Keys to Decarbonisation, Part 2: Biofuels vs. Hydrogen


In a recent post we discussed the increasing use of biofuels in commercial aviation. Longer term, however, the airline industry is looking toward another fuel source: hydrogen. In September 202o Airbus announced its future commitment to hydrogen as a future fuel source for the aircraft it manufactures – to power their engines as well as supply onboard electricity hithertofore supplied by generators in the engines. Its main competitor, U.S. manufacturer Boeing, responded by asserting that hydrogen technology is still insufficiently developed and that the only practicable solution in the meantime is SAF (sustainable aviation fuel) – another name for biofuel – derived from energy crops and algae as well as waste including cooking oil, food scraps; discarded packaging; and waste wood. Airbus does agrees with this assessment to some extent, as the first test of its hydrogen tech will not even start until 2025, and even then only affecting basic components such as hydrogen tanks and pipes.

Yet now, though, we have single-seat experimental models already flying. The energy demand of these models is much less, and they use hydrogen batteries to generate the electricity which feeds the engines.The first, which flew in Spain, was a project of Boeing Research & Technology Europe , which has had its headquarters in Madrid since it was founded in 2002. The capacity of these batteries, however is still far from sufficient to power a commercial  passenger airliner.

Used hydrogen, as well as SAF, is considered “green” in that it’s renewable, produced by eletrolysing water. Nonetheless, according to Airbus, this type of hydrogen comprises just one percent of that produced in the entire world. But investment in electrolysis plants is increasing – by 50 times during the second half of this decade – and by 2050 they’re expected to ne anle to supply 25 perent of the world’s energy needs.

There are now around 400 electrolysis plant projects underway, and that number is increasing all the time, representing around 200 megawatts in the process of installation. Even so, according to Airbus data, in Europe today around one gigawatt is being generated today (around 20 megawatts annually per plant), with between 1.5 and 2.3 GW from various planned projects, for a total of at least 40 GW/year by 2030 – up to ten billion tonnes of green hydrogen. Meanwhile, the new plants planned until 2023 will have an average production capacity of 100 MW/year.

Other parts of the world are following suit. Australia, for its part, has projects underway which could be responsible for 30 GW/year, while in Asia they’re looking at more than 10 MW/year within a decade.

And Airbus points out that the process of turning megawatts into gigawatts will reduce the costs of production. According to a report from the International Renewable Energy Agency (IREA), they’ve already begun to drop, by up to 40 percent in the short term; to become truly competitive, they’ll need to drop by 80 percent over the longer term.

Meanwhile, the issue with SAF costs is the same; it can supposedly reduce carbon emissions by up to 80 percent, but currently a litre of this fuel is still three to eight timee more expensive than kerosene (from which petrol is distilled). And partly as a result of this, we’re a long way from reducing emissions at that rate.

In addition, projects to offset emissions are usually financed by a supplement in airline ticket fares, going toward ongoing schemes including planting trees and reforesting damaged areas in various parts of the world; installation of solar panels; and the supply of efficient stoves at affordable prices to avoid the use of bonfires for cooking, as burning wood means more deforestation as well as CO₂ emissions. An hourlong flight of an Airbus A320 or Boeing 737, emits around 65 kilos of CO₂ per passenger, and that can be offset by planting .4 trees per passenger – or using between 30 and 35 litres of biofuel.