A hydrogen powered aircraft uses hydrogen rather than fossil fuels such as aviation fuel. Hydrogen can either be burned in a jet engine or can be used to power a fuel cell which generates electricity. Liquid hydrogen has about four times the volume for the same amount of energy of kerosene requiring need of larger fuselage length and diameter for storage. Increased surface area lowers performance significantly due to increased friction and drag. However, hydrogen is about one-third of the weight of kerosene jet-fuel for the same amount of energy. Therefore the performance is a trade-off of the larger wetted area and lower fuel weight.
History and Present
You will be surprised to know that as early as in February 1957, a Martin B-57B flew on hydrogen for 20 min for one of its two Wright J65 engines. On 15 April 1988, the Tu-155 first flew as the first hydrogen-powered experimental aircraft. More recent progress have been made by Austria’s Diamond Aircraft Industries to successfully test-fly it’s flagship 2-seater, DA20 with hydrogen powered fuel cells. Due to present-day impending horror of global warming, mega-manufacturers like Airbus and Boeing have been forced to look into ways to decarbonise aviation industry. In 2020, Airbus announced plans to develop three different hydrogen-fuelled concepts, named ZEROe, with the aim of developing zero-emission aircraft powered using hydrogen gas turbine rather than hydrogen fuel cells.
Are other stakeholders making aviation industry a scapegoat ?
Before the pandemic grounded most flights, commercial aviation accounted for about 2.5% of global emissions of carbon dioxide. It sounds like a small proportion of the whole, but it is more than those of Germany (2.2%), and this is not the whole story. Carbon dioxide accounts for about half of aviation’s contribution to what is known as its effective radiative forcing – that is, its total contribution to the factors that actually drive a rise in global average temperature. Contrails – water vapour trails from aircraft – are aviation’s largest other factor.
Are hydrogen powered engines completely emission-free ?
There is the question of whether hydrogen can be produced at scale and at a competitive price without itself having a large carbon footprint. The great majority of hydrogen used in industry today is created using fossil fuel methane, releasing carbon dioxide as a waste product. Hydrogen can be produced from water through a process called electrolysis, driven by renewable power, but this process is currently expensive and requires large amounts of energy. Only about 1% of hydrogen is produced this way at present.
Will there be enough hydrogen for all ?
Investment in electrolysers – the “clean” technology used to separate hydrogen and oxygen atoms in water – is booming worldwide. As a result, green hydrogen production capacity could achieve a 50-fold increase in the next six years, according to some estimates. This means green hydrogen could be on track to supply up to 25% of the world’s energy needs by 2050.
And this rapid and cost-effective scale-up could not be more timely: drastic solutions are now urgently required if the world is to meet the 1.5-degree Celsius target of the Paris Agreement.
Sanctioned projects at a glance
The International Energy Agency (IEA)’s Hydrogen Projects Database counts nearly 320 new green hydrogen production demonstration projects worldwide. This amounts to a total of about 200 MW of added electrolyser capacity. And new projects are being added on almost a weekly basis.
At present, Europe has less than 1 GW/year of electrolyser installed capacity. However, the European Commission recently announced longer-term plans to install at least 40 GW of electrolyser capacity or up to 10 million megatons of green hydrogen by 2030. As part of these plans, larger electrolysers – with up to 100 MW capacity as opposed to the current 20 MW capacity – are expected to be built by 2024 and installed next to demand centres.
Australia has one of the world’s highest volumes of green hydrogen production capacity, including about 30 GW of projects in the pipeline. In Asia, the region’s electrolyser capacity could reach +10 GW over the coming decade, driven by demand from Japan, South Korea and China. Across the pond, the USA is also starting to catch up with plans to develop green hydrogen mega-projects in California, Texas and Utah.
According to a report released by the International Renewable Energy Agency (IRENA), green hydrogen production costs have already begun to fall largely due to a decline in renewable energy costs and further cost savings in electrolysis facilities.
Getting green hydrogen to airports: how will it work ?
Green hydrogen is an energy pathway that forms a critical part of strategy to lead the decarbonisation of the aviation industry. This means architecting the future green hydrogen ecosystem for aviation will need to start now in preparation of an entry-into-service of hydrogen aircraft in near future. According to Airbus, it could look something like this.
For now, one thing remains almost certain: hydrogen and E fuels are likely to continue to be substantially more expensive than conventional jet fuel for years or decades to come, limiting their role in greening aviation – unless the other costs of aviation come to be weighed differently.