Biofuels in airplanes: how aviation wants to become clean

Status: 06/22/2022 10:44 a.m

Global aviation must also massively reduce its CO2 emissions in order to achieve climate targets. Biofuels for aircraft have come into focus. How far is the industry?

By Michael Immel, ARD aviation expert

How can we fly as climate-neutrally as possible in the future? This question will be one of the major topics at the International Aerospace Exhibition (ILA) in Berlin in the coming days. For the industry, it is about more than a green coat of paint. Airlines, airports and industry have long understood that they have to deliver now. Political buzzwords like “energy transition in the sky” have long been dominating the agenda. But how will airplanes be powered in the future? With hydrogen? electric? That is still completely unclear. And so the focus is currently on biofuels, which are intended to replace climate-damaging kerosene in the medium term.

The target is clear: Aviation should be clean by 2050 – climate-neutral and sustainable. CO2 emissions must be reduced. And so biofuels, known in the industry as SAF (“Sustainable Aviation Fuel”), are currently the first choice. Because these alternative fuels can be mixed with fossil fuels without any problems. Engines do not have to be retrofitted for this. Airlines around the world successfully flew tests with SAF admixtures more than a decade ago. But biofuel is still a niche product as it is much more expensive than conventional kerosene.

“The future technologies in aviation to save greenhouse gases are the key to a successful location and the achievement of the Paris climate goals,” says Green politician Anna Christmann, the federal government’s coordinator for aerospace. She speaks of a “joint effort” that is now necessary to achieve the goal of climate-neutral aviation as quickly and comprehensively as possible.

Pilot plant for synthetic kerosene

SAF can be produced using a variety of processes. For example, from leftovers, from liquid waste fats, waste from agriculture and forestry can also be used for this. Another way is synthetic power-to-liquid (PtL) fuels, which can be produced from hydrogen and the CO2 in the ambient air. This requires a lot of renewable energy. PtL kerosene is currently considered a promising technology.

“Today, PtL kerosene is definitely still much more expensive than bio-SAF,” says Manfred Aigner, SAF project manager at the German Aerospace Center (DLR). “We don’t yet have a factory that produces PtL in large quantities, so we don’t know the exact price yet. But if we look ten years into the future and then have large production facilities, then PtL should be cheaper than organic SAF,” believes Aigner, who has been researching for more than two decades as Director of the DLR Institute of Combustion Technology.

According to a private operator, what is currently being built a few kilometers from Frankfurt Airport is the world’s largest production plant for synthetic fuels. The location in the Frankfurt-Höchst industrial park appears favorable, because the carbon dioxide produced there can be used together with hydrogen (which is produced from “green electricity”) for the production of sustainable kerosene. Planned annual capacity: 3500 tons. It’s about gaining experience for industrial mass production, says Hesse’s Economics and Transport Minister Tarek Al-Wazir.

Huge demand for biokerosene

In Germany alone, around ten million tons of kerosene are flown every year. In order to meet the Paris climate targets, the federal government has stipulated, among other things, a statutory quota of two percent PtL by 2030. That corresponds to 200,000 tons of climate-friendly kerosene. An ambitious goal. “It will be very difficult to reach the 2030 target, but I am convinced that we must try to at least come close,” says Aigner. If Germany were to miss the target by a year, the world would not end immediately. “If we don’t make any effort to achieve the goal now, then we won’t achieve it in 2040 either,” the scientist is certain.

The EU is also pushing for sustainable flying in Europe. A “Fit for 55” climate package provides for a continuously increasing blending quota for sustainable fuels for flights departing from the EU. The EU is planning a mandatory quota of two percent from 2025, and by 2050 at least 63 percent should be added. The package is not decided yet.

“Build Back Better” is now the motto in the United States. US President Joe Biden wants to restructure the economy ecologically, in line with the Paris climate agreement. In North America, all flights are to be operated with SAF biofuels by 2050. The Department of Energy in Washington calculates that the annual forest and agricultural waste is sufficient to produce more than 60 billion liters of SAF. That would cover a good three quarters of today’s US demand for kerosene.

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