Injecting combustion products into the upper atmosphere is something we really need to study more.
I supported the Ozone Hole studies in the mid 80's, and we found CFCs destroyed a protective part of our atmosphere. That recovered over time, but there are some rogue manufacturers using CFCs again, and leaking massive quantities.
We know airborne nuclei like soot cause localized precipitation, so that does change weather (it's called cloud seeding.)
We really need to know more about the effect of rockets at high altitudes, and airliner jet engines at 30,000'.
I have a strong feeling airliners have a significant effect due to the volume of air traffic and how dirty burning jet fuel is.
To see how jet engines could have a significant effect, there are around 10,000 airliners worldwide, which are in the air more than 12 hours each per day typically.
The break in air travel due do corona virus is an excellent time to compare atmospheric samples before and after the pause.
The data does not support the common opinion that airplanes are terrible for the environment. Their total contribution to for example CO2 is tiny compared to industry and electricity generation.
Somehow the climate activists have decided to make a lot of noise about flying but it's mostly unfounded. They go as far as using very old models of planes in their calculations (e.g. a 737-400 model) and claiming that's the amount of CO2 per passenger of all air travel. While that model is out of use by the airline for at least 15 years already. It was designed in 1985.
So beware of the data and tricks like this when you're told flying is so bad for the environment.
I think the reason flying is so often vilified is because it represents a huge proportion of an individual's emissions.
The reason flying represented only 2.5% of global emissions is because most people never do it. There's a small subset of people, mainly in the West, who do the vast majority of flying.
As this BBC article makes clear, a return flight from London to San Francisco represents half the emissions of the average London resident. If you fly a couple of return long haul trips a year, they'll emit the same as everything else you do for the rest of the year.
Looking at old aircraft will make the figures seem worse, but it's not like new aircraft are an order of magnitude more efficient.
The best case budget airlines (high seat density and high seat utilisation) today get about 2.27L/100km for each seat. The 737-300 was about 3.46L/100km - so about 65% of what it used to be. Better for sure, but not "we've fixed the problem" better. I'm not sure to what extent those figures take into account changing seat density and utilisation.
The average London resident emits unusually low amounts of CO2. A 5,369 miles flight, which is extremely long, at ~100MPG = 54 gallons of fuel. A 30 MPG car driven 15,000 miles per year is 500 gallons of fuel.
A far more common round trip London to Paris flight is ~6 gallons of fuel. So, someone doing that every weekend is still using 38% less fuel per year is using our 15,000 mile driver.
Flying only emits 2.5% of global CO2 because it’s surprisingly efficient and most people don’t travel ultra long distances frequently. LA to London takes a ~10 hour travel day each way making it unappealing to do frequently.
15000 miles per year is 41 miles a day every day.
If we see it as a work commute (plus some grocery shopping on the way), it's about 56 miles a day. Is this realistic in UK?
(I can imagine it can be that bad in some parts of the US.)
The comment you’re replying to makes the case that location matters. It’s arguing against your comparison of total CO2 emissions before you even made that point, and you’re not responding to it, but attacking some imaginary bad argument nobody made.
Your argument is also entirely generic. There is nothing that isn’t “irrelevant in comparison to industry and electrical generation”. Of note, “industry” can be split into arbitrary parts that would all fail your standard of significance. Meat production produces “only a fraction of CO2”. Residential heating, likewise, “produces a fraction of CO2”, and so do lighting, consumer goods, or the entire shipping industry.
Following your logic, nothing really matters, nor can anything be done.
> Somehow the climate activists have decided to make a lot of noise about flying but it's mostly unfounded.
It’s an activity that’s visible to everyone, it’s a personal choice (in the way that power generation usually isn’t), and a lot of air travel is a luxury and a convenience (again, more so than electricity).
something that tends to annoy me about hydrogen fuels - people emphasize that the combustion product is water. okay .. so that step is clean.
but how was the hydrogen in the fuel cell produced in the first place? i guess it’s an energy consuming process that produces a decent level of pollution, whether it’s by electrolysis, heating of a chemical in the presence of a catalyst, etc.
That’s entirely the point of hydrogen fuel. The process of producing or using hydrogen does not pollute. You have decoupled pollution from energy storage.
Hydrocarbons pollute by their very nature. In order to have a carbon neutral hydrocarbon cycle you need an impractical number of CO2 capture facilities.
And to add to your comment, spelling it out in case it isn't obvious: you can also decouple pollution from energy production using photovoltaics, wind or hydro - and suddenly most of your power chain is clean (what remains dirty is manufacturing the power generator and power storage).
the electricity has to be generated somewhere. coal plants - pollution. hydropower plants - pollution. you might say hydropower plants don’t produce pollution, but it takes a lot of energy to build them and they pollute the environment with their mere existence, no more pristine nature.
yes indeed i am, because they are related. electrolysis utilizes electricity. hence the prefix electro-.
your point highlights my initial point about hydrogen fuel - ie we must look all the way up the chain and account for all polluting steps, instead of simply focusing on a single aspect.
The water itself is also a problem, in the stratosphere. I think this places an ultimate limit on the number of rocket launches at about 1 million Starship launches per year.
Elon Musk plans on refueling his rockets on Mars using locally produced methane. Using solar power, he'll create methane and liquid oxygen from CO2 and water. If he then burns the methane and liquid oxygen in a rocket engine you get your CO2 and water back. Thus the process is carbon neutral.
Before he does it on Mars he'll have to perfect it on Earth first. I hope he does more than that and starts using carbon neutral methane for all his Starship flights on Earth.
The article implies that rockets burn 100% of their fuel, which is an oversimplification for most thrusters. There's also a fair amount of residual fuel and oxidizer in the piping, at least part of which is dumped into the environment. While it isn't that scary for something like kerolox, it's a concern for hypergolics.
Actually, this is mentioned in the article, in the "HOW MUCH DO DIFFERENT ROCKETS EMIT?" section, and gets more into it in the linked raptor article[1]
> Although all rocket engines do run fuel rich for the right balance of heat management and performance, so there is likely going to be unburnt fuel expelled regardless of the cycle type, but much more when it is an open cycle engine.
I supported the Ozone Hole studies in the mid 80's, and we found CFCs destroyed a protective part of our atmosphere. That recovered over time, but there are some rogue manufacturers using CFCs again, and leaking massive quantities.
We know airborne nuclei like soot cause localized precipitation, so that does change weather (it's called cloud seeding.)
We really need to know more about the effect of rockets at high altitudes, and airliner jet engines at 30,000'.
I have a strong feeling airliners have a significant effect due to the volume of air traffic and how dirty burning jet fuel is.
To see how jet engines could have a significant effect, there are around 10,000 airliners worldwide, which are in the air more than 12 hours each per day typically.
The break in air travel due do corona virus is an excellent time to compare atmospheric samples before and after the pause.