7 ms·

I wish that the 3 law of thermodynamics laws were more commonly taught... because here you are battling the 2nd and the 1st. A calculation by Jean Marc Jancovi

I wish that the 3 law of thermodynamics laws were more commonly taught... because here you are battling the 2nd and the 1st. A calculation by Jean Marc Jancovici showed that for a small airport (GVA in this case) you'd need half a dozen nuclear reactors just to produce the fuel for departing flights. That's obviously assuming this kind of technology is functioning and has 100% yield. I'm not saying that these technologies are not to be pursued, but thinking that we (the rich) can keep flying as much as now due to a miracle technology is unsupported by Science, to say the least. ps: i did 2 postdocs in material science trying to improve various industrial/energy technologies. there's no miracle.

steve76 4y ago
kaibee 4y ago
Solar is cheaper than nuclear and still getting cheaper, so looking at what you'd need in terms of nuclear reactors is likely to be misleading.
- defterGoose 4y ago
  I don't even want to think about how much surface area you'd need for solar panels intended to replace 6 megawatt-scale nuclear reactors, but I'm guessing football fields is the wrong unit to use... Last time I checked, land wasn't cheap and they weren't making any more of it.
  - immmmmm 4y ago
    yeah and there's crop failure coming decades in advance compared to IPCC's predictions, so better not using crop space.
    - pwinnski 4y ago
      Some of that crop failure is due to heat, which could be mitigated by using solar panels to provide shade. That doesn't work for all crops, some of which require direct sun, but it works for more than I expected.
      - ncmncm 4y ago
        No crops require 100% direct sun. Maize and wheat yield is reduced a bit, without, but the year-round revenue from solar panels easily exceeds the difference.
  - adgjlsfhk1 4y ago
    Land isn't cheap, but there's a lot of land that can have a solar panel on top of it without causing problems. A good place to start is every building roof.
    - pfdietz 4y ago
      Land is, in fact, cheap in very many places. If one were making fuel with the solar energy you wouldn't put the solar in places where land was expensive, since the fuel would be highly transportable.
  - incrudible 4y ago
    > I don't even want to think about... I'd call that an argument from laziness. > Last time I checked, land wasn't cheap and they weren't making any more of it. Land that is remote, not fertile and that doesn't harbor any natural resources is actually rather cheap. Moreover, "they" are making more land in certain coastal areas where land is expensive.
  - usrusr 4y ago
    Regarding land use, just yesterday I was pondering about what technology it would take to create survivable off shore solar. Some loose grid of floating collectors happily bouncing on the waves like a flock of resting seabirds, perhaps cleverly reeling in and out link and anchor lines to match the geometry of the waves? Or just the right amount of springyness, dynamically tuned to the wave situation? Then it occurred to me that even nature hasn't really solved ocean surface plants, what could be a more clear indicator that it's a really hard problem...
    - ncmncm 4y ago
      We have plenty of calm freshwater sites for solar, so there will be no need for ocean solar.
  - Kon5ole 4y ago
    The correct unit to use is parking lots. If you base this unit on the current area used for parking in the USA, you can even use centi-parkinglots ;-)
  - guiomie 4y ago
    SF Reservoir has 12 football fields worth of solar panels and generates 4.5 megawatts.
    - kaiwen1 4y ago
      It generates zero megawatts far more often than 4.5 megawatts. 4.5 is peak on the best days. 0 is assured for several hours every day.
      - guiomie 4y ago
        Thanks for added details. I was wondering if this project was efficient considering the amount of "fog" in this area.
  - bluGill 4y ago
    When algee biofuels were first proposed someone calculated that Arizona could produce all the fuel we use on currently unused land. The limit is our ability to scale algee, but the lab results also show that the numbers are right.
  - pfdietz 4y ago
    Yes, you didn't think about how much surface area, since if you did you'd realize it wasn't a big problem.
  - adrianN 4y ago
    (I assume you mean GW not MW, because MW is very little for a proper power plant). Solar panels produce about 200Wp/sqm. In Germany they average to about 12% of peak production over a year, so say 22W/sqm averaged. 6GW continuous is then about 51k football fields[1]. I assume that the US has lots of land that is much sunnier than Germany, so you can probably get away with fewer football fields. [1] https://www.wolframalpha.com/input?i=%286GW%2F%2820W+per+square+meter%29%29+%2F+%28area+of+a++football+field%29 https://www.wolframalpha.com/input?i=%286GW%2F%2820W+per+squ...
- nine_k 4y ago
  What area would it take to produce several GW that a few reactors would produce? In clear weather, a surface perpendicular to the sunlight gets about 1 kW / m². So 1 GW would take a square kilometer. If our solar cells are top-notch 25% efficient cells, 1 GW will take 4 km² at best weather. And we need many multiples of that. Verily, Sahara must be the best place for such an oil factory. Maybe some of the US Midwest and West, with many sunny days. And, unlike the cute pictures on the side, they will need to be massive, all the way to the horizon. Maybe with a few nuclear plants thrown in if we learn to build them efficiently again.
  - rootusrootus 4y ago
    > What area would it take to produce several GW that a few reactors would produce? Out of curiosity, I tried some napkin math on this. If Nevada went whole hog, used say, 1% of their total land for solar, they could produce almost half the electrical needs of the US, if I haven't mucked up the math too much. Sounds plausible, but 1% of Nevada's land for solar would indeed be 'all the way to the horizon' in many places.
    - ncmncm 4y ago
      That number is a bit low, but area for solar panels will never be in short supply, because the same land can be used as is used for other things.
  - immmmmm 4y ago
    let's assume we can scale renewables+nuclear fast enough so that our civilisation is not damaged too much by climate change. let's also assume we stabilised biodiversity and avoided a mass extinction. should we continue to produce massive amounts of energy so that some can commute by plane daily and others can stream cute kitten video in 8k?
    - deleted 4y ago
      [deleted]
    - usrusr 4y ago
- jackmott42 4y ago
  If you reframe it with solar panels it is just as troubling. Because then you need a massive amount of area for the panels.
dools 4y ago
I don’t think the goal is to keep flying as much, but to be able to fly at all. Also electrifying entire trucking and car fleets will take decades. This provides a means of producing an incredibly densely stored source of energy from abundant inputs, that is the same price as oil. It can solve for the problem of net zero production and transportation of equipment used in renewable energy production, for example, using present day transportation technology. There are no silver bullets, but all of these innovations add together in order to create a combined solution to the worlds energy problems.
- immmmmm 4y ago
  > There are no silver bullets, but all of these innovations add together in order to create a combined solution to the worlds energy problems. i worked all my professional carrer in science and innovation, if you have a reference for that statement i'd be glad you share it. maybe i missed something.
  - drpyser22 4y ago
    Do you mean that there is a silver bullet,or that innovations don't add together to provide solutions?
    - immmmmm 4y ago
      there's none. and (unfortunately for me) the best solutions often involve less technology rather than more.
  - smaddox 4y ago
    If fuel from air can be made efficient, then combined with highly economical fusion, I could see it being viable. I'm not sure it will ever be cost competitive with long tail oil and gas, though. And that's at least 30 years out.
    - pfdietz 4y ago
      > then combined with highly economical fusion If we had some ham, we could make ham and eggs, if we had some eggs. "Highly economical fusion" is probably an oxymoron.
bryanlarsen 4y ago
Or as their competitor puts it, we're going to need a lot of solar panels. https://terraformindustries.wordpress.com/2022/07/24/were-going-to-need-a-lot-of-solar-panels/ https://terraformindustries.wordpress.com/2022/07/24/were-go...
- immmmmm 4y ago
  a few dozen of km2 according to my napkin calculation. for one minuscule airport.
  - vagabund 4y ago
    The proliferation of solar farms is well underway and not abating with or without e-fuels, this just gives greater optionality to the energy they output and helps with intermittency. The land-use footprint of their tech as such is 100,000 gallons of car fuel per year per 'forge', each of which fits on a flatbed truck, plus a slated 5 manufacturing facilities to make the forges. That doesn't seem too bad. On the land-use of the solar panels themselves, I wonder if at some point in the future it might be possible to beam a directed laser to earth from space-based solar arrays, so the earth-based footprint is reduced.
paul 4y ago
Show your math. Unless those nukes are very small, your claim seems way off.
- tfussell 4y ago
  My back of the envelope calculation is that 1GW for 1 year is 30PJ. Jet fuel has 42MJ/kg with a density of 0.8 kg/L for a total of around 100 million liters of fuel at 100% efficiency. An A321 holds around 30000L which comes out to about 30000 flights equivalent from one reactor. GVA had around 200000 flights in 2018 meaning about 6 1GW reactors equivalent of fuel used (obviously not all flights would be fully loaded but I don't know what a normal load is).
- balfirevic 4y ago
  Another quick calculation, in addition to the one from tfussell: Google tells me [0] that total fuel consumption by commercial airlines in 2019 was 95 billion gallons. One gallon of fuel has around 33 kWh of energy. Power capacity needed to produce that amount of energy in a year is around 358 GW. Total world electricity production in 2020 was around 3000 GW-year [1]. [0] https://www.google.com/search?q=total+yearly+aircraft+fuel+usage https://www.google.com/search?q=total+yearly+aircraft+fuel+u... [1] https://www.google.com/search?q=total+world+electricity+production https://www.google.com/search?q=total+world+electricity+prod...
  - paul 4y ago
    Comparing global fuel consumption with global electricity production is a good approach. It’s clearly substantial, but doable, especially since fuel production can utilize “unreliable” renewables (make gas when the sun shines).
- sacred_numbers 4y ago
  According to this source [1] flights departing GVA generated 1.3 million tons of CO2 in 2018. According to this source [2], jet fuel generates 3.16 kg CO2 per kg of fuel. Multiplied by approximate fuel density and we get 2.57 kg CO2 per liter. We can therefore estimate that GVA consumes approximately 500 million (1.3 billion kg CO2/ 2.57 kg CO2 per liter) liters of fuel per year. Jet fuel contains about 35 MJ of energy per liter according to [3] so that's about 17.5 PJ. If the process to convert electricity to jet fuel is 50% efficient, that's 35 PJ. That is equivalent to a 1.1GW reactor running at 100% capacity. At the global average capacity factor of 80%, that's about 1.4GW required. Half a dozen is probably a pretty large overestimate. Alternatively, this would require around 6GW of solar, although 6GW of solar is probably quite a bit cheaper than 1.1 GW of nuclear power.
deleted 4y ago
[deleted]
ZeroGravitas 4y ago
In more traditional units: Prometheus can turn 77kwh of electrcity into 1 gallon of fuel. Jet plane with range of about 7000km has 52000 gallons so roughly 4GWh of electrical energy in to make the fuel, about half of which is lost as heat and the other half moves the plane. So the real question is, do you have a better use for that 4GWh of electrical energy? (Or more generally, and back to car size would you prefer 77Kwh of electricity or a gallon of fuel?) Carbon free electricity so cheap that you can make carbon containing fuels for less than fossil fuels is like a very heavy carbon tax in impact. Yes you can do whatever you like with the fuels, but since you pay directly for it, the market will respond by finding cheaper and more efficient ways to do the same thing, using the electricity directly or as a cheaper to convert fuel. Their pitch kind of makes sense for long distance flight, but unless it's a classic car that you only drive once a year, this fuel will have the exact same impact as a heavy carbon tax on the market for motor vehicles i.e. they'll be scrapped and replaced with EVs that are cheaper and cleaner to run.

steve76 4y ago

kaibee 4y ago

Solar is cheaper than nuclear and still getting cheaper, so looking at what you'd need in terms of nuclear reactors is likely to be misleading.

defterGoose 4y ago
I don't even want to think about how much surface area you'd need for solar panels intended to replace 6 megawatt-scale nuclear reactors, but I'm guessing football fields is the wrong unit to use... Last time I checked, land wasn't cheap and they weren't making any more of it.
- immmmmm 4y ago
  yeah and there's crop failure coming decades in advance compared to IPCC's predictions, so better not using crop space.
  - pwinnski 4y ago
    Some of that crop failure is due to heat, which could be mitigated by using solar panels to provide shade. That doesn't work for all crops, some of which require direct sun, but it works for more than I expected.
    - ncmncm 4y ago
      No crops require 100% direct sun. Maize and wheat yield is reduced a bit, without, but the year-round revenue from solar panels easily exceeds the difference.
- adgjlsfhk1 4y ago
  Land isn't cheap, but there's a lot of land that can have a solar panel on top of it without causing problems. A good place to start is every building roof.
  - pfdietz 4y ago
    Land is, in fact, cheap in very many places. If one were making fuel with the solar energy you wouldn't put the solar in places where land was expensive, since the fuel would be highly transportable.
- incrudible 4y ago
  > I don't even want to think about... I'd call that an argument from laziness. > Last time I checked, land wasn't cheap and they weren't making any more of it. Land that is remote, not fertile and that doesn't harbor any natural resources is actually rather cheap. Moreover, "they" are making more land in certain coastal areas where land is expensive.
- usrusr 4y ago
  Regarding land use, just yesterday I was pondering about what technology it would take to create survivable off shore solar. Some loose grid of floating collectors happily bouncing on the waves like a flock of resting seabirds, perhaps cleverly reeling in and out link and anchor lines to match the geometry of the waves? Or just the right amount of springyness, dynamically tuned to the wave situation? Then it occurred to me that even nature hasn't really solved ocean surface plants, what could be a more clear indicator that it's a really hard problem...
  - ncmncm 4y ago
    We have plenty of calm freshwater sites for solar, so there will be no need for ocean solar.
- Kon5ole 4y ago
  The correct unit to use is parking lots. If you base this unit on the current area used for parking in the USA, you can even use centi-parkinglots ;-)
- guiomie 4y ago
  SF Reservoir has 12 football fields worth of solar panels and generates 4.5 megawatts.
  - kaiwen1 4y ago
    It generates zero megawatts far more often than 4.5 megawatts. 4.5 is peak on the best days. 0 is assured for several hours every day.
    - guiomie 4y ago
      Thanks for added details. I was wondering if this project was efficient considering the amount of "fog" in this area.
- bluGill 4y ago
  When algee biofuels were first proposed someone calculated that Arizona could produce all the fuel we use on currently unused land. The limit is our ability to scale algee, but the lab results also show that the numbers are right.
- pfdietz 4y ago
  Yes, you didn't think about how much surface area, since if you did you'd realize it wasn't a big problem.
- adrianN 4y ago
  (I assume you mean GW not MW, because MW is very little for a proper power plant). Solar panels produce about 200Wp/sqm. In Germany they average to about 12% of peak production over a year, so say 22W/sqm averaged. 6GW continuous is then about 51k football fields[1]. I assume that the US has lots of land that is much sunnier than Germany, so you can probably get away with fewer football fields. [1] https://www.wolframalpha.com/input?i=%286GW%2F%2820W+per+square+meter%29%29+%2F+%28area+of+a++football+field%29 https://www.wolframalpha.com/input?i=%286GW%2F%2820W+per+squ...
nine_k 4y ago
What area would it take to produce several GW that a few reactors would produce? In clear weather, a surface perpendicular to the sunlight gets about 1 kW / m². So 1 GW would take a square kilometer. If our solar cells are top-notch 25% efficient cells, 1 GW will take 4 km² at best weather. And we need many multiples of that. Verily, Sahara must be the best place for such an oil factory. Maybe some of the US Midwest and West, with many sunny days. And, unlike the cute pictures on the side, they will need to be massive, all the way to the horizon. Maybe with a few nuclear plants thrown in if we learn to build them efficiently again.
- rootusrootus 4y ago
  > What area would it take to produce several GW that a few reactors would produce? Out of curiosity, I tried some napkin math on this. If Nevada went whole hog, used say, 1% of their total land for solar, they could produce almost half the electrical needs of the US, if I haven't mucked up the math too much. Sounds plausible, but 1% of Nevada's land for solar would indeed be 'all the way to the horizon' in many places.
  - ncmncm 4y ago
    That number is a bit low, but area for solar panels will never be in short supply, because the same land can be used as is used for other things.
- immmmmm 4y ago
  let's assume we can scale renewables+nuclear fast enough so that our civilisation is not damaged too much by climate change. let's also assume we stabilised biodiversity and avoided a mass extinction. should we continue to produce massive amounts of energy so that some can commute by plane daily and others can stream cute kitten video in 8k?
  - deleted 4y ago
    [deleted]
  - usrusr 4y ago
jackmott42 4y ago
If you reframe it with solar panels it is just as troubling. Because then you need a massive amount of area for the panels.

dools 4y ago

I don’t think the goal is to keep flying as much, but to be able to fly at all. Also electrifying entire trucking and car fleets will take decades. This provides a means of producing an incredibly densely stored source of energy from abundant inputs, that is the same price as oil. It can solve for the problem of net zero production and transportation of equipment used in renewable energy production, for example, using present day transportation technology. There are no silver bullets, but all of these innovations add together in order to create a combined solution to the worlds energy problems.

immmmmm 4y ago
> There are no silver bullets, but all of these innovations add together in order to create a combined solution to the worlds energy problems. i worked all my professional carrer in science and innovation, if you have a reference for that statement i'd be glad you share it. maybe i missed something.
- drpyser22 4y ago
  Do you mean that there is a silver bullet,or that innovations don't add together to provide solutions?
  - immmmmm 4y ago
    there's none. and (unfortunately for me) the best solutions often involve less technology rather than more.
- smaddox 4y ago
  If fuel from air can be made efficient, then combined with highly economical fusion, I could see it being viable. I'm not sure it will ever be cost competitive with long tail oil and gas, though. And that's at least 30 years out.
  - pfdietz 4y ago
    > then combined with highly economical fusion If we had some ham, we could make ham and eggs, if we had some eggs. "Highly economical fusion" is probably an oxymoron.

bryanlarsen 4y ago

Or as their competitor puts it, we're going to need a lot of solar panels. https://terraformindustries.wordpress.com/2022/07/24/were-going-to-need-a-lot-of-solar-panels/ https://terraformindustries.wordpress.com/2022/07/24/were-go...

immmmmm 4y ago
a few dozen of km2 according to my napkin calculation. for one minuscule airport.
- vagabund 4y ago
  The proliferation of solar farms is well underway and not abating with or without e-fuels, this just gives greater optionality to the energy they output and helps with intermittency. The land-use footprint of their tech as such is 100,000 gallons of car fuel per year per 'forge', each of which fits on a flatbed truck, plus a slated 5 manufacturing facilities to make the forges. That doesn't seem too bad. On the land-use of the solar panels themselves, I wonder if at some point in the future it might be possible to beam a directed laser to earth from space-based solar arrays, so the earth-based footprint is reduced.

paul 4y ago

Show your math. Unless those nukes are very small, your claim seems way off.

tfussell 4y ago
My back of the envelope calculation is that 1GW for 1 year is 30PJ. Jet fuel has 42MJ/kg with a density of 0.8 kg/L for a total of around 100 million liters of fuel at 100% efficiency. An A321 holds around 30000L which comes out to about 30000 flights equivalent from one reactor. GVA had around 200000 flights in 2018 meaning about 6 1GW reactors equivalent of fuel used (obviously not all flights would be fully loaded but I don't know what a normal load is).
balfirevic 4y ago
Another quick calculation, in addition to the one from tfussell: Google tells me [0] that total fuel consumption by commercial airlines in 2019 was 95 billion gallons. One gallon of fuel has around 33 kWh of energy. Power capacity needed to produce that amount of energy in a year is around 358 GW. Total world electricity production in 2020 was around 3000 GW-year [1]. [0] https://www.google.com/search?q=total+yearly+aircraft+fuel+usage https://www.google.com/search?q=total+yearly+aircraft+fuel+u... [1] https://www.google.com/search?q=total+world+electricity+production https://www.google.com/search?q=total+world+electricity+prod...
- paul 4y ago
  Comparing global fuel consumption with global electricity production is a good approach. It’s clearly substantial, but doable, especially since fuel production can utilize “unreliable” renewables (make gas when the sun shines).
sacred_numbers 4y ago
According to this source [1] flights departing GVA generated 1.3 million tons of CO2 in 2018. According to this source [2], jet fuel generates 3.16 kg CO2 per kg of fuel. Multiplied by approximate fuel density and we get 2.57 kg CO2 per liter. We can therefore estimate that GVA consumes approximately 500 million (1.3 billion kg CO2/ 2.57 kg CO2 per liter) liters of fuel per year. Jet fuel contains about 35 MJ of energy per liter according to [3] so that's about 17.5 PJ. If the process to convert electricity to jet fuel is 50% efficient, that's 35 PJ. That is equivalent to a 1.1GW reactor running at 100% capacity. At the global average capacity factor of 80%, that's about 1.4GW required. Half a dozen is probably a pretty large overestimate. Alternatively, this would require around 6GW of solar, although 6GW of solar is probably quite a bit cheaper than 1.1 GW of nuclear power.

deleted 4y ago

[deleted]

ZeroGravitas 4y ago

In more traditional units: Prometheus can turn 77kwh of electrcity into 1 gallon of fuel. Jet plane with range of about 7000km has 52000 gallons so roughly 4GWh of electrical energy in to make the fuel, about half of which is lost as heat and the other half moves the plane. So the real question is, do you have a better use for that 4GWh of electrical energy? (Or more generally, and back to car size would you prefer 77Kwh of electricity or a gallon of fuel?) Carbon free electricity so cheap that you can make carbon containing fuels for less than fossil fuels is like a very heavy carbon tax in impact. Yes you can do whatever you like with the fuels, but since you pay directly for it, the market will respond by finding cheaper and more efficient ways to do the same thing, using the electricity directly or as a cheaper to convert fuel. Their pitch kind of makes sense for long distance flight, but unless it's a classic car that you only drive once a year, this fuel will have the exact same impact as a heavy carbon tax on the market for motor vehicles i.e. they'll be scrapped and replaced with EVs that are cheaper and cleaner to run.