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Comment by ajmurmann | Hacker News Reader

This is super interesting! Sounds from the article like the main point is to remove CO2 from the air to improve air for humans. That's already really exciting. In essence it's a CO2 scrubber right? So how does this compare to devices built with the goal to remove CO2 with the goal to reduce climate change?

Edit: To answer my own question, this probably does little. They have a home use version that supposedly removes as much Co2 as twenty indoor plants. The paper linked below had three most efficient plant remove about 17% of Co2 in a cubic meter of air with optimal light conditions. So twenty of those wouldn't have much impact in a reasonably sized dwelling. That's assuming it's equivalent to the most efficient plant and great lighting. I cannot imagine the much larger installation at the airport making much of a difference either given the massive amount of air.

https://www.researchgate.net/publication/315968651_Effective...

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Good math.

Another way to ballpark this - the airport tank holds 500 liters of spirulina. Algae extract around 0.5kg co2 per 1000 liters ( https://mdpi-res.com/d_attachment/sustainability/sustainabil... ).

So this tank removes around 0.25kg of co2 per day.

By comparison, an average human exhales 1kg co2 per day. So you need four of those tanks to offset a single passenger passing by.

This does virtually nothing for the air freshness, and is possibly not even carbon negative if you were to count emissions from the device cleanup and algae storage.

Green washing at it’s finest.

Wouldn’t it offset one passengers CO2 for a whole day and not just a single passenger passing by? I’m sure that’s what you mean but the wording is a bit confusing.

It sounds like it would offset one person staying in the airport for a quarter of a day, yes. Though, with how many people pass through an airport, it means that this would do, instead of almost nothing, four times almost nothing.

Really it's about the average occupance of the airport over 24h, which is going to be far greater than 0.25.

I would assume the electricity used to power the pumps and lights ends up emitting substantially more than 250g of CO2 per day as well.

If only there was a large parcel of land nearby to an airport terminal where a renewable power source could be installed. Hmm, where could we find a large piece of relatively flat land with little to no trees to shade the sunlight? Hell, you could even cover the remote parking areas bringing extra value by providing covered parking and still leave the majority of that flat, cleared, open space unadulterated.

I’m guessing they don’t want to put stuff in the areas around runways, because that’s where planes go when something bad happens. I wouldn’t want to be escaping a plane directly into a chopped-up field of HV solar panels.

> By comparison, an average human exhales 1kg co2 per day. So you need four of those tanks to offset a single passenger passing by.

Passing by takes less then 24 hours.

"per day" is a rate and can be applied to any unit of time. 1kg per day is equivalent to 1/86400kg per second (1/(246060)). Math works out the same either way.

Someone must have missed the news stories of airlines preferring to cancel flights leaving travelers stranded in airports for extended periods of time.

Seems like 24 hours in an airport is becoming routine /s

And the PIT airport is under construction with passenger areas being replaced with removal of the mini-train. I hope they didn't pay for this green washing demonstration.

I feel like i would rather have the airport full of plants.

Airports are stresful and noisey. Imagine how calming it would be with greenery all over the place absorbing the noise.

They do not have to be noisy. Gardermoen is not noisy, Arlanda is not noisy, Copenhagen is not noisy. They just need to be designed deliberately to be quiet. Adding green plants won't make it much quieter unless you plant huge hedges indoors.

Yes, with garbage, ripped leaves, contraband stashed(people afraid and backing out), people hiding in bushes, bombs in the trees, and so on.

I guess it could be in some inaccessible way, greenery 20 feet up, or behind baracades with alarms.

But humanity is humanity, and part of airport security is probably the above.

(Also, according to a movie I watched, the next pandemic will come from plants, so we will have to kill them all, you see...)

None of that is likely to happen in the airports I occasionally visit.

Agree, I nevertheless bought one of their (AlgenAir) home devices, despite the fact that at present levels of efficiency I would need 100 of them to make a material difference in CO2 levels in a normal room. My thinking is that even given the incredible degree of efficiency of photosynthesis itself, there must be opportunities for other bioengineering-type improvements and 100x is not an unreasonable target over a 10-20 year timeframe. My dollars are an economic signal in support of investment in a machine to turn electricity into captured CO2.

That said, having had the device for a few months, it brings plenty of present value. It's pretty, a literal living lava lamp, and it makes a lovely water bubbly sound. Watching the algae population grow in concentration and change the color of the water is very satisfying.

For actual sunlight, where only 45% of the light is in the photosynthetically active wavelength range, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in a maximum overall photosynthetic efficiency of 3 to 6% of total solar radiation.

https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency

Thanks! Lots of room for engineered improvement!

Of the plants?

The irony is strong in this one: Not building airports would definitely improve the situation as a whole.

Of course, depopulating the earth will also accomplish that.

Or just building trains instead. Far lower energy consumption per distance travelled per person.

Trains are only viable regionally in the US, unless you want to spend 72 hours traveling for greater cost than a plane ticket that would have taken you 4ish hours to go from NY to LA. Even if we did build high speed rail the whole way, the number of stops along the way would only cut that to 24ish hours. Most people would choose the plane.

Look how many flights are from east coast city to east coast city. Just eliminating these would be massive.

But our rail system is outdated, our government won't allow realistic trains to be built. We don't need a million stops. We need metro to metro.

The east coast is large too. New York to Miami is over 1000 miles. People do take trains — it tends to be routes like NYC to DC or Boston, Philly to DC, etc.

The problem with any train system isn't the distance - it's the stops and slowdowns.

The fastest bullet train could make that (NYC - MIA) trip in less than 4 hours. (286 mph). That's great time. But once everyone adds a stop, and you have to slow down to a crawl through certain areas, and freight gets first pass, you can see why rail sucks in this country.

On land, it’d more like 1200 miles, so closer to 5 hours. Almost double the flight time.

I haven’t been to the US, but it can’t be all that special. Plenty of countries have high speed trains instead of most domestic air travel, even similarly sized ones like China.

Especially if you count the time to get to the airport and through security, high speed trains are highly competitive or even better than planes in total travel time.

The problem, as always, isn't size but density. Outside the east coast there is very little density. It's almost unfathomable having grown up in Europe how big and empty even large areas at the west coast are. This gets especially obvious when you get away from the central freeway that goes up the coast. Where I've visited our lived in Europe or Asia these areas would still be largely inhabited and have smaller towns sprinkled all over with small, frequently even walkable or bookkeeper distances between them. At the west coast, away from the freeway there is often nothing for miles and miles and then when you hit a small town is often partially abandoned. In other parts of the world these surrounding areas would provide passengers to the central transportation arteries via slow train and you'd have viable, slow trains transporting passengers to the major stops along the high speed track. None of that would be viable here. When the LA-SF highspeed train was planned they added stops in podunk towns to make it viable, IMO they were also removing any speed that would be comparable to airplane for any interesting connection.

And that's the west coast, once you go inland you'd maybe have one viable stop in most states of you want to keep it high-speed.

There are very sparse areas of China too, yet there are high speed trains between major cities across regions. Then there are additional slower lines with more stops from major cities to other nearby localities.

US coast-to-coast trains wouldn't need stops to be viable. They'd just need to initially be subsidised significantly, much like the current fossil-dominated industries are.

FYI: The Nozomi Shinkansen would take 13+ hours from NYC to LA at max speed if it was going on a straight line the entire time and completely ignore any constraints like mountains, etc. Even in this ideal scenario and it being subsidized to cost the same as an airplane ticket why would anyone choose the train?

The US is far less dense than China. China’s population is heavily concentrated on the eastern half of the country. The US has pockets of high density, spread all over the country, hundreds or thousands of miles apart. Major hubs include the Northeast, the Atlanta area, the Chicago area, the Texas triangle, Denver metro, Phoenix metro, SoCal, Bay Area, coastal Northwest, Miami.. building a HSR train network spanning the whole system would be massively expensive, and the density of the US makes it really hard to justify.

Bikes are even better! Yet bikes (with all the environmental cost of the metal mining, forging, production, shipping, plus replacement tires, brakes, and all the cost of air pressurized for the tires), are far worse than walking.

So we should all walk, yes?

But, I mean, the cost of shoes on the environment. They wear out quite fast, I walk 10 to 15km a day, and my shoes wear out every 3 to 4 months, so it makes more sense to go barefoot.

Yet again, the cost of all that food... food production is bad for the environment! Probably, I should not walk, or really go anywhere, and just sit still.

Right? Right?!

Here is the answer.

Don't suggest fewer plane trips. It will never happen, unless you purposefully hurt, and cause tyranny against others to enable your dream.

Instead, make a better plane. Make a better blimp.

Make people want your dream, instead of fighting your dream.

Make them love your solution, not your restrictions.

This is the way.

Nice argument. Except it's incredibly wrong.

Once recommended exercise thresholds are met, a durable bicycle is better than walking. Faired LEVs and light ebikes are better than bicycles. And full capacity mid speed (<200km/h) trains are better still. High speed rail is somewhere between walking and bicycles.

Maximise flourishing within a resource and energy budget. And if you invent a better plane or a lower impact energy source, add it to the menu. Do not blow the budget by an order of magnitude (or three) and then demand that technology fix the problem after the fact.

Trains are better than planes already. High speed trains are even exciting.

Ultimately, restrictions are necessary too. The frivolous per capita energy consumption in North America and Western Europe needs to be reduced.

Let me guess, you're the one that decides "frivolous"? I couldn't disagree more. Everyone needs way more energy. Most poverty is energy poverty and trying to reduce demand seems like a fool's errand. Electricity rules, stop pretending like it doesn't. We can figure out how to make more of it without destroying everything

That sort of thing needs to be democratically decided. Currently it isn’t, most countries have a few rich people dominating media and politics.

Most poverty isn’t energy poverty at all, it’s a lack of control over the means of production in general. Energy is merely one aspect.

Some energy usage is clearly frivolous, like several ton cars with single occupants or vastly oversized armies. Alternatives that achieve the same goals with vastly lower energy usage already exist and in some places are even widespread. Life can be different without being worse.

What you're describing is a dramatic reduction in human freedom. Right now I have the freedom to use as much energy as I can afford and people like you don't get any say in how I use it. Why not focus on generating more energy efficiently than imposing controls on other people? This seems like more about having control over other people than an actual concern for the environment or energy usage.

Would you vote to ban video games?

When lower energy alternatives are better and widespread, people use them. Why should we not strive for efficiency as a society?

I at no point argued for banning something, just offering better alternatives.

What do you think "democratic decisions" will do? You already hinted at banning certain types of vehicles you don't like. I'm wondering what other things other people enjoy you would like to ban?

You’re the one that keeps talking about banning things. I’d much prefer efficient and better alternatives were developed, which would convince people to use them.

Ultimately what you think is fun is irrelevant to whether it’s sustainable for us as a species. Just because a small minority of humans insist on having fun destructively doesn’t mean the rest of us shouldn’t be allowed to convince them otherwise.

You do realize putting democracy in front of something doesn't make it OK or even a good idea right?

Don't have to go that far. Choosing to not have children or choosing to have fewer children would be a good start.

From what I understand, taking better care of the children we have so they have a better chance to reach healthy adulthood is the best way to suppress child birth rates. I say we because parents don't own their children. The children belong to all of us, the community.

That thought is considered sacrilegious for some reason. If we would just start shrinking back to healthy population levels, a lot of problems would disappear. But nooo, an impossible reduction of everyones climate footprint by 10% is offset within 10 years of population growth instead.

One of the reasons that “overpopulation” as a concept faces criticism is that not all humans are created equal so far as resource consumption goes. Less people in the global north would do far more good for the climate than less people in the global south, because the former have a several times higher per capita consumption. Some of the people concerned about “overpopulation” seem to think the problem is the latter group though, and in that context the outcome of “depopulation” would be pleasing to fascists.

I live in the UK (and am in my late 20s), and I know quite a few people who are seriously considering not having children of their own (or in other cases reducing the number that thy would otherwise have) on the basis of overpopulation.

It's a mix of 'moral' feeling that you cannot tell people not to have kids, and of actual concern that our economic system is unfortunately founded on constant growth. It's much harder to grow the economy with fewer people.

This will cause serious problems and many developed countries and also in China, especially when combined with increasing life expectancies.

Isn't world population supposed to drop from now on?

If you believe world3 was correct, yes, we're nearing the decade where it happens, but this won't be by choice.

Basically our production+pollution seems to strain our renewable ressources more than our technological advances protect them. In most world3 scenarii it means a decrease in food production that lead to a population decrease.

It such a simple and interesting model, i find it sad that people tend to link it to 'the population bomb' which wasn't based on anything but gut feelings.

“Supposed” by whom? UN projections are peaking near 11 billion around 2100, IIRC.

Sort of. While increasing global CO2 levels makes it worse, indoor CO2 levels is mostly a function of buildings being made more and more efficient/air-tight. I live in a new LEED-platinum condo building, and in the fall or spring if I don't may my A/C unit on, my bedroom CO2 levels will go from ~500ppm to 1,300 or higher. You can see the drastic drop in CO2 levels when I wake up and open the door to get air flow.

actual chart of my room: https://imgur.com/a/zZRNQGX

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