Have you ever wondered why renewable fuels are so important to make aviation sustainable? And why we at Carbyon are working hard to make this a viable transition scheme? We invite you to have a look at this short, but very informative animation video!

As a scientist I like to discover how stuff works. How do certain inputs relate to certain outputs. So when Hans asked if I could help to unveil how the chemistry for an direct air capture application worked I thought: ‘sure, no problem.’ That’s how I started on this journey. After an initial deep-dive into the literature I discovered how naive that first exclamation was. I gained some perspective of how many variables came into play. Gained insight into how these variables influenced the kinetics and stability of sorbents in the direct air capture process. We’ve unveiled not only simple straight forward influences, but also first- and second- order interaction effects. Optimising the chemistry for stability and yield while also keeping in mind the energetic cost for this process quickly unveiled itself to be a vast optimization problem. It is similar to being a blind man tasked with finding the highest mountain peak in a mountainous country.
When starting a daunting task like that you don’t just climb every mountain in the country, that would take way too long. We started by observing how large the mountain base of every mountain was, how steep the initial slope. (Okay this also might take a long time, my metaphor might not be perfect, but for now I’ll stick with it.) That’s how we determined a few mountains that would be most likely to have high peaks. That’s how we started our search. We have already climbed some mountains and still have more climbing to do. But with every climb we do we understand our process better. We get a better grasp on the chemistry of direct air capture. And we get a small step closer to a climate neutral economy.

Our climate is changing, we know it is caused by our emissions of CO2 and yet each year we emit more CO2 than the year before. Seemingly technology is not able to keep up with our way of life and despite the efforts of many individuals, humanity as a whole is not willing or able to change its way of life in order to reduce the emissions.

Flying is a nice example. Very few people are willing to give up flying while we all know it is a major cause of CO2 emissions, approaching 1 Billion ton of CO2 per year. So either we all stop flying which does not seem very realistic or we find a way to make flying CO2-neutral.

The problem is not the lack of renewable energy. There is more than enough wind and solar energy to power our society. The problem is that electricity is not backward compatible with the way we currently use energy. Airplanes do not fly on electricity. Only 20% of our energy appliances run on electricity. 80% run on energy carriers derived from fossil oil and gas.

So there are two ways forward. Either we re-invent all our appliance such that they can all run on electricity. Or we convert electricity into an energy carrier that is backward compatible with the existing appliances.

I believe we are focusing too much on the first one: trying to change the appliances in order to run on electricity. It is a long and slow process. We should by all means continue these efforts but it is time to start working on the second approach as well: converting electricity into an energy carrier that is backward compatible with existing appliances. We no longer have the luxury to go for one option – we should endorse all technical options we have, including the conversion of electricity to backward compatible fuels.

People have argued that the conversion of electricity into backward compatible energy carriers like gasoline, kerosene or diesel is a bad idea because you loose part of your energy during the conversion process. While very true, this argument does not hold very strong. There is plenty of renewable energy and we have developed technologies like wind and solar that manage to harvest it very efficient and at ever lower costs. New solar farms in the Middle-East are able to produce electricity at a cost of 1,5 Eurocent/kWh for 2000 hours per year and this cost keeps getting lower.

The spectacular cost reduction of solar electricity is the result of upscaled production in China. The same will happen with electrolysis equipment, allowing to lower the costs of renewable hydrogen. When we are able to complement this with a cost-effective technology to harvest CO2 from air, we are very close to a technology that allows to convert this electricity into renewable fuels that can compete with fossil fuels.


Modern airplanes use kerosene and emit CO2 as they burn kerosene in their jet engines. Flying is therefore one of the human activities that contributes to global warming. Direct emissions from aviation are more than 2% of worldwide emissions.

Kerosene usage by the aviation industry is set to grow by approximately 2.5 – 3.5% every year for the next 30 years in Europe. For these figures we take into account the growth in passengers and freight and we compensate for efficiency gains. Compared to 2017, kerosene usage would easily double towards 2050 and could even rise to up to 5 times current levels, if efficiency gains would not be realised. Already in 2009 the International Air Transport Association (IATA) set a goal to halve CO2 emissions by 2050 with respect to 2005. Without additional measures projections are a factor of 6 – 10 times worse than what IATA is aiming for.

Set ambitions in the aviation sector, as of yet, depend on new break-through measures as far as emission reduction is concerned. As a society we do not seem to want to give up our freedom to travel long distances nor our desire to get packages from around the globe on our doorstep quickly. So if we do not want to fly less, we need to find a solution that meets – and ultimately goes beyond – IATA’s long-term target.

[source: Quintel and Kalavasta have explored many pathways towards a carbon neutral society. Report carbon neutral aviation.]

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