4 ms·
This isn't proper SAF, it's basically C8/10 biodiesel. No aromatics which is one of the perennial problems with SAF, due not just to volumetric energy density
by landl0rd 1mo ago
This isn't proper SAF, it's basically C8/10 biodiesel. No aromatics which is one of the perennial problems with SAF, due not just to volumetric energy density but nitrile seals not swelling enough. Integral wing tank seals usually expect aromatic exposure also. This is why some of the catalytic routes/CHJ are of greater interest, cycloparaffins/napthenes recover some of this vs a more biodiesel-ish blend, but even 50% cycloparaffin doesn't fully recover swell. These are solvable backwards compatibility issues but not in the short or medium term.
More egregiously FAME is a polar solvent that eats your elastomers, even some fluoroelastomers. It will also attack your polysulfide tank sealant. The remark that it's "technically feasible" to decrease oxygen through hydrogenation is not at all sufficient. Now you're into requiring catalyst beds and a hydrogen plant which makes this much less appealing. Plus ester instability when you sink heat into fuel. Plus freeze point. This is literally a tracked contaminant banned above mg/kg levels that doesn't even have very good properties otherwise they want to run as a major constituent of fuels.
- shrx 1mo agoMaybe it's time to develop new sealing materials? edit: thanks for the downvote. I should've said "Maybe it's time to _invest into developing_ new sealing materials?" ;)
- Brian_K_White 1mo agoMaybe they should have said something like "These are solvable backwards compatibility issues, but not in the short or medium term."
- panny 1mo agoMaybe it's time to stop burning food as fuel. What are the jets going to do anyway, bomb Iranian children? Remember when George W Bush signed into law the corn ethanol bill. Corn tripled in price within 8 years. Fuel didn't get cheaper. In fact it cost more to produce the ethanol.
- JoeAltmaier 1mo agoAll water under the bridge. Ethanol is now a paying proposition. And it uses corn we used to dump.
- stuaxo 1mo agoFair play, also we need to stop using palm oil in food.
- Walf 1mo agoBut how else am I going get orangutan flavour in my ice c̶r̶e̶a̶m̶ confection?
- ecshafer 1mo agoEthanol was always a political thing, and not technical. It was passed because it would triple the price of corn.
- pajko 1mo agoNot just corn. Farmers would grow more corn in place of other plants reducing the supply, and shorter supply generally means higher prices, This is happening in India right now.
- stackghost 1mo agoAviation is notorious for having long product cycles. Look at how long GA pilots have been spraying their communities with lead. There's simply no economic feasibility to replace every seal on every aircraft.
- lazide 1mo agoWhy can’t they synthesize aromatics too? they’re usually shorter chain, seems like they should be easier if nothing else?