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.

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.

50 MTons of coconut oil are produced per year (approximately). Is this a significant amount, compared to oil derived from crude (where gas currently comes from).

How many coconuts do we need to support current aviation needs? I’m guessing it’s not likely this will work economically?

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.)

If it burns more fuel, how is it "about as efficient"? That doesn't seem to make much sense to me.

> New research found that aviation biofuel made from coconut oil can power a small jet engine about as efficiently as traditional jet fuel, with lower unburned hydrocarbon emissions, though the blends burn more fuel and emit slightly more carbon monoxide.

I think this is awesome. Anything we can do to get away from burning fossil fuel is a win in my book. I don’t know about this particular effort, but it seems to me that aviation could really need some big wins in this direction. Last I looked we still run smaller planes on leaded fuel. Crazy.

So we can't have the dark chocolate Bounty bar anymore but we can use coconuts to fuel planes?

This isn't the future I want.

But why? I don't know of a case where biofuels aren't a disaster against the stated environmental purpose. Bailouts for farmers? Sure. A good way to generate green energy? I think engineered algae comes kind of close to making sense as an oil source, but as a fuel would still seem silly to me. Please correct me if I'm wrong.

blended with standard jet fuel, in a small-scale micro jet engine

How is the viscosity at -60?

> This study used oil from material the researchers describe as discarded and non-edible, including the large seeds and leftover flesh, so the fuel draws on parts of the crop that would otherwise go to waste.

This statement seems disingenuous. Surely they did not invent a novel way to extract coconut oil as part of this study and not choose to publish it. Surely this is just existing byproduct that already has plenty of commercial use.

If you look at how many coconut plantations you would need to make even a measurable dent in jet fuel demand, this would be an unmitigated environmental disaster.

I want to solve climate change as much as the next guy, but chopping down all our tropical rainforests to make it happen sacrifices exactly what we're trying to save.

either wait for bigger batteries, hydrogen or some super efficient material to create the fuselage.

biofuels won't work. they take too much land and are inefficient in terms of producing.

Cue defense industrial base funded influencer campaign to promote the "dangers" of medium chain triglycerides.

Long life to coconut revolution, in Bougainville island!

Will this produce better smells?

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.

The issue with bio fuel is the following: Due to climate change the overall area for food production in the world is shrinking. Bio fuel is directly competing with food.

The solution: Ditch carbon based fuels as much as possible and replace it with electric transport.

I know that it's currently unviable to use electric aircraft in almost all use cases except short range drones. But then the solution to that problem is to rely less on air travel and transport and use land based alternatives.

This is about vectors and incentives. Investing in bio fuels to get a 100% replacement for fossil fuels is not going to work and it only stalls what actually needs to happen which is a radical transport system change.

we've been working on biofuel to replace fossils forever, hopefully it leads to something if not jet fuel specifically.

Yeah, but until it matches kerosene in price and availability (how many coconuts per aeronautical mile?) it won't actually be an alternative

This is absolutely nuts!

Maybe those cargo cult guys were onto something

So we just cut down some ancient rainforests to grow them right? Works for Palm oil! Goooo Planet!