E-Fan X

The channel crossing of Airbus’ E-Fan electric aircraft demonstrates that flying without petroleum jet fuel is possible. Image via Airbus

APEX Insight: Commercial airlines won’t be weaning off petrol anytime soon, but the industry is experimenting with renewable energy sources to power parts inside the cabin.

As our digital devices work around the clock, we are moving further into an age of high power demand and dependency. We are, at the same time, more conscious of the impact our energy consumption has on the environment. We want to enjoy the limitless possibilities of technology, but we also want to do it sustainably. In the quest for greener power, we look for alternative solutions in the sun and the wind, as well as in the elements.

The successful around-the-world tour of the Solar Impulse aircraft and the channel crossing of Airbus’ E-Fan electric aircraft demonstrate that flying without petroleum jet fuel is possible. Indeed, Airbus, Rolls-Royce and Siemens have announced a plan to develop a commercially viable hybrid regional passenger jet by the 2030s, and Boeing is also conducting research on the viability of hybrid electric aircraft. But, as Barnaby Law, Airbus’ fuel cell and hydrogen technology program director, explains, reaching the goal of hybrid electric flight is like climbing a stairway, not running a dash: Each step up the path forms the foundation for the next. 

Law has been researching hydrogen fuel cell technology at the ZAL TechCenter in Hamburg for approximately six years. While the research being conducted today is forward-thinking, Law says it is vital for the aviation industry to think generations ahead. “Airbus has been working on this topic for 15 years,” he says. “The reason that we’re investing so much is that, if we develop new aircraft, we have to think 50 to 100 years into the future. If you think back 50 to 100 years, we still had steam trains and horse-drawn carriages. So, we have to be very conscious about what could be a future fuel and what the emission requirements will be.”

“We have to think 50 to 100 years into the future.” – Barnaby Law, Airbus

Law says the properties of hydrogen fuel cells are promising for auxiliary power units (APUs) in aircraft and, ultimately, for propulsion. They are advantageous because their weight is lower than tanks of jet fuel in relation to their power output. In other words, they run more efficiently and quietly, while reducing CO2 emissions.

“Liquid hydrogen could be a future fuel. It doesn’t have to be the only fuel but it’s a strong contender,” Law says. He describes progress on fuel cells as a series of building blocks working toward development of an APU replacement, which would use the same interfaces as existing APUs, and run on the ground at the airport without producing noise or carbon emissions. 

Brianna Jackson, communications specialist at Boeing Research & Technology, says Boeing is committed to investigating new technologies that will deliver greater fuel efficiency and environmentally progressive innovations. This commitment is reflected in a variety of partnerships and special programs.

“We work with industry partners, government and academia to explore and develop technologies that will benefit our existing and future products,” Jackson says. “Currently, we are studying a wide range of possible future applications for electric aircraft, from small aircraft to large airliners, both inside Boeing and with partners such as NASA, propulsion companies and universities; this research includes fuel cells, power inverters and other components for more electric subsystems and eventually primary aircraft propulsion.”

If powered by sustainable sources, electric and hybrid electric propulsion systems could offer significant environmental benefits, and reductions in fuel, noise and cost. “Environmental benefits are dependent on improving the performance and weight of electrical components and energy storage,” Jackson says. “The successful deployment of regional and larger commercial aircraft will be paced by the development of improved batteries and electric components: motors, controllers, generators, distribution systems.”

“We might see smaller hybrid electric jets for regional travel in the 2020s.” – Brianna Jackson, Boeing Research & Technology

Like Law, Jackson says the timeline for adoption of electric systems will evolve in stages. “We might see smaller hybrid electric jets for regional travel in the 2020s and short-range commercial aircraft – like a regional airliner or small version of a Boeing 737 – operating in the 2030s. It is worth noting that large long-range commercial aircraft, like the Boeing 777 or 787, are unlikely to be displaced by electric aircraft in the foreseeable future.”

While it’s common to think of power in terms of big-picture goals, like powering aircraft, much of the energy needed day-to-day is for other noncritical systems. Take, for example, the significantly higher demand for power outlets on aircraft to charge electronic devices. After all, we rely on our smartphones, tablets and laptops not only as productivity tools, but also as extensions of or replacements for the in-flight entertainment system. Power sources that make electrical systems more efficient can help distribute power to a greater number of passengers for longer, without interfering with critical flight systems.

In 2015, B/E Aerospace was short-listed for a Crystal Cabin Award for a solar window shade with USB power outlets, called Solar Eclipse, which could put sunshine to good use for passengers seated by the window. Meanwhile, Diehl Aerosystems’ Crystal Cabin award-winning DACAPO (Distributed Autonomous Cabin Power) concept is designed to supply the cabin with electrical energy generated by a power cell inside the company’s MAGIC (Modular Autonomous Galley with Integrated power Cell), which runs on a mixture of propylene glycol and water.

The fuel cell galley kitchens will be ready for production in a few years’ time.

“Energy limitations today restrict the simultaneous operation of galley insert consumers (like coffee makers, ovens, chillers),” Ronny A. Knepple, head of Energy Systems, Diehl Aerospace, says. “Catering processes must be tailored to these constraints today. Our concept, including a load management function, enables the simultaneous use of all consumers in such a galley and supports more-flexible operations on board.” The fuel cell galley kitchens will be ready for production in a few years’ time, and can be introduced into aircraft and airport processes with little change.

There were three key drivers to Diehl’s vision for an energy-efficient cabin, Knepple shares. “First, environmental requirements – our concept uses clean, quiet and sustainable energy resources, so it’s green. Second, technical requirements – it facilitates numerous new cabin comfort features, as well as the transition to the more electric aircraft architecture, which requires significantly more electrical energy. And third, flexibility requirements – in order to make it easier to adapt the passenger cabin to market requirements, new conditions must be created for easier aviation certification of the components used.”

From solar and alternative fuels to new power sources, the industry is working on bringing more power to the skies and on board. Florian Pillath, systems engineer, ZAL Center of Applied Aeronautical, responsible for the development and management of the fuel cell systems test bench at the ZAL TechCenter, says what he enjoys most about his role is pushing the future forward. “Every experiment, there is something coming that you didn’t expect, but you can use it. There’s so much potential in fuel cell systems, but you have to do the research and the development,” Pillath says. The industry has flipped the switch on alternative power and has no plans to turn it off.

“Future Proof”  was originally published in the 8.1 February/March issue of APEX Experience magazine.

Marisa Garcia was once locked in a hangar in Oberpfaffenhofen while fine-tuning Gandalf’s new seats. Seriously. The firemen got her out. Writing is less confining, but she has lovely memories of those hands-on days.