Hydrogen-powered aircraft open up opportunities for fossil-free travel, and technology is developing rapidly. New studies from Chalmers show that almost all air travel within a 1,200-kilometer radius can be done with hydrogen-powered aircraft by 2045 – and with the help of a completely new type of heat exchanger, the range will also increase significantly.
– If it goes well, it can happen quickly now. As early as 2028, the first commercial hydrogen flights in Sweden could be in the air, says Tomas Grönstedt, professor at Chalmers and director of the TechForH2* competence center at Chalmers.
The tailwind is also felt inside Chalmers' wind tunnel laboratory, where researchers test airflow conditions in advanced turbine and compressor systems. Here, more energy-efficient engines and technology are being developed that pave the way for a transition to safe and efficient hydrogen operation for heavy vehicles.
For hydrogen-powered aviation, short and medium-distance journeys are the closest in sight. A recently published study from Chalmers shows that hydrogen-powered aviation could meet the needs of 97 percent of all intra-Nordic flights and 58 percent of Nordic passenger volume by 2045. The researchers assumed a range of 1,200 kilometers and that an existing aircraft model was adapted for hydrogen operation. The study, led by doctoral student Christian Svensson in Tomas Grönstedt's research group, also presents a fuel tank that holds enough fuel for the entire flight distance, is sufficiently insulated to keep the super-cold liquid hydrogen and is at the same time lighter than today's fossil-based systems.
Heat exchangers benefit from cold fuel
For longer flights, the industry expects to continue using the same type of turbofan engines as in today's aircraft, which means that the fuel system must be adapted to handle the cold of liquid hydrogen. To keep the weight of the aircraft down, the hydrogen needs to be stored in liquid form, which requires a temperature in the tank of around -250 degrees. Injecting such cold fuel for combustion means a significantly reduced effect, with increased fuel consumption as a result.
To address this challenge, researchers at Chalmers have been working for several years to develop a completely new type of heat exchanger. The technology, which is now patent-pending by partner GKN Aerospace, takes advantage of hydrogen's low storage temperature to cool engine parts, and then uses waste heat from the exhaust gases to preheat the fuel several hundred degrees before it is injected into the combustion chamber.
– Every degree of temperature increase reduces fuel consumption and increases range. We were able to show that short- and medium-haul aircraft equipped with the new heat exchanger could reduce their fuel consumption by almost eight percent. Considering that an aircraft engine is a mature and well-established technology, this is a very good result from a single component, says Carlos Xisto, associate professor at the Department of Fluid Dynamics at Chalmers and one of the authors of a recently published scientific article.
The researchers also note that with more optimization, this type of heat exchanger technology in a standard Airbus A320 commercial aircraft could provide an improved range of up to ten percent, or equivalent to the Gothenburg-Berlin route (equivalent to approximately 750 kilometers).
Big investments, big challenges
The work to develop solutions for future hydrogen aviation is being done on a broad front, and when the innovation cluster Swedish hydrogen development center, SHDC, recently held a seminar, several Chalmers researchers participated together with actors from both academia and industry. Several commercial companies testified to major investments in hydrogen aviation in the coming years. The technology is well advanced. The challenges lie rather in the large investments required, and in developing infrastructure, business models and partnerships to be able to produce, transport and store the hydrogen so that the transition becomes possible. A total transition to hydrogen aviation is expected to require approximately 100 million tons of green hydrogen annually.
– There are industry expectations that 30–40 percent of global aviation will be powered by hydrogen by 2050. We will likely need a mix of aircraft that run on electricity, less environmentally damaging e-jet fuel and hydrogen for a number of years to come. But every aircraft that can be powered by hydrogen from renewable energy reduces carbon dioxide emissions, says Tomas Grönstedt.
Within TechForH2, there are good conditions to tackle the hydrogen challenge on a broad front, and with a budget of SEK 162 million, the competence center can contribute to development in a number of different research areas that connect to hydrogen and heavy transport.
– We are also noticing a great deal of interest in our courses in the new Mobility Engineering master's program here at Chalmers, which is very gratifying. You could easily say that we have a tailwind now, says Tomas Grönstedt.
According to the press release.
