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Comment by purplerhino | Hacker News Reader

What are the environmental implications of transitioning people traveling by car/train to small planes? In addition to being louder and dispersing pollutants over a wider area, don't small planes generate significantly more GHG emissions than cars over the same number of miles?

Also, given that planes are not nearly as easy to electrify as cars and trains (energy density is significantly lower in batteries than liquid fuel), it seems unlikely the planet will ever be able to support significant volumes of personal air transit. What are your thoughts on that?

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It's not just a question of whether they generate more GHG per mile, it's a question of whether they generate more GHG per hour. You wouldn't make a thousand mile trip over the weekend by car, but people don't bat an eye doing it by plane.

> You wouldn't make a thousand mile trip over the weekend by car, but people don't bat an eye doing it by plane.

You wouldn't take that by car? I would and I'm not an outlier in the midwest - many of us do it all the time. There just isn't a better option for a family. Flying would cost thousands of dollars more and you risk missing a connection and the trip taking even longer. The train doesn't really go many places in the US and isn't cheap. Just get in the car and travel on your own time - it is relaxing after a while. If you get bored stop to see some small town attraction for an hour and continue on.

Hard to tell. I have a frequent route that takes me ~ 2 hours of flight (13 liters/hour, 26 liters in total) or ~ 10 hours to drive with around 50 liters of gas. Flying means burning 50% less gas. But for others there may be better driving, how to calculate that?

What kind of plane are we talking about here? A Cessna 172 is cruising at about 200 km/h, so your route would be 400 km. You’re not driving 10h for that, right?

560 km, almost no highways, a lot of driving through the mountains at 50-60 km/h. Flying is an almost straight line of 320 km. Ikarus C42, cruising 160 km/h.

50% seems very unreasonable here, if not in the wrong direction overall.

Ikarus C42 at about 86 knots will use 13 L/hr, for a two-hour flight, it's 26 L fuel and 8.31 kg CO2/gal avgas[1], this comes to 57 kg CO2 to cover 320 km (and this is assuming it immediately starts covering flight distance and not using gas for climbing/approach, etc.).

An average new car in the EU uses 6 L/100 km in 2019[2]. To drive 320 km, this comes to 19 L of gasoline (8.1kg CO2/gallon finished motor gasoline[1]), which is then 41 kg CO2.

Even if you had to make the auto trip 400 km because roads aren't as direct, this comes to 51 kg CO2.

Nevermind that airports are rarely your final destination, nor in the city centre like train station would be, which adds significant distance to your overall trip.

[1] https://www.eia.gov/environment/emissions/co2_vol_mass.php [2] https://www.iea.org/articles/fuel-economy-in-the-european-un...

> Even if you had to make the auto trip 400 km because roads aren't as direct, this comes to 51 kg CO2.

What if there's a sogging great mountain range in the middle and I literally do need to drive 2-3x as far, because (rail) tunnels take something between 2 and 3 decades to build and won't be finished before 2040, if any are even planned to begin with?

That's exactly the case. Driving from Bucharest to Vatra Dornei, Romania. No highway yet, the one in construction (A7) is still going around the Carpathian mountains for 370km, it will make the drive faster but not shorter. Also driving highway speed takes more gas.

> driving highway speed takes more gas

Hmmm, in my experience, highway speeds are conducive to ICE efficiency and use less gas than city traffic stop and go results in. It also disperses pollution outside the areas people work/reside in.

There's three speed categories as far as the EU is concerned:

- highway

- not highway, not city

- city

The 90-110km/h limits of regular roads tends to hit the sweet spot of engines more reliably than the 130+ of highways, a lot of smaller European car engines are uncomfortably close to redlining at 130+, especially older ones.

Air resistance is not linear, which makes it difficult to be more efficient at higher speed, even if the engine is tuned for this.

In my personal experience with both my current and previous cars, the sweet spot is constant speed about 65 to 80kph.

It does feel slow though.

Then argue for convenience/speed/fun as I write here[1], not in the conversation about fuel usage. Even your example, driving from Bucharest to Vatra Dornei, RO is 490 km (DN12; 1.41x) or 520 km (DN2; 1.5x) vs 347 km, hardly 2-3x the parent comment you're responding to, again keeping in mind that the airport won't be in the middle of the city.

As for highway speeds, cars are calibrated to have the highest efficiency at highway speeds[2][3], so per distance, most cars will do best at reasonable highway speeds.

[1] https://news.ycombinator.com/item?id=41166749 [2] https://www.researchgate.net/figure/Speed-fuel-consumption-c... [3] https://qph.cf2.quoracdn.net/main-qimg-2ddbd8f31c84cefba540d...

You can always cherrypick examples that favour planes. In fact, to take it to the extreme, you can just put bodies of water in between and that might become practically the only choice as distances increase (e.g. there are no ferry service between Honolulu and Kona in Hawaii), and I'd agree with you in some cases planes are the most reasonable way to go between places.

That said, looking at the website for the main post, I don't think that's the main use case it has in mind: top banner rotating between "Flying made easy for first-time aviators/weekend trips/avoiding traffic" or "We believe the freedom of flying is an unparalleled experience that everyone deserves access to" and "The power of flight is intoxicating".

It's great if existing use cases of GA aircrafts have sleeker/more intuitive interfaces, but adding demand in this area (more hobbyists, more rich people using it for shuttling/avoiding traffic, encouraging people to live in very remote areas, etc.) and using it as transportation-mode will unlikely ever become environmentally reasonable.

Even a million additional GA airplanes used for leisure trips won't ruin the environment as much as cryprocurrency and AI does, so I'm not sure why HN of all places suddenly discovers their concern for environmental sustainability.

The solution for most people is not to have frequent trips to a destination that's 10 hours' driving distance or to use high speed rail. Comparing rocket fuel to airplane fuel may look one option look favorable but that's not the whole picture

It is not something I do for the fun of driving, it's my father's house and I need to help there. There is no high speed rail, train takes 9 hours too. As I said, there are situations and situations, cannot draw conclusions too fast.

There's a Swedish company working on making electric region air travel a thing - ahttps://heartaerospace.com

I don't see why this wouldn't be possible to do with smaller air craft.

Today, airplanes are not great when it comes to their environmental impacts. If we are successful in our bet that we can grow the GA market, we'll have the resources to invest into greener propulsion technology. That space is currently evolving quickly, with hybrid-electric, hydrogen, full electric and others all being explored. So it's in our plans to address that as well.

So your plan to reduce aircraft pollution is to… have more aircraft in the sky? Come on…

Innovation doesn't come from nowhere, and demand for air travel is not going away. So if there is a small, personal, innovative platform that makes it easier to test new propulsion technology at scale (in contrast to large commercial airliners that are less innovative), it seems entirely possible that could help with aircraft pollution in the long run

I'm sure that's what tobacco companies tell themselves also

There is also the option of not being part of the problem and finding a different job. Not an option for all employees, full ack on that, but this founder/ceo figure can absolutely make that choice

I see what you mean in that flying will always be something humanity does. We're not going to outlaw it, I have no illusions in that regard. Way too convenient and economically beneficial. Working on making it more accessible when we haven't made it even close to sustainable (with most of the solutions here today, it just needs to be scaled up and rolled out) instead of working on sustainability or alternatives to flying under a pretense of "it'll be better eventually!" is what I object to

Don't try to weasel your way out of this. Just be honest and say you like working on cool plane tech stuff and admit it's not great for the environment when more people will fly. No shame in that. Or maybe there is shame, but that's up to you.

maybe I wasn't clear but I completely agree that airplanes are not good for the environment. That absolutely needs to be fixed. But to fix it requires capital and public demand. We are hoping to generate both by getting more people flying so that it's not just a niche people who fly planes and care about the environment working asking for it and spending money in the industry

This is like saying that you know gas power plants are not good for the environment, so you're hoping to get gas generators into more homes to generate capital and demand to fix the problem.

If your company is successful enough for you to invest significant resources into "greener propulsion technology", what is going to happen to all the planes you already sold to get there? Are you going to send an email blast out to all your customers telling them to stop flying now because it's time to pivot to hydrogen planes?

Classic false equivalence. Mature airplane engine technology based on alternative energy really doesn't exsit at the moment, while the same cannot be said for residential energy.

The existence of the a fossil fuel based car market provided an impetus for electric car and battery technology to develop. Similarly, practical alternative energy flight will likely develop faster if there is a market for small, innovative aircrafts.

> airplanes are not good for the environment.

> to fix it requires capital and public demand.

In my engineering career, one thing I've learned is that if you fix problems B, C, and D, often it becomes a lot easier to fix orthogonal problem A, because the other fixes have made new things possible.

I see what you are doing as fixing a lot of problems with flying, so then more attention can go into making planes quieter and more energy efficient.

Perhaps yours is one of the steps to making planes as peaceful in the environment as birds[0].

[0] https://breckyunits.com/ifNatureIsDoingIt.html

This forum is providing me a rare opportunity to speak to someone of your caliber:

To someone not surrounded by the same aerospace/defence/pentagon welfare state people that you are surrounded by, you come across as very genuine, caring, and hard-working but completely missing the point. Your statements in this thread indicate that you think there maaaaay be an environmental issue but you don’t care because it could never affect you personally. You demonstrate no sense of urgency, which is what the people questioning you are looking for, because that’s what the science shows.

And you don't see the problem with your reasoning? Honestly not?

So, in order to reduce airplanes environmental impact, your plan is to increase it first by putting more airplanes in the sky?

Sounds like some wicked variation of Jevon's paradox.

Just wanted to say thanks for saving pilot lives and making an awesome sport more accessible. As someone with a background in controlling difficult vehicles who has seen the accessibility improvements of electric assists, your plan makes sense to me! And the plane is priced appealingly. Please don't feel discouraged by the loonies who can't do math deciding that today is the day yet another niche sport (0.04% of global emissions) must die at the altar of the Environment. They'll forget by tomorrow.

So you have no incentive to vote for a carbon tax

I didn't want to make a snarky, unabashadly NIMBY comment until I read this response. For every dollar you lower barrier to entry in aviation, I'm going to be calling my local government representatives to raise it back up by two with taxes and fees.

The solutions to environmental problems aren't to grow markets with technology we know is bad so we have the money to make it less bad. The solution is to make it so expensive for the average consumer that it's uneconomical to do the bad thing at all.

> I'm going to be calling my local government representatives to raise it back up by two with taxes and fees.

Sometimes I think this sort of approach is why so many people on the right are sick of global warming. Sure, global warming is a serious problem, but that doesn't mean that taxing things you don't like is wise, fair, effective, or in any other respect a good idea. If you have a problem with emission of gasses with global warming potential, do that, but please do it across the board.

Let's not specifically tax GA planes, ban gas water heaters, and do a bunch of other random minor-ish things that annoy people and don't actually target the problem.

Burning fossil fuels is the problem. We can argue until the cows come home about things like plastic straws and bags, but the fact is that burning fossil fuels is rapidly destroying the planet and no amount of burning is sustainable. Banning that is table stakes.

Proposing to ban burning fossil fuels entirely is a great way to get very little support for your proposal.

Hence the decades of inaction and even subterfuge to prevent action.

Don't talk about banning, talk about giving people a good alternate. Fix zoning so that people don't have to move so far out just to afford a nice place to live (people who want a hobby farm will have to live that far out, but many in the suburbs would be happy with a 5 bedroom apartment for a similar monthly costs - but none exist). Build good transit so that people have a reasonable option to driving.

If you want to ban fueles you just attack people's way of life. If you want to provide the things I list you don't need to ban fuel as they will switch to not driving.

I'll take the "ban fossil fuels" comments seriously when nuclear energy is back on the table.

Plane fuel does not have the same taxes than the fuel you use on your car.

Should car and plane fuel have the same tax level if used as personal transport?

Depends whether you think it’s reasonable for fuel tax to also price in road maintenance and local pollution along the route. Airplanes don’t make potholes in the sky, and the cruising portions of their routes don’t expose anyone to any appreciable concentration of particulate, NOx, etc emissions from planes.

Taxes on fuel are a way to deincentivize the use of private cars, at least in my country with the fuel tax you can't pay all the infrastructure cars use.

We already have prototype electric aircraft. As battery costs decrease and battery performance improves, it makes perfect sense that aircraft will electrify. The reason for this is economical, not environmental. Electricity is cheaper than fuel, and maintenance for electric vehicles tends to be less than their combustion equivalents. Both of these factors mean that once the batteries become cheap enough, cost per passenger mile will be lower.

If you decrease the potential market for a product, companies will put less R&D into those products. In the US, general aviation is less popular than horseback riding, which is why we're still using leaded gasoline and piston engines.

The laws of chemistry that govern batteries and fossil fuels are known very well. We will never get batteries anywhere near as light weight as a liquid fuel. Sure the battery/motor is much more efficient, but not anywhere close to enough to make up for the massive energy/weight advantage liquid fuels.

It's not about weight or efficiency. If operating costs are lower, it will win out eventually. Current electric aircraft can carry 5 passengers and have a range of 250 miles. They cost half as much to operate per hour, because electricity is so much cheaper than fuel. The main reason why they're not popular is because batteries are expensive. As battery costs decrease, we'll see more of the market adopt them.

Will electric aircraft cross oceans? Probably not. But the batteries are already good enough for useful flights. And you have advantages such as VTOL, quieter operation (allowing you to use urban airports at times when other aircraft are banned due to noise restrictions), and less maintenance.

250 miles isn't nearly as much as it sounds - you need to leave plenty of buffer in case something goes wrong so cut some of that off. You also need to get to an airport and then from the other airport to where you are going. Thus most of the time for distances of that range driving is faster.

The cases where I've seen this in use are from island to island (or mainland) - where a boat is much slower and there is no bridge for a car. A useful niche, but not general purpose getting around. There are also a few people who happen to live near (often on) an airport and work near an airport who will fly, but that is also a small niche.

The 250 mile range is with the buffer. Beta Technologies has flown their CX300 craft 386 miles on one charge.

Their planes cost half a million dollars, I’m not too concerned about everyone flying just yet. These are expensive toys for the wealthy.

So wrong. You can get an airplane for the cost of a car. Yes, it won't be new and it won't be fancy, but you can definitely fly without being wealthy.

So right. Look on the website, they say it’s half a million. I’m not talking about any plane, I’m talking about the subject of this thread.

I take it from your attitude that you don't drive, fly commercially, buy resource-intensive consumer goods, use electricity produced from nonrenewable sources, or eat food produced from large-scale agriculture then, and agree we should make those so expensive for the average consumer that it's uneconomical to do these bad things at all?

Because otherwise your comment sounds more like hypocrisy.

Perfect is the enemy of good. I fly on rare occasions and I'm against flying unnecessarily. I drive a vehicle (shared with partner) because I don't want to be a hermit, yet I'm against driving in general (of course there'll need to be exceptions for when you're moving or too old to walk to/from public transport) and rather in favor of building out the more sustainable alternatives we have already today. That's not the whole solution because we will still run out of lithium etc., but it's the best we can do today even if it's not perfect

Perfect is indeed the enemy of the good. So we should realize that not everyone values the same things and not single out something as deserving extinguishing just because it's something we personally don't value.

> not everyone values the same things

Pardon? We don't all value human lives? I'm not sure we're having the same conversation if your attitude to pollution is "that's just your opinion"

These things are objectively measurable. I don't even know where to begin, your comment is so odd to read idk if I'm misunderstanding you or what part of climate warming leading to all sorts of issues virtually everywhere, air pollution leading to health issues and premature deaths, the ongoing mass extinction that threatens our food system, etc. you're unaware of

Look, go ahead and increase fuel taxes. If you reduce car fuel consumption by just 1%, but this company succeeds and quintuples (!) the fuel consumption by piston engine planes, the environment still comes out ahead. Flying is a tiny environmental factor compared to driving.

[Avgas consumption in the US is about 200m gallons a year, car fuel consumption some 130,000m gallons. Car plus planes 130,200m. Car -1%, planes x5: 128,700 + 1000 = 129,700m gallons.]

> Flying is a tiny environmental factor compared to driving.

That's a common fallacy.

For example, i could say that the environmental impact of driving in my city is insignificant compared to the total. And that if you reduce emissions in others cities by just 1% in the rest of the world, but my citys emissions increase x5, the environment still come out ahead.

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