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Comment by jfim | Hacker News Reader

We'd still need tens of thousands of these plants. From [0] it's mentioned that

> According to Andreas Sizmann, SOLAR-JET project coordinator at BHL, a solar reactor with a 1 km2 solar field could generate 20,000 L/d of kerosene, which could fly a large 300-body commercial airliner for about seven hours.

According to [1] there are about 10000 planes in the air at any moment (excluding private jets, military, and cargo planes):

> Back in 2017, FlightAware determined there to be an average of 9,728 commercial airplanes in the sky at any given time. Of course, that number fluctuates on a minute-by-minute basis, given that planes are nearly constantly taking off and landing.

Doing the math of 10000 × (24 ÷ 7) gives us 35285 of these one square kilometer plants, or about 12% of the area of the entire state of Nevada.

So it might be actually doable from a back of the envelope math analysis, but it'd be quite a big endeavor to scale a facility that large.

[0] https://www.thechemicalengineer.com/news/first-kerosene-made...

[1] https://www.travelandleisure.com/airlines-airports/number-of...

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Well if replacing the entire global jet fuel system requires more than a handful of factories, then I'm out. We'll carry on with the more than 12,000 multi-storey floating oil platforms that currently exist today that drill into the seabed instead.

Having said that, just tax the externalities, and use the money to replace fossil fuels where a) it's barely an inconvenience or an actual improvement and b) it actually saves money, and lives, like EVs, and heat pumps.

Carbon is fungible, the relentless focus on the hard to decorbanize sectors is just misdirection, by the time they are the only sources of fossil carbon left, they'll be simple to fix with the abundance of cheap renewable energy we've built and the money we've saved as a result.

Yeah it sounds difficult to do, so we shouldn't bother.

> Having said that, just tax the externalities

That policy would not produce green energy that would replace the existing energy that we're now using at a societal level, it would just stop economic growth as we now understand it (mostly meaning more stuff being made, among other things). Yours is a call for more global poverty, plain and simple, which comes with its share of externalities.

Case in point: make natural gas more expensive or harder to get a hold of -> price of fertilisers increases -> less agro stuff being produced -> a lot more people in the developing world getting under the extreme poverty threshold and, in the end, a lot more people dying.

I think we're on different sides of a weird political split.

We both want to help poor people in the developing world, but you're only interested in doing so if it involves giving money to fossil fuel interests.

Whereas, I believe (like basically all economists do) that increasing the price of fossil fuels would actually help the world, by increasing efficiency and incentivizing better alternatives, many of which are already better than the alternatives and a net win.

At least we can agree that we both want to help people, and we also agree that one of us is tragically misinformed and actively hurting the people they claim to be helping by promoting counterproductive actions.

Our only point of disagreement seems to be whether it's me that's accidentally hurting people by suggesting we burn less fossil fuels, or if it's you that's hurting people by advocating for burning more fossil fuels.

> We both want to help poor people in the developing world, but you're only interested in doing so if it involves giving money to fossil fuel interests.

No, it's a matter of physics, you can't produce more agro stuff without fertilisers, that's what the Green Revolution has been based on. There's nothing to be "tragically misinformed" about when it comes to this simple fact. You need more agro stuff in order to feed 8 billion people and counting.

> by increasing efficiency and incentivizing better alternatives,

How does that help with producing enough fertilisers? Do those "better alternatives" produce the same amount of agro stuff as fertilisers do? Do they produce it now? If the answers to any of those answers is "NO" then those economists will have the deaths of tens of millions of people on their conscience. Again, there's no politics in this, it's just how physics works, you need energy to produce energy (which is what fertilisers are, in a way), nice and fancy words just won't cut it.

Fertilizers aren't made from hydrocarbons, they extract hydrogen from hydrocarbons, venting the carbon as carbon dioxide, then use that hydrogen to make fertilizer.

If your big thing is fertilizers, then you'd want a really cheap way of making fertilizers, which some people do actually want and they think that Green Hydrogen is already cheaper for this when you include externalities.

And even if you're the kind of person that really can't cope with the idea that externalities are a thing and just want to pretend they don't, then they'll be so much cheaper when we scale them up, that they'll still be cheaper even if you ignore all the misery and death that those externalities cause.

https://www.yara.com/crop-nutrition/products-and-solutions/g...

Weirdly, you seem to already know this, since you added in that bit about "Do they produce it now?". Maybe you're not accidentally killing people because you're misinformed after all.

> Fertilizers aren't made from hydrocarbons, they extract hydrogen from hydrocarbons

Granted, I’m not a native English speaker, but this looks like a plain contradiction to me.

Again, and to re-iterate, fertilizers is not “my” thing, is not anyone’s in particular thing, in a political manner, because you keep mentioning politics, it’s our 8-billion people thing, without fertilizers we cannot feed us, without fertilizers many more of us will die.

You’re putting words into my mouth when it comes to externalities, I did acknowledge them, I was just saying that the externalities that you mentioned (presumably higher CO2 concentrations from using fossil fuels, granted, you didn’t get into much details) are different than the externalities that I explicitly mentioned, i.e. that putting taxes on things like natural gas will lead to increased mass poverty and hence to increased (mass) deaths.

And to end on a positive note, glad the getting fertilizers out of hydrogen is getting cheaper, that means we won’t need taxes on natural gas, the simple law of supply and demand will do its thing.

There are several fertilizers required to maintain current global agricultural productivity. Phosphate and potassium are mostly from mineral (mined) sources today, but the one that is captured from the air is nitrogen, and to be used by plants it must be reduced from N2 to NH3 (ammonia) at which point it can also be converted to NO3 (nitrate). Since the early 20th century this has been accomplished by the Bosch-Haber process which utilizes natural gas as the source of the hydrogen to convert N2 to NH3.

The point is that you can make H2 via the electrolysis of water at scale, eliminating the need for the natural gas, and feed that H2 into the existing Haber-Bosch plants. Since sunlight and water are available basically everywhere, this eliminates a lot of the geopolitical and supply chain problems that are currently plagueing countries around the world with respect to nitrogen fertilizers (mined fertilizers are another story, of course).

> The point is that you can make H2 via the electrolysis of water at scale

Perfect, so there's basically almost free money on the table for those wanting to invest in this.

And then we get to transportation costs, afaik we're nowhere close to getting hydrogen-powered vehicles into mass production. And transportation costs represent a big part of the final price of food in some of the poorest parts of the world, think Central Africa.

And then there are refrigeration prices, which might not sound cool as an industry but which bring enormous food-related benefits. Good luck with keeping the freezers on in the same Central Africa with the help of green energy only.

Again, this green energy policy that is forced on almost all our throats here in the West from top to down looks eerily similar to the Maoist policies from the Great Leap Forward period, I sense the same "you're not a true believer" vibe if one starts stating the obvious. I don't think that my opinion or the opinion of the majority of the populace as a whole will manage to change things, unfortunately, but these things need to be said.

> Perfect, so there's basically almost free money on the table for those wanting to invest in this.

This is true. Have you ever actually tried to take advantage of free money though, when there's a cartel of giant corporations currently profiting from it not being done?. Harder than it looks. For starters they can convince a lot of people that the free money doesn't even exist. And once you convince someone to publicly state opinions like "renewables are expensive" or "EVs are worse for the environment" humans have a real hard time accepting new information that contradicts their previous public pronouncements. But early Tesla (and other EV related) stockholders for example, got rewarded for their attention to physical reality.

I guess we'll need to wait to see how it turns out this time but "The global green hydrogen market size was valued at USD 0.3 Billion in 2020 and is projected to reach USD 9.8 Billion by 2028, growing at a CAGR of 54.7% from 2021 to 2028" so either we're going to make a lot of money, or waste a lot of money.

> And then we get to transportation costs, afaik we're nowhere close to getting hydrogen-powered vehicles into mass production.

Hydrogen powered vehicles are mostly less efficient than battery (and/or directly electrified) alternatives, so while better (which includes cheaper) than many current options, they're not going to be a big thing. But Hydrogen is and will be, just made with electricity not fossil fuels in future.

Appropriately, one of the advantages of green hydrogen derived fertilizers, is that you don't need to transport fossil gas around the world and then expend a lot of energy seperating it into hydrogen, you can just generate the hydrogen and then the ammonia basically anywhere you have access to sun and air. Places with no methane reserves, high transport costs, and lots of sunshine will be where the green ammonia S-curve starts its ascent.

The transport and production of fossil fuels is an absolutely astounding percentage of our current energy use. Half of all current global Hydrogen production is used in the desulpherisation of fossil fuels for example.

> Granted, I’m not a native English speaker, but this looks like a plain contradiction to me.

In the context of taxing carbon to prevent climate change, and you claiming that taxing it would prevent people from making enough fertilizer to feed the world leading to millions of unnecessary deaths you don't see why it's an important distinction that the carbon vented into the atmosphere today in their production is a waste product of an entirely optional process for making one of the input elements (hydrogen) that fertilizers are built from and not actually necessary, or even desirable, for the end result?

This is clearly political. You've been convinced by political people that it's just 'physics' and therefore not political, but you're wrong about both the physics and the politics.

Plus, even when finding out you're wrong about the physics, you're mostly happy that this means that we won't need regulation, rather than happy about avoiding the tens of millions of deaths you were worried about when you thought other people were being political about something.

Who convinced you regulations were a bad thing (even when 99% of economists support them as the best free market solution) and why is that not political? Or is that just physics too?

According to [1], 8,400,000 acres have been disturbed by surface coal mining in the United States. My calculations makes that almost 34,000 square kilometers disturbed by surface coal mining.

[1] https://www.gem.wiki/The_footprint_of_coal

While I am the last person to minimize how bad coal is compared to every other option, "disturbed" does not mean "blackened death, devoid of life" in most cases.

There are a lot of replanted strip-mined mountains. It's not good, but does revert to nature... mostly.

A strip mine is leaching enough chemicals to kill birds that land there

https://www.sltrib.com/news/nation-world/2020/04/13/montana-...

https://www.youtube.com/watch?v=qtlPTE-UmY4

That's a copper mine, and yes mercury occurs naturally in copper ores.

Yikes, that’s quite a bit of mental gymnastics you’re pulling there.

Coal mines are horrible when they’re open and the horrible once they’re closed, don’t believe the P.R.

Yes coal mines are horrible. However, reclaimed mines are not worse for the environment than literally replacing equivalent acreage with a blanket of monolithic fused-silicon solar collectors (under which, there is no environment).

My point is not that coal is good, it is that the acreage comparison is not good.

> under which, there is no environment

https://news.ycombinator.com/item?id=29217929

Also, if you put a solar panel on a roof of a building, there will still be a building underneath the solar panel. Many people live in them, they dont get obliterated just because they are underneath a solar panel.

The point was that land which used to be a Coal mine can be surprisingly green. To the extent that something we normally consider unquestioningly eco-friendly - like large arrays of solar power collectors - could have a more degraded local environment in their direct vicinity (though they are beneficial overall).

I don't think anyone's saying coal is good or solar is bad here.

> Yes coal mines are horrible. However, reclaimed mines are not worse for the environment than literally replacing equivalent acreage with a blanket of monolithic fused-silicon solar collectors (under which, there is no environment).

Citation very much needed.

For starters, assuming we're mining the coal in order to burn it, rather than just for rock collectors, then the pollution and waste from that activity alone is enough to make it worse than solar. Killing more people, and animals, and destroying more environment while also costing more money.

You claim you're not the kind of person to minimize how bad coal is, but that's exactly what you're doing.

We don't need to do what you're suggesting (there's plenty of sensible places to put solar PV) but even if we did I would be highly surprised if it was worse than coal mining.

No environment? These sheep would beg to differ: https://www.photovoltaik.eu/sites/default/files/styles/auror...

Ok, it's mostly done in photovoltaic plants (and has advantages for both sides, because it stops plants that could eventually overgrow the solar modules), but I don't think there's anything stopping solar collector plants from being used the same way...

Yes, if you choose to use twice the acreage, you can have half the panel density.

Thats just plain wrong. In this case the environment means grass + wild flowers + insects + birds eating insects + insects and fungus that lives in the soil. That all survives under the panels and is ok with some shade and cooling. In fact this is better for the soil than intensive agriculture. And all possible without reducing panel density.

Yes; but in some cases the shade provided by the solar panels can increase productivity of the land (e.g. better quality wool, crops that don't like full sun, or even to protect crops from excessive heat in these ever hotter days.

What about putting solar on those old coal mines?

Please read the facts about mountaintop removal.

Point taken.

The incredible scale of our existing fossil fuel infrastructure is pretty mind-boggling, though. Apparently there are 145,000 gas stations in the United States. If someone today proposed building out an energy infrastructure that required the construction of one hundred thousand sites that each hold thousands of gallons of combustible fuel, fed by a network of trucks and pipelines from a vast array of refineries, fed by tanker trucks, extraction and drilling sites all over the planet...they would be considered nuts.

The energy density for electric planes just isn't there. So we need to do something. Generating jet fuel from some carbon-neutral source is about the only sustainable path we have to keeping an airline industry going.

A few thousand of these sites would be almost nothing compared to what exists.

Yes, but there are way too many gas stations in most places – many intersections in suburban cities will have two or more gas stations at the corners, or across the street from each other. That's not due to necessity, that's just due to profit motive.

There's a place near where I live where there are two Shell gas stations right across the street from each other! [0]

[0] https://www.google.com/maps/search/hamilton+rd+I-70+shell+ga...

It seems unlikely that we'll be able to sustain the same level of air travel once we're no longer able to rely on cheap fossil fuels for it. I suspect air travel will get a lot more expensive and less common.

short flights might go electric

high-speed rail works perfectly (though there's an obvious chicken and egg problem, because setting up a new airport is relatively trivial compared to building HSR connections between points of interest, but networks effects do matter, if there's an already good network it makes sense to connect new cities)

and for long haul flights the convenience will still make a lot of people pay for it.

plus, if society wants to subsidize it, we could. (like the US already does for certain routes.)

> once we're no longer able to rely on cheap fossil fuels for it

Why would that happen?

The most likely outcome would be a ban on net new CO2 in the atmosphere, enforced by the army of any country that has insurance companies unwilling to pay for the destruction of half of any cities next to a coastline, a 15-m wall around the remainder, most of the agricultural lands too hot and dry to be used, and the bulk of the rest battered by weekly cat-6 hurricanes, a billion of climate refugees…

A lot of people are going to die of heat in the next month. That number will double every year until we address it decisively.

That’s not counting on eco-terrorism which will likely anticipate a lot of the reaction.

Is this sarcasm or do you actually believe all of that is going to happen?

Not the OP, but pretty sure it's not sarcasm. I'm not sure if all of that will happen, but I would suggest that on current trajectory at least the following is likely to happen:

- Sea level rises leading to widespread flooding of vulnerable cities (and some particularly low-lying island countries too).

- Severe droughts and water shortages in desertous areas. Some of which may not have been desertous before.

- General weather changes (both reduced rainfall and increased rainfall) leading to disruptions in food production supply chains.

All of which will likely lead to significant political pressure to mitigate further disruption.

Atmospheric science isn’t belief: unless we rapidly change energy, transport, and construction practices, most humans will face existential threats in the next five years to ten years one way or another. That part is not for debate.

A lot of activists and governments have started responding (banning ICE cars in 2025, 2030, and 2035). My belief is that most will have increasingly strict rules because they will see increasingly obvious droughts, heatwaves, and hurricanes—that’s the part where I’m less sure about.

There are people and politicians who are delusional, so anything can happen. I expect them to move and be more popular in areas where the consequence will be dire soon.

There are people who protest and see no change. Them, and people who lose everyone they care about in climate-related disasters, will most likely resort to violence: this has already started with people attaching themselves with concrete to a highway or deflating tires of SUVs in London. That group is organized and they don’t feel heard. That much has happened and I can testify that it’s not blaming down. I believe that this will lead to more violence, notably targeted assassinations.

> The most likely outcome

I'm not so sure about that

Well if we're to hit net-zero carbon emissions then we either need to not emit any long-term stored carbon or capture and store carbon from the atmosphere. The former is likely to be much cheaper than the latter.

Because it becomes uneconomical to extract and process? And of course, eventually it will run out if we don't stop using it first.

That's the question: why would it become uneconomical to extract and process?

https://www.worldometers.info/oil/

47 years of oil left given current reserve estimates, I'd bet my life there's a couple of centuries left at least

Interesting top 11:

    1  Venezuela       299,953,000,000  18.2%   sanctions/attempted coup
    2  Saudi Arabia    266,578,000,000  16.2%   strategic ally (petrodollar)
    3  Canada          170,863,000,000  10.4%   neighbour
    4  Iran            157,530,000,000  9.5%    sanctions/coup
    5  Iraq            143,069,000,000  8.7%    invaded
    6  Kuwait          101,500,000,000  6.1%    friendly relations
    7  U.A.E            97,800,000,000  5.9%    friendly relations
    8  Russia           80,000,000,000  4.8%    sanctions/global rival
    9  Libya            48,363,000,000  2.9%    bombed/destabilized
   10  Nigeria          37,070,000,000  2.2%    friendly?
   11  United States    35,230,000,000  2.1%    *ahem*

It will become uneconomical because making the same chemicals, or better replacements, with renewable energy will be cheaper:

https://www.enapter.com/newsroom/reaching-price-parity-of-gr...

Reserves are misleading. Because people only declare resources to be reserves that have had enough investment in them to be proven to some level.

See https://www.adamsmith.org/research/the-no-breakfast-fallacy for more background.

Sooner or later we have to price carbon externalities correctly, and fund development of offsets. It’ll be later of course, but it’s the rational course.

Restating your math slightly, how can 3.5 of these be funded by a carbon fee from ~365 flights a year over 20 years? Doesn’t seem like an impossible problem to think through and at least gives us a path to a renewable cycle.

My view is you should pay the cost of removing the carbon you emit. The market forces would then give a very strong incentive to both be much less carbon intensive as well as develop better co2 removal strategies.

As always you need to factor in both positive and negative externalities.

If you do that, the positive would still come out way way ahead. (And not it's not priced in already contrary to popular belief)

The reality is that we can't sustain a civilisation of 8billion people without fossil fuels. We should do what we can to find alternatives that are less pollutant and have higher energy density but for now that means fusion, thorium and traditional fission. But we still have to solve the materials issue and we still have to content with the fact that only 20% of our energy is based on electricity and any attempt at increasing that number will require lots of fossil fuel usage as you would have to replace all the machines out there.

We are going to be dependent on FF for a long long time.

> The reality is that we can't sustain a civilisation of 8billion people without fossil fuels. We should do what we can to find alternatives that are less pollutant and have higher energy density but for now that means fusion, thorium and traditional fission.

This is just a failure to understand how much sunlight there is and how fast solar panels are getting cheaper.

Just like Germany you mean?

Solar panels will neither solve our increasing energy need nor be a solution for any future civilization.

Energy is about density. There is a reason why solar panels needs to be spread over huge areas to capture the sun.

So no I am pretty aware of solar panels and more importantly i understand the physics.

How many oil wells/barrels/square kilometers are currently dedicated to producing the world's jet fuel needs?

Wow, the US has just under a million operating U.S. oil and natural gas wells? That number surprised me, I don't know what I expected but I wouldn't have guessed that many.

https://www.eia.gov/petroleum/wells/pdf/full_report.pdf

Couple of interesting to things to note:

Oil wells have super long useful lives (50+ years) but The majority only produce <15bbl/day due to decline curves (especially pronounced gor.

The footprint of a well pad is pretty small one they’re in production ~<1/4 - 1/2 /acre. Many modern well pads can have multiple wells (4/6/12) due to directional drilling, further increasing well count.

Well, we are the largest producer of oil in the world: https://en.wikipedia.org/wiki/List_of_countries_by_oil_produ...

About the same amount of land.

In North America alone, 30,000 square kilometers for all oil and gas[0].

For a rough approximation, the US produced 14% of oil in the world in 2021[1] and this guy on Quora[2] says that 12% of the world's oil and gas goes into aviation fuel.

[0] https://www.science.org/content/article/thirty-thousand-squa...

[1] https://en.wikipedia.org/wiki/List_of_countries_by_oil_produ...

[2] https://www.quora.com/What-percentage-of-the-world-s-crude-o...

That’s all oil and gas activity; jet fuel accounts for only a very small fraction of that.

Already pipelines running from those areas :-) maybe in the future can transport solar jet fuel instead?

It only really matters if any particular facility is profitable. If so, they’re will exist and supply some portion of the fuel. There isn’t any reason to think they need to supply all of it.

What kind of raw materials are needed to cover 35,285 square kilometers with solar panels?

"Solar panels" usually means solar cells. These are mirrors.

The vast bulk of air travel is either intranational (domestic flights) or intracontinental (as with Europe, Asia, and Africa). For both, a well-developed high-speed rail network competes exceptionally well.

Short-haul flights are comparatively less efficient than long-haul as the high-energy take-off portion represents a greater fraction of total flight time. Once airborne, aircraft are remarkably efficient --- rougly on par with (single-occupant) automobile travel on a per-kilometer basis. (On a unit-time basis, of course, consumption is roughly 10x greater, and the induced travel via the Jevons paradox from reduced costs is considerable.)

But developing high-speed rail networks within countries and contiguous continental regions substitutes for a huge fraction of air travel.

It might also offload a considerable amount of overnight / express cargo delivery which presently moves by plane. Cargo utilisation of HSR might balance out passenger travel patterns and allow flexible capacity response to boot.

But rail has issues of its own. The biggest may be the amount of land it takes up. While the rail lines are thin, they are very long. And if you want them to be high speed, you can't have cars crossing them. So they're very expensive to build and they require taking plenty of land out of circulation.

Curious fact I discovered a few years ago: land use by airports and railroads in the US is roughly the same.

Airports tend to be large sprawling regions of urban land. Rail tends to be linear.

I'm not sure that the comparison is entirely fair: rail accounts for a small fraction of total passenger travel (though commuter rail is a surprisingly large portion). However there's an astounding amount of freight rail.

It's also possible to dual-use land near rail, especially where it counts (urbanised regions), through elevated, trenched, or subway routing. Mind, even then there may be noise and vibration issues, so you'd probably want to keep rail at some distance from residential areas, though I hear airports may have similar issues as well.

Freight rail also has a history of very large switching yards in areas. Compare the CSX yards near Chicago Midway Airport. Net direct land use appears roughly comparable.

https://www.openstreetmap.org/search?query=41.7813916%2C%2D8...

Mind that other transport modes also have large land-use demands. Private automobiles command a third or more of all land in many cities through streets and parking.

Sure, Midway and the freight yards use about the same amount of space. The point is that the rail uses a thin strip between towns. And if a road is to cross it, you've got to build an underpass or an overpass. The topological challenges are big.

Of course you're right about dual use and adjacencies and everything. It's the land between the towns that really is the issue. The airplanes are up at 30,000 feet.

Yes, rail roads require rail roadways.

And aircraft generate carbon emissions and a heck of a lot of noise.

A bigger problem for rail in regions with strong private land-ownership regimes is that this cycle develops:

- Undeveloped area is unsuitable for settlement due to lack of transportation.

- Railroads are built providing transportation. Costs are low as land values are low. (Historically, land was often gifted to railroads as an incentive to build, with the bonus of getting into the land trade on the side.)

- Railroads facilitate settlement, commerce, and industry.

- Land values rise spectacularly.

- Building new trackage / routes becomes nonviable due to high land values induced by previous cycle of rail development.

The ribbon-of-land thing really is not an issue where that land has a low price, or where appropriation of land (by legal or other means) is an option. Yes, you've now got railroads tracking across the landscape, but relative to the volumes of cargo and passengers carried this really is a minor consideration.

What is a massive problem is where routes cannot be expanded due to subsequent increased land valuation. Unless there's planning in advance for this, the problem is extreme. The US has seen effectively no new major rail construction in about a century, with a very few exceptions for a few regional transit systems (e.g., SF Bay Area's BART, DC's Metro). Those have relied heavily on the tunneling/subway & viaduct/elevated trackage.

Thin strips of land between towns ... is a non-issue. That's cheap land, it's largely fungible (e.g., farming or pasture acreage, like substitutions can be made.

And what rail doesn't have is the massive noise impacts of airport approach and (far more) departure flight paths. For overall impact, see this article on noise in the Chicago area generally:

https://www.dnainfo.com/chicago/20170328/midway/chicagos-lou...

The maps show both Midway and O'Hare airports, as well as several smaller airports, freeways and possibly rail lines.

The site providing the maps has moved, this seems to be it: https://maps.dot.gov/BTS/NationalTransportationNoiseMap/

That shows data for road, rail, and air traffic, which can be viewed independently. There doesn't seem to be a way to link to a specific view, but if you zoom in on the Chicago are and compare rail, traffic, and aircraft noise, the relative impacts become clear.