[no_wizard]

This all sounds amazing but it also gives me Theranos vibes. While I understand the general science around this has been around a long time (the aforementioned Fischer Tropsch process) I would love for this to get some independent scientific validation before I'm willing to buy in to their dream here. It just "feels" too good to be true. Even with the Faraday Reactor considerations

Seems much more scientifically plausible however. I'm just a natural skeptic.

[photochemsyn]

Theranos never produced a working prototype of a microfluidic measurement device that could do what they were claiming, and their investors were foolish enough to pour their money in without doing that basic due diligence, for various reasons that have been well-dissected in the past.

I think here they would really have to get a working prototype / pilot plant up and running, with a transparent demonstration. That's how the Haber process got support from Bosch c. 1909.

https://en.wikipedia.org/wiki/History_of_the_Haber_process

Generally speaking however, industrial processes run with pure streams of ingredients are more efficient. The rate-limiting step in the process as they describe it looks like the first one, because they're just using 400 ppm CO2 air as the input, with no pre-concentration. You'd need some kind of energy return on energy investment, i.e. how much electricity input per liter of produced fuel, plus lifetime of the catalyst etc. to make sense of how plausible it is.

[Osiris30]

Relevant thread - question asked by Ramez Naam on the feasibility of Prometheus:

https://twitter.com/ramez/status/1516199169911713794?s=21&t=...

[Folcon]

> Bluntly? They are a running joke among anybody that has been around the renewable fuels space for longer than a couple years.

> There are no shortcuts around the physics required to assemble a molecule.

So the process is viable, but the cost is prohibitive?

[molyss]

I just don’t understand the answer. Seems to be conflating “energy cost” and “financial cost” under the same umbrella. I don’t think Prometheus is disputing the energy costs of “the physics required to assemble a molecule”.

Current processes use heat+pressure, which are pretty wasteful, and often rely on burning fossil fuels in the 1st place, which will mechanically increase the financial cost”

What I understand from Prometheus is that they have a different way to “assemble molecules”, which relies on “electrocatalysts” instead of “catalysts requiring high temperature and pressure”. On the face of it, I can totally see how such a catalyst would decrease the “financial cost” without necessarily impacting the “energy cost”. It’s simply using a cheaper energy than the current processes.

The twitter answer rings similar to someone who would say “There is no shortcuts around the physics of producing light” to justify why LED lightbulbs would never make it. Most of the energy of incandescent bulbs is just heat, and there are physical process that produce light without all that heat. I don’t see any reasons why the extra heat would be needed to produce fuels

[Folcon]

Yes, the whole thing is a bit weird and so I honestly don't know which side is credible.

[DennisP]

You can't get around the basic energy requirements, but don't we come up with easier synthesis methods all the time?

[thinkcontext]

You aren't the only one. This recent article captured a lot of skepticism from people in the field. And then there's history of optomistic predictions, in 2018 McGinnis predicted they'd be undercutting gasoline in 2019.

https://www.technologyreview.com/2022/04/25/1050899/promethe...

[fswd]

The theranos vibes you're feeling I believe is from a "flaw" they make an assumption solar is 1 or 2 cents a kilowatt-hour. This isn't true (maybe with subsidies IDK) but it costs more to ship solar panels, and the wiring, fuses, breaker box, charge controller, adds a huge significant cost. You can't just take a panel cost and divide it by the watts without this in consideration. And the land cost. And unless you live in Arizona you will have very low utilization.

BUT... when I lived on the grid I paid $.13/kwh. At 77kwh per gallon that puts us at $10.01/gallon. It is unknown if this is just syn gas or ethanol, or what the BTU of that gallon is. And this definitely isn't diesel, which would have the biggest impact. I know when my friend did bitcoin mining he was able to get $.03kwh so... let's use that 77 * .03 = $2.31. So between $10 and $3 a gallon is actually possible.

With gas over $5 or $6 (the company is in Santa Cruz? Their gas is probably $7 or $8 at this moment, I bet) ... this will work

The other issues are... United States uses 30TW of oil a day (convert barrels of oil to BTU and convert BTU to watt hours... to convert oil used per day in watts to speak of)... and 10TW of electricity a day.

To replace 'fossil' fuels we'd need ...70TW of electricity after inefficiency conversion.

There isn't enough copper, nickle, and silver to make all those solar panels. There isn't enough public support or political capital to build nuclear reactors either. This is another flaw.

Another commentor suggested, just replacing Russian's oil at 4 million barrels a day. That's possible. And it makes it exciting.

[ncmncm]

There is, in fact, plenty of copper. You don't need nickel or silver to make or place solar panels. Prices are still falling fast. Nowadays they don't even bother to tilt them to match latitude, so mounting has got very, very cheap.

The price of electricity is variable, sometimes negative. You would not need to produce at levelized cost, but only when the sun is shining.

[elil17]

The U.S. "Sunshot" program sets USD$0.03/kWh as the target levelized cost for 2030 utility solar. At the moment that number is USD$0.06/kWh.

If they used power only at production peaks and colocated with generation (saving ~10% line losses), $0.02/kWh seems in the realm of the possible.

As to lack of resources to build enough solar capacity, concentrator plants make that a non-issue.

[ncmncm]

Concentrator plants cost much more -- i.e., 3x -- than PV. They can still be useful for producing process heat instead of electric power.

[seltzered_]

I think the other tradeoff over the long run is long-run lifetime costs of replacing "solar panels, and the wiring, fuses, breaker box, charge controller" under the assumption that these aspects do have lifetime costs and are at best rebuildable and at worst produce waste (e.g. think about how Vaclav Smil calls wind turbines 'the perfect embodiment of fossil fuels' - https://www.youtube.com/watch?v=gkj_91IJVBk&feature=youtu.be... ).

It's important to ask these questions of what the tradeoffs really are when thinking about Energy Returned on Energy Invested, whether e-fuels would actually decrease new car production (i.e. older cars get used longer if e-fuels really make sense), the political economy ramifications if these things really worked, etc.

In prior waves of interest of things like algae-based fuels (see https://www.greentechmedia.com/articles/read/lessons-from-th... ), my rough understanding is that they could be done but the numbers just didn't work out.

Finally, it's really worth pointing out the concern of any of these things falling under solutionism when also thinking about the state of our planet from a more integrated framework such as the planetary boundaries: https://www.stockholmresilience.org/research/planetary-bound...