greenhouse gas emissions.’
Despite hydrogen being the most abundant element in the universe, unfortunately, there are no easily obtainable sources on Earth, so hydrogen needs to be produced somehow. Hydrogen can be produced through electrolysis by separating water
into hydrogen and oxygen. The image below shows an electrolyzer with two chambers with an electrically charged anode and cathode to drive the separations of molecules.
On the other hand, electric aviation is currently not seen as feasible due to concerns including battery weight and the amount of power needed for takeoff, with the latest example being Rolls-Royce's 'spirit of innovation'. This works fine
for a one-seater aircraft (and looks majestic too), but the battery life and power capacity simply are not there for commercial flight.
The future of aviation with hydrogen power
Aviation is a hard-to-decarbonise field, with technologies at a very immature stage of development and unfortunately, solar power is only possible for ultra-light aircraft.
Burning hydrogen directly is gaining a lot of traction. In the aviation sector, which produces two-to-three percent of current global CO2 emissions, electric and pure hydrogen aircraft could become important drivers for sky
especially for short-distance routes.
‘Electric aviation is currently not seen as feasible due to concerns including battery weight and the amount of power needed for takeoff.’
Airbus has recently shown how serious they are about hydrogen; announcing three concept designs for hydrogen aircraft which could fly by the year 2035, known as the ZEROe aircraft. These aircraft concepts are powered by hybrid systems which combine
hydrogen gas turbines with electric-powered cells. This way electricity is generated from hydrogen tanks.
Hydrogen combustion is an excellent way to make use of existing hydrocarbon-burning technologies. However, water is still emitted as a product of combustion. Water vapour can become a greenhouse gas in the form of contrails under the right
conditions. Therefore, in order to achieve 'true net-zero' conditions, nothing should be released into the atmosphere at all, including water vapour. Hydrogen fuel cells (the opposite process to electrolysis producing electricity from
hydrogen to power electric motors) and hybrid hydrogen-electric battery technologies are being developed for the future.
Challenges facing hydrogen power
One of the main challenges of the sustainable aviation industry is fueling. At the moment, there is a lack of hydrogen supplying infrastructure to airports. Refuelling time for hydrogen is longer in comparison to conventional fuels and
aircrafts would need structure and aerodynamics modifications to carry larger volumes of fuel.
It is also prudent to ensure the safety of hydrogen meets current high-standards in the aviation industry. In open areas, the risk of ignition is low as hydrogen is rapidly dispersed into the atmosphere before it can ignite. The problem
occurs when storing hydrogen in an aircraft tank; hydrogen needs to be stored at very high pressure, and these tanks need to be pressurised, in order to prevent leaking or bursting.
‘One of the main challenges of the sustainable aviation industry is fueling.’
The European Hydrogen Safety Panel (EHSP) and projects such as the Hydrogen Safety for Energy Applications (HySEA) are developing recommendations to improve international standards for hydrogen safety procedures and bring forward the energy
The EU Hydrogen Strategy for a carbon-neutral Europe is, fortunately, paving the way and it has written 2050 goals of decarbonisation; aimed to progress the hydrogen technology.
The first phase runs to 2024 and aims to produce one million tons of green hydrogen. The final phase runs from 2030 to 2050 when green hydrogen technology is streamlined to a large scale.
Benefits of hydrogen over electricity
Stored hydrogen is currently less efficient than storing electricity, particularly lithium-ion batteries, so why bother? There are applications for which electric motors and batteries are just too heavy for the power and battery life
Transmitting electricity under the sea can also be a challenge, with very heavy and expensive to install cabling required for high power transmission. Pipes for hydrogen transport can be much simpler and more cost-effective in contrast.
This can open up the potential for hydrogen production in offshore wind farms which would be too far from land for economical electricity production. In this case, hydrogen would need to be produced at the wind farm (e.g. by electrolysis),
and transmitted to shore through pipes.
‘There are applications for which electric motors and batteries are just too heavy for the power and battery life available.’
Hydrogen has the potential to take off in a big way, providing it continues to get support from governments and economies. Research needs to continue to improve hydrogen production and storage to help the aviation industry to decarbonise.
Aircraft will also need to be adapted and new safety standards will need to be written. Perhaps after overcoming these obstacles aviation can say goodbye to fossil fuels.