this post was submitted on 29 Dec 2023
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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.