07/11/2024
Airbus and Toshiba recently announced a technology research partnership to investigate the feasibility of developing a 2-MegaWatt superconducting motor for use in future hydrogen-powered aircraft.
The announcement follows the earlier launch of Airbus’s ZEROe project which, as touched on in our previous blog, aims to bring to market hydrogen-powered commercial aircraft by 2035. This includes aircraft with gas turbine engines modified to combust hydrogen, and electric aircraft powered by hydrogen fuel cells. To reduce pollution and help reach net-zero targets, it is hoped that hydrogen-powered aircraft will represent a significant share of the commercial aircraft market by 2050.
The potential advantages of using a superconducting electrical machine require little explanation: superconducting electrical machines have near-zero I2R losses; they can operate with a higher current density and thus reach power and torque densities higher than those achievable by permanent magnet machines; and they do not come with some of the challenging fault modes that come with a permanently excited rotor.
Proposals to use superconducting electrical machines in transport applications, aircraft included, are not new. An Internet search will reveal various projects and literature going back over a decade. Despite this, proposals to utilize superconducting machines in transport applications have not got off the ground. There are at least a few reasons for this:
- A superconducting electrical machine would necessarily require an on-board cryogenic cooling system with a low-temperature cryogen such as liquid helium or hydrogen. The resulting mass, cost and complexity is a high price to pay for the efficiency gains.
- Superconducting magnetic systems are notoriously sensitive. At present, their use is mostly limited to lab-based applications and stationary applications such as medical imaging. Bringing a superconducting magnetic system into a much less controlled environment will be challenging, especially given the stringent certification requirements associated with commercial aircraft.
Airbus and Toshiba will not be blind to these challenges. They do, perhaps, start from a better position than many earlier attempts. Future hydrogen-powered aircraft will, by design, already have an on-board source of cryogen, which helps. Perhaps more importantly, the significant financial cost and project resources associated with solving the technical challenges of storing and distributing hydrogen in a commercial aircraft can be borne through the wider ZEROe project, and can be addressed at a platform level. The Airbus and Toshiba project may therefore focus on the design and operation of a superconducting motor without too much concern about how the cryogenic coolant will be stored and supplied to the motor, or indeed the wider impact on the aircraft.
Patent Filing Trends
We can get an idea of patenting trends in this sector with a simple patent search, looking for published patent applications having an IPC/CPC Classification of B64C (Aeroplanes; Helicopters) or B64D (Equipment for Fitting in or to Aircraft; Arrangements or Mounting of Power Plants or Propulsion Transmissions in Aircraft) and which include the terms “superconducting” and “electrical machine” or “motor” in the title, abstract or claims. The following shows the number of published patent families by priority year for 2011-2023 – note that the total for 2023 is extrapolated based on the incomplete data currently available for that year.
It is hard to draw any firm conclusions, but it appears there was a spike in interest in aerospace superconducting electrical machines from 2017 to 2019, giving way to a more significant increase since 2021. The more recent increase may well be driven by the heightened interest in hydrogen-powered aircraft – see, for example, the recent publications EP 4439972 A1 (Airbus), EP 4389606 A1 (Hamilton Sundstrand) and US 2024/271833 A1 (General Electric).
It is likely that most of the earlier patents relating to superconducting electrical machines will have expired by the time hydrogen-powered aircraft enter into service, estimated to be 2035-2040 at the earliest. However, patent applications filed in the next 5 years – particularly those concerned with the general integration of a superconducting electrical machine into a hydrogen-powered aircraft – may well be foundational and, if still in force in 2045-50, potentially of great value. It will be interesting to follow how the numbers increase in the coming years, and whether the efforts of Airbus and Toshiba bear fruit.
This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.
