On my second long haul flight this month I am acutely aware of my carbon footprint growing and wonder what can be done. There are a few candidates:
Hydrogen. I read that Rolls Royce had built a prototype aero engine that can run on Hydrogen. I suspect that it didn’t challenge their engineers too far, as there are hundreds of GGCT power stations that run on gasses. The challenges for H2 include its energy density as a gas which would require a huge plane to make the transatlantic flight, the safety concerns, and the round-trip efficiency of compressing H2. Perhaps it could be used for short flights and replace kerosene on city hoppers?
Electricity is another interesting option, with battery technology advancing and demonstrators already in the air, it certainly could be an answer for the short hops. But like hydrogen the current energy density for batteries makes it impractical for longer flights.
Biofuels could be one of the quickest ways to decarbonise flying. Using fuels like ethanol that have from fermenting plant material is in theory carbon neutral – the carbon emitted is reabsorbed by the plants and so on. But there are already challenges with using land for biofuels and the impact this is having – through competing with land for food or taking wild areas under cultivation.
Synthetic fuels are one more option. Here instead of the fuel coming from fermenting plants the synthetic fuel is created in a chemical plant. There are two key questions for synthetic fuels – firstly where the carbon come from – this could come from carbon capture from another process like cement making. The second question is where the energy comes from, no point in relying on even more fossil fuels to create the fuel.
Aviation has a great opportunity to kick start the synthetic fuels industry. The premium nature of business class flying is not dissimilar to the market entry approach followed by Tesla – ie start with the rich. It would be great to see more trials running to test the viability of this option.
