Fossil fuels and flying

A few years ago, in a discussion with Tourism Industry Aotearoa (TIA), I learned that the two things that kept TIA awake at night were ‘terrorism’ and ‘climate change’. Obviously, added to that, would now be ‘global pandemic’. But let’s focus for now on the ‘climate change’ concern.

You may have seen Air New Zealand’s latest initiative that they are calling ‘flight NZ0’ that is all about aligning Air New Zealand’s operations with a carbon zero future. This includes Air New Zealand investing massively in algae-based synthetic paraffinic kerosene research. This appears to be an excellent step in the right direction, with a clear focus on pursuing the development and use of Sustainable Aviation Fuel (SAF). Aviation biofuel, bio-jet-fuel, or bio-aviation fuel are all types of SAF. Last year more than 100 million litres of SAF were produced, used primarily in fuel blends (commercial airlines are allowed to blend up to 50% biofuels with conventional jet fuel), with around 14 billion litres in forward purchase agreements. Production of aviation biofuel is likely to become a significant industry in the coming years and has the potential to reduce carbon emissions by 85% compared with traditional jet fuel.

Some people may be surprised at my support for Air New Zealand going in this direction; many climate scientists and environmentalists see flying as about as sinful as pushing kittens through a woodchipper. But, as you may have noticed in the ‘five commandments of climate change’ piece I wrote back in December, flying was never raised to the level of being a climate sin. There is nothing inherently wrong with flying. In fact, flying has made the world a smaller place, has allowed families spread around the world to visit each other easily, is a cornerstone of the tourism industry, has created a globally connected economy, and has created a more integrated international society which has probably saved millions of lives through avoided wars.

Unfortunately, planes burn aviation fuel which, to date, is generated almost exclusively using fossil fuels as a source. So, if we could just avoid that one little issue of flying resulting in the transfer of carbon atoms from the ground and into the atmosphere, we could, to first order, fly to our heart’s content. I say ‘to first order’ because there is the issue of ‘embedded carbon’ in the construction of aircraft, airports, etc.

While battery-powered aircraft may be suitable for short-haul flights, their energy storage-to-weight ratio makes them unsuitable for medium and long-haul flights. Therefore, absent some radical new energy technology, liquid aviation fuels for medium and long-haul flights are likely to be necessary for decades to come – and we simply cannot afford to have those be fossil-fuel based. Because the chemical and physical characteristics of SAFs are almost identical to those of traditional jet fuel, a clear advantage of using SAFs is the ability to use existing aircraft and all existing infrastructure.

Currently, fossil jet fuel production costs around NZ$1 per litre based on a barrel of crude oil costing around NZ$150. SAF costs around NZ$2.5 per litre, so it only becomes competitive with fossil jet fuel if the price of oil starts nudging NZ$375 per barrel. That said, the price of SAFs is expected to drop as new technologies for their production come online, while the price of fossil jet fuel is expected to rise as the environmental costs of their use start to be folded into their price, e.g., through emissions trading schemes. At some time within the next decade or two, SAFs may become economically competitive with fossil jet fuel.

There are different ways to produce SAFs. One is to catalytically convert CO₂ from CO₂-rich airstreams (e.g., from smokestacks) into feedstock liquids such as ethanol and ethylene, noting that small piston engines used in aircraft can be modified to burn ethanol. There is some very exciting research going on at Auckland University along these lines.

You may not realise it, but you may very well be contributing to the research required to bring about a SAF-powered aviation future. There is a company called LanzaTech that have developed methods for producing alcohol-to-jet synthetic paraffinic kerosene (ATJ-SPK) from ethanol produced from carbon monoxide in flue gases using microbes, and the New Zealand Superannuation Fund (the home of some of your tax dollars) invests in LanzaTech. LanzaTech has successfully demonstrated its methods in a pilot plant in New Zealand using industrial waste gases from the steel industry as a feedstock for its microbial fermentation.

Another way to produce SAFs is to convert solid biomass into liquid biofuel. Pyrolysis processes are used to produce pyrolysis oil, or gasification to produce a syngas, which is then processed into so-called Fischer–Tropsch synthetic paraffinic kerosene (FT-SPK). New Zealand generates huge amounts of forestry waste (slash) each year that could be used as a biomass source for producing these FT-SPK fuels. Depending on which type of biomass is used, this can lower CO₂ emissions by 20–98% compared to conventional jet fuel; the use of forestry residues to produce FT-SPK results in between 91% and 95% savings in CO₂ emissions.

Being able to generate SAFs inexpensively could be a silver bullet to addressing much of the impact of aviation on the climate system. The International Energy Agency forecast SAF production to grow from 18 to 75 billion litres between 2025 and 2040, representing a share of aviation fuel between 5% and 19%. All of this could be some light at the end of the tunnel for the New Zealand tourism industry who will increasingly need to manage the challenges of climate-related ‘travel guilt’.

Thank you again for making it to the end of this piece. If there are specific issues you would like me to write about, or specific challenges that your business is facing when it comes to reducing your climate footprint, or establishing your climate credentials, please let me know (greg@bodekerscientific.com). I would like to do whatever I can to help.