The buzz over clean fuel is gaining ground in the aviation sector. In late April, some of the biggest multinationals came together to launch a body called the Sustainable Aviation Buyers Alliance (SABA) to accelerate investment in sustainable aviation fuel for zero-emission flights in the future. Some of its founders include Netflix, JPMorgan Chase, Microsoft, Boeing and Boston Consulting Group. US-based non-profit Rocky Mountain Institute (RMI) and Environmental Defence Fund, who work in the area of sustainability, are spearheading this movement.

According to RMI, nearly 2.5 per cent of today’s emissions are a result of global air travel — a figure that is projected to rise rapidly in the coming years, especially as the demand for jet fuel is expected to double from pre-pandemic levels by 2050. To cite an example, a one-way flight from New York to London emits one tonne of carbon dioxide per passenger, according to various estimates.

One of the main reasons for the setting up of SABA is that most big companies have their own fleet of aircraft and have to account for their own aviation emissions.

So, what are the ways airlines can hope to reduce carbon emissions? One major solution that is drawing the attention of late is the use of hydrogen fuel cells as fuel for operating aircraft.

The aviation industry, being hugely safety conscious, is also asset-heavy and has hence slowed down transformations as compared to other sectors, says Professor Satya Chakravarthy, co-founder and CTO, The ePlane Company. “This is where interest in bio-fuels (presumably renewable with net-zero carbon footprint), hydrogen, fuel cells, hybrid electric and electric propulsion concepts have come into play,” the professor, who is on a sabbatical from IIT, Madras, tells BusinessLine .

Stephane Fymat, vice president and general manager, Unmanned Aerial Systems, Honeywell Aerospace, says that although aircraft are more fuel-efficient and greener than before, the industry still relies heavily on fossil fuel. For a greener future, it is important to understand the relevance of Hydrogen fuel cells. A fuel cell works by converting stored chemical energy into electricity, much like a battery.

Hydrogen has been in the spotlight of late, and the airline industry is taking note of its benefits. Airbus plans to develop the world’s first zero-emission commercial aircraft by 2035, Fymat says.

According to reports, the US-based startup ZeroAvia plans to manufacture a 10- to 20-passenger aircraft powered by hydrogen fuel cells by 2024. It has already received $5 million in grants from three UK government programmes and has drawn the interest of 12 regional carriers in the UK, the US and the European Union. According to a press statement from the company, it is also launching the development programme for a 2MW hydrogen-electric powertrain for a full-size regional aircraft. The programme kick-off is supported by a funding of $24.3 million from different investors.

Chakravarthy believes that in the future, aircraft will use electric and hybrid-electric power. But Fymat stresses hydrogen fuel cells are more relevant because they carry more “juice”. A complete hydrogen fuel cell propulsion system can hold three to five times more energy than the equivalent mass battery electric system. Properly designed, it weighs less and is more compact than an equivalent battery-electric system, particularly for longer-range applications beyond 50-60 miles, he adds.

He points out that a battery-electric flight today is limited to short-range hops of 20-150 miles. A hydrogen fuel cell propulsion system can expand this reach by three to five times. Plus, hydrogen fuel cells can be refuelled at a pump in 5-10 minutes; today’s batteries need to be charged for 30-45 minutes.

Higher energy density, lower weight, greater reach and faster turnaround times can translate to big savings, he adds. The high energy density of hydrogen fuel cells allows them to compete directly against combustion solutions. Hydrogen fuel cell propulsion can reduce aviation’s climate impact by 75-90 per cent, Fymat believes.

Chakravarthy points out that hydrogen involves safety concerns, storage and handling and voluminous tanks that have to fit into aircraft . “Both hydrogen and fuel cells drive up the cost in a sector that is already running on wafer-thin margins. So, we are looking at a longer time frame for its adoption,” the co-founder of e-Plane says.

Till better alternatives emerges, hydrogen is a path to zero-emission flights.

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