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- Hacker News
- blended with standard jet fuel, in a small-scale micro jet engineby SoftTalker
- We shouldn't be burning agricultural products for fuels. We should be electrifying and using synthetic fuels made from CO2 and renewable energy where we can't.by breakyerself
- Around one million coconuts required to fly from Tokyo to Los Angeles.
Around 40 million flights per year.
40 trillion coconuts required for all flights, or 1000x current production.
To scale up coconut production we need 12 billion hectares, or 80% of the Earth's surface for coconut trees.
We need 100k cubic km of water per year, or twice the renewable fresh water on this planet.
Ok cool. We will need to terraform Mars before we can fly by coconut.
Finally I understand the mad billionaire's plan.
by chr15m - Aviation uses around a million metric tons of jet fuel per day.
If you thought habitat destruction from palm oil was bad, that would be nothing compared to coconut oil making up any significant fraction of jet fuel.
by RcouF1uZ4gsC - Part time coconut farmer here.
Adding some numbers for a base line. (Note all of these numbers are almost the upper limit of a well managed farm with very good cultivars)
Best yielding palms yield ~300 nuts per pals at 70 palms/acre.
at 750g a dehusked nut with 20% oil yield
You get ~2.3 tonnes oil/acre.
For reference an a321neo burns around 2,300 kg of fuel per hour when cruising
by parimm - You want a fuel that's chemically identical to current jet fuel, not one burdened with extra oxygen. Yes, this would require more energy, but it would be used more effectively in jets.
A drop-in compatible jet fuel can be made by hydrodeoxygenation of biomass, using Virent's process. The waste cellulose in current US waste streams would be more than enough to displace all current US jet fuel consumption. An extra source of hydrogen would be needed to do this, but hydrogen can be made renewably (and, indeed, that's a good way to provide dispatchable demand to help deal with renewable intermittency, and will have to be done anyway to displace the use of natural gas to make hydrogen.)
by pfdietz - Do coconuts grow particularly efficiently?
Edit: The US created biofuel subsidies a few years ago and it’s led to poor use of land with questionable climate impact. It’s effectively become a wealth transfer to support poor rural American communities, which isn’t necessarily a bad thing but there’re probably more effective ways to do that intentionally.
- 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.
by landl0rd