this post was submitted on 29 Dec 2023
255 points (97.4% liked)
Technology
58303 readers
8 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Another stupid fuel idea. How many #2s do you need to fly from New York to Los Angeles? Probably a shitload...
But seriously, this is just another idiotic Idea. Yes, you can make fuel from a lot of sources, but neither the quantity is there, nor is this in any way efficient or cost-covering.
I once calculated that we would need to cover each and every square centimeter of agricultural area in my country with rapeseed plants without crop rotation to produce the bio-fuel that the jets in my country burn. And that does not even include the energy needed to plant it, harvest it, and process it.
Fun thing about calculations is that if you write them down you can pull them out and show it to people who are skeptic about your claims, like I am being right now of your claims.
I actually would if it had not been on the site that should not be named, and which has the most shitty search engine. Maybe I'll try Google, if my posts are still there.
That's a lot of Canola oil!
Your claimed calculation is very vague, I have to say I don't believe for a second you actually did that and it's laughable you're claiming you did
When someone tells me that they've noticed a fundamental flaw that all the leading minds in the field have not it does not lead me to think that the field itself is flawed rather the person I'm speaking to's understanding of it.
Of course we understand that it's not all going to come from one source but where there are waste products like stalks and leaves left over from food production, poo, algae, and etc it makes sense to work towards using all of those so we can transition away from the extracting oil and gas.
It is not that I had found a "fundamental flaw". Those eco-fuel things simply don't scale up to realistic levels, and the people who are behind it know that their small-scale experimental systems will never power the current level of aviation fuel demands.
Yes, human poo has some energy left. But it is way less than the same amount of fuel, I.e. you need several tons of poo to create a ton of fuel.
OK, lets have a look at this poo idea. Human faeces have an energy density of 8kJ/g. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1793018/#:~:text=As%20the%20energy%20content%20per,measurements%20of%20stool%20wet%20weight.
Aviation fuel has an energy density of 43.5kJ/g. Source: https://s2.smu.edu/propulsion/Pages/energyex.htm#:~:text=The%20energy%20density%20of%20aviation,about%20820%20kg%2Fm3.
So if it was possible to get a lossless conversion of human poo to aviation fuel, you would need more than five tons of poo to create one ton of fuel.
A 747 from NY to LA burns about 60 tons of fuel. Source: https://www.quora.com/How-much-fuel-is-needed-to-fly-a-Boeing-747-from-New-York-City-to-Los-Angeles#:~:text=New%20York%20to%20LA%20would,be%2016%2C716%20gallons%20of%20fuel.
So you would need over 300 tons of shit to power that flight - if the conversion was lossless. It most likely is way worse.
Now a human produces between 125 and 500g of faeces per day. Source: https://www.healthline.com/health/do-you-lose-weight-when-you-poop#how-much-does-it-weigh
So you would have to collect the days worth of shit of way over half a million people to power this flight. And all this - again - with a lossless conversion. The reality is probably more like a 10% conversion productivity, meaning you would need ten times the poo.
I leave the question if this technology is actually sustainable to the reader.
And yes, my calculation of rapeseed oil based fuel was similarly funded in facts.
And those numbers are for ONE flight. How many thousands of planes are in the air each day?
Exactly. Bio-fuels simply will not sustain aviation at current levels. The only way to solve this is to drastically reduce air travel down to sustainable levels. Which might be "rescue helicopters only" if push comes to shove.
If push comes to shove the rescue copters will take a back seat to the military. There is what should be, and what likely will be, and those things are often very different.
Well, the military is known to produce a lot of shit on their own, so their fuel supply should be safe, regardless of.
I mean I'm pretty sure a water treatment center can spare some shit for this test
This might actally power a few dozen flights a day nationwide. All the other ones will still have to rely on dead dinosaurs.
Yeah, screw every effort to get us away from dependency on fossil fuels, am I right?
No. I just expose that aviation at the current level simply is not sustainable in any way.
They’re going to install more bathrooms on the planes and serve mexican bean salsa at boarding. That way the fuel can be made in flight.