[alexose]

I've done a decent amount of research on Prometheus Fuels, and I'm a believer.

They've licensed a couple of key technologies out of Oak Ridge. First is a catalyst that converts CO2 + H2O + electricity directly into ethanol. The other is a membrane with parallel carbon nanotubes that are just the right size to filter that ethanol. The rest of the business involves the chemical conversion of pure ethanol into other types of hydrocarbons.

The result is the ability to efficiently create carbon-netural fuel, effectively capturing a percentage of the electricity as gasoline (or jet fuel, etc).

Of course, this is less energy efficient than simply burning fuel that you found in the ground. The advantage is that they can bypass the expensive drilling, refining, and transportation steps and use cheap renewable energy to create fuel literally anywhere they can stick a shipping container.

That's the goal, anyway. I really hope they succeed.

[trhway]

I myself don't like much how my brain sees Musk everywhere, yet I think similar methanol production will first come from SpaceX for Mars.

Also i wonder whether moonshine style distillation is worse than the carbon nanotubes membrane filtration, especially if you have a source of cheap waste heat.

[uranium]

Distillation is pretty expensive, energy-wise, and if you can't run continuously [e.g. if you're trying to use cheap intermittent renewables] you lose energy in the cooling-and-reheating cycles.

I have yet to see a significant source of usable "waste" heat that's not already being used for something else. Low-grade heat isn't helpful--you generally need reasonably high temperature differentials in order to power large-scale industrial processes.

[Disclosure: I've invested in Prometheus Fuels, but don't speak for them.]

[trhway]

>Distillation is pretty expensive, energy-wise,

Moonshining is less than 400 KJ per kg of source, i.e. about 1.5 KWh per kg of ethanol produced from 15% ethanol/water source. Given that one can use waste heat from almost any other industrial process the real monetary cost is way less than the cost of electrical 1.5 KWh.

>I have yet to see a significant source of usable "waste" heat that's not already being used for something else. Low-grade heat isn't helpful--you generally need reasonably high temperature differentials in order to power large-scale industrial processes.

Moonshining is 78 C degree - such cheap waste heat sources are plentiful exactly because it is hard to use for almost anything else.

>you lose energy in the cooling-and-reheating cycles.

not an issue for a 78 C process - basically like your water boiler, takes minimum of thermal isolation.

[corpdronejuly]

Well that answers my question about crypto waste heat and useful work.

[alexose]

How were you able to invest, if you don't mind me asking?

[corpdronejuly]

I've often wondered if I could justify a crypto mining rig if I used the waste heat for something, literally anything, useful. The tech is interesting and I want to for the sake of "doing something cool" but the environmental cost has me iffy on ever trying.

[uranium]

Heat your house?

https://www.newscientist.com/article/mg22530072-800-the-comp...

[corpdronejuly]

Earthship, heatpump, and this... getting pretty close to a dream house TBH.