I can imagine the deserts eventually covered in glass tubes to grow algae for fuel and be sustainable if they can figure out a sustainable nutrients part.

Are you saying that sustainable synthetic fuels can't exist? Or don't current exist? Because those are two very different statements.

Both of those statements are false: synthetic fuels exist now. Last I checked you could buy synthetic fuel for about 2-3 times what regular fuel of the same types cost. Germany was doing synthetic fuels in WWII. South Africa did them when under embargo for their racist policies. Now they are mostly used by racers - where allowed they are enough better to make a win against regular fuel (assuming great drivers and well tuned cars).

The statement was sustainable synthetic fuels. Synthesizing from other fossil fuels like coal or natural gas definitely doesn't qualify.

Maybe, but all you really need is a source of CO for the process to work. Coal or natural gas are easy sources, but with some energy input we can make it from CO2, Photosynthesis is the most obvious way.

Sustainable really depends on how much we need. There is probably enough wind energy for the process, so long as we only use it for things where high energy density is needed. That means drive an EV car or electrified transit, but we can use synthetic fuel for airplanes. Maybe, this last is mostly my guess, it is a real problem to work on.

Well, it requires a lot of power, so building a large plant will be difficult and expensive.

> building a large plant will be difficult and expensive.

Utility scale renewables are in pennies pwr kWh in Levelized Cost, and continually dropping.

There are 10kWh/liter of jet fuel. Utility scale solar is 3c/kWh LCOE today.

Assuming a pessimistic 10% efficiency in electricity to synthetic jet fuel conversion via H2 hydrolysis and the Fischer Tropsch process, that's a hypothetical $3/liter of synthetic jet fuel.

Current petroleum based jet fuel is $1.50/liter.

If you improve the conversion efficiency to 20% and lower the LCOE of utility scale solar to 1c/kWh (projected by 2050), and the hypothetical liter of synthetic jet fuel drops to 50c/liter, all while petroleum jet-fuel grows increasingly scarce and more expensive.

The efficiency of synfuel production could rise significantly as the efficiency of feedstocks like H2 hydrolysis (already 50%+) increase, and if if CO for Fischer Tropsch can be sourced from biomass instead of sourcing it from atmospheric CO2.

Finally, it's likely that in the future we'll switch to using hydrogen directly as an aviation fuel, bypassing hydrocarbons altogether, at which point the electricity to air conversion efficiency nears 80%.

At those prices, you can begin to afford to overbuild renewable capacity to drive a synfuel pipeline to store that energy chemically, which we will arguably need to do for seasonal energy storage anyways.

On top of what danans calculates, they are currently researching solar reactors that convert biomass directly into biofuel with sunlight, skipping the losses and costs of converting sunlight to electricity with regular PV solar.

> is there a synthetic fuel plant with zero impact at any scale already? No, this is just wasting more fuel for the heck of it

cool, so you're on board with nuclear + hydro as a more sustainable base load solution than lithium-based batteries

I would love a future where we are making everything nuclear, including synthetic fuel. However this is nowhere near reality. You need high temperature reactor to make this viable.

Lithium based batteries don't produce power.

Did replygirl say they did? To my reading they are talking about using batteries to store and deliver baseline energy from intermittent sources like wind and solar.

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