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Comment by willtemperley | Hacker News Reader

That infographic says it uses 16-20% more fuel per unit of thrust. That's a significant amount more weight for an aircraft to carry, but because carrying extra fuel also burns fuel, extra fuel use would compound exponentially. This would probably mean significantly more than 20% extra fuel would be required for long-haul flights.

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Ouch.

There's one plantation of under 1000 hectares in Papua New Guinea that makes biodiesel from coconut oil to power their own operation and vehicles on the island.[1] But they don't export. On an island with few energy sources, the process makes sense.

This is more like an industrial process that self-powers from its own waste. Sewerage treatment plants do that - the process produces methane, often enough to power the plant. Not enough to put them into the gas business, though.

Amusingly, corn to ethanol plants in the US do not generally self-power. They consume natural gas to produce ethanol.[2] Net energy gain is maybe 1.3. Only subsidies keep this going. About 40% of US corn production goes into this boondoggle.

Sugar cane, though - that's a win for biomass.

[1] https://www.theguardian.com/world/article/2024/may/10/png-co...

[2] https://en.wikipedia.org/wiki/Ethanol_fuel_energy_balance

Biofuel as a side venture that makes a bit of profit / saves on a bit of fuel outlay has always been a thing in Australia also.

Currently, off the top of recent memory:

* Australia is exploring using canola to produce sustainable aviation and renewable diesel fuels, potentially creating 7,000+ jobs by 2030. - Landline (June 2025) https://www.youtube.com/watch?v=fIwsfxK6jw0

* North Queensland graziers are trialling a 10-hectare pongamia plantation to run alongside livestock. (July 2026) - https://www.abc.net.au/news/2026-07-19/pongamia-tree-aviatio...

* Agave is climate change resistant and has promise beyond just tequila - (May 2026) - https://www.abc.net.au/news/2026-05-23/australia-agave-farmi...

* Adelaide will turn 600,000 tons of forest waste into 140 megaliters of jet fuel per year, enough for 4.5M passenger seats. - (July 2026) - https://www.youtube.com/watch?v=z0u91oQ-hjY

The relative perspective on 4.5M passenger seats is that at one point in the recent past (possibly pre COVID) there were ~ 1M passengers in the air globally at any random time.

On the business investment and development side there are several operators, eg: JetZero Australia - https://jetzero.com.au/projects

^^^ this

I cringe thinking about more biofuel ideas getting forced through. Sure, let’s all spend a ton of petroleum energy on fertilizing, farm equipment, and processing, and raise food prices by using all the land for producing ethanol-corn, and jet fuel coconuts, just to get a slightly worse petroleum replacement fuel.

There's always the air-gasoline route. That's right! With enough chemical engineering and materials science, we can extract jet fuel from air and water. You extract out CO2 from the air, and H2 from water. You turn the CO2 and hydrogen into carbon monoxide, and then Fischer-Tropsch chemistry and some other magic gets you hydrocarbons out the other end! The problem is the economics of that process can't compete with oil from the ground.

> The problem is the economics of that process can't compete with oil from the ground.

Even factoring in emissions?

Given oil from the ground is adding long buried CO2 to and steadily increasing atmospheric insulation whereas fuel-from-air is using what is already there.

Is this another example of discussions about oil not factoring in the negative externalities to make it look good?

NileRed, is that you? ;)

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