Half a croissant, on a plate, with a sign in front of it saying '50c'
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Cellulosic ethanol with help from hard radiation

Grind wastes and make fuel out of them.
  [vote for,

1. Cellulosic waste is gathered in a large tank. This could be agricultural waste, paper etc.

2. Water is added: preferably untreated wastewater for the nitrogen content / cheapness.

3. Fungi of appropriate type are added.

4. Mix is allowed to sit for a bit. Fungi grow, exude cellulases.

5. Hard radiation is shined thru tank. Everything dies (in the tank). Cellulases continue to work but now nothing eats the glucose liberated.

6. Yeast are added to tank. Glucose ferments.

7. Ethanol is distilled off the top of the tank.

8. Rinse; repeat.

bungston, Mar 01 2016

Mold reduction using radiation http://www.ncbi.nlm...gov/pubmed/22856582
[bungston, Mar 02 2016]


       I think your problems would start at point 5. When the fungi die, they will eventually lyse and spew out proteases and other crap that will destroy the cellulases. But I might be wrong. So, [+] for the use of hard radiation.
MaxwellBuchanan, Mar 01 2016

       If fungal cells could keep proteases inside them they would keep the cellulases inside too. They spew all that stuff out and then hope for the best. Which is why they worry so much about opportunistic bacteria making off with the fruits of their labors.
bungston, Mar 01 2016

       // Cellulases continue to work //   

       Ionizing radiation kills cells by de-naturing proteins (amongst other effects) so enough radiation to reliably kill all the fungus culture is going to give the enzymes a fair battering too. Just one photon smacking into an enzyme is going to comromise its structure.   

       Radiation-sterilized food can still contain dangerous levels of organic toxins - seafood is a prime example. The product can pass bacteriological testing but still cause severe illness. But if enough radiation is used, the toxin can be significantly degraded too.
8th of 7, Mar 01 2016

       And after enough nutritionally-suspicious irradiated food is consumed, in addition to the residual organic toxins still in the food [thank you, 8th], bingo!, no more consumers requiring murderously-derived ethanol for cars, to drive to purchase more irradiated dead food!   

       I like how this reapportions the bioenergy; Revenge of the Sacrificed Fungi!
Sgt Teacup, Mar 01 2016

       Is it time to mention Soylent Green yet ?
8th of 7, Mar 01 2016

       Make the irradiated consumers into the irradiated food--brilliant! I was thinking of your shrimp example, but hey, why not think big?!
Sgt Teacup, Mar 01 2016

       //Ionizing radiation kills cells by de-naturing proteins (amongst other effects) so enough radiation to reliably kill all the fungus culture is going to give the enzymes a fair battering too.//   

       Well, not really. Yes, there will be some protein damage, but you can kill things with radiation doses that don't damage proteins enough to matter. What kills the cell is the amount of DNA damage, which overwhelms the repair mechanisms and isn't fixed before the cell wants to replicate again.   

       Also, considering that we humans are perfectly happy to eat food which has been incubated for prolonged periods at temperatures exceeding 100°C (causing utterly stupefying levels of chemical alteration), it's probably just childish to worry about the effect of irradiation.   

       But back to the idea.   

       Using radiation to kill the yeast is a bad idea, because it will be vastly expensive (even more so if you want to do it safely and legally). A much simpler solution is to kill the fungi with heat; I would guess that 50°C would do it, and probably wouldn't denature the cellulases. If fungi-killing temperatures _do_ denature the cellulases, it would be fairly easy to engineer the fungi to produce more thermostable cellulases that would remain active after heat-killing the fungi.   

       But then again, again, it's probably simpler and cheaper just to add cellulases to the mix. More effective than fungi, simpler and faster. Cellulases are already produced on a vast scale for things like ageing denim.
MaxwellBuchanan, Mar 01 2016

       // if you want to do it safely and legally //   

       Assume we don't. Ever.
8th of 7, Mar 01 2016

       A diet rich in naturally-fermented foods (sauerkraut, kefir, kimchi, yogurt, cheese, small beer...), local fresh veg, and grass-fed or free-range (wild) meat is both healthier and more conducive to being a joyful human. Irradiated food loses taste, texture, and visual appeal. Just sayin'.
Sgt Teacup, Mar 01 2016

       I have had kefir. When does the joy happen?
MaxwellBuchanan, Mar 01 2016

       The joy normally within 24-48 hours of consumption, [MB]. Of course the, shall we say, more restricted or inhibited human may feel the joy only after 3 or 4 days.   

       Additional measures may be required. Consider a side of psyllium, speaking of cellulose.
Sgt Teacup, Mar 01 2016

       On the morrow. In the loo.
whatrock, Mar 01 2016

       //Consider a side of psyllium// I'm happy to consider it, as long as that's all it takes.
MaxwellBuchanan, Mar 01 2016

       //Consider a side of psyllium//   

       "a side of psyllium", not "psilocybin" then ? Psilocybin would be much more ... interesting.
8th of 7, Mar 02 2016

       Don't be psilly
MaxwellBuchanan, Mar 02 2016

       / Using radiation to kill the yeast is a bad idea, because it will be vastly expensive /   

       Radiation is chosen to avoid denaturing the cellulase. And also, we will not be killing yeast until the distillation step. We will be killing filamentous fungi present in the first step as these are the ones that can make cellulases. It is analogous to making malt: you let the barley sprout, make amylase, then kill the sprout so it will not eat the product of its amylase.   

       But is it more expensive to kill with radiation than with heat? Let us consider energy budgets only. Water soaks up a lot of heat. I thought about recapturing some of the energy used later in distilling off the ethanol by routing the cooling circuit thru a vat at an earlier stage that was ready to heat up. Using gamma radiation to kill sidesteps energy lost to heating water.   

       Let me see about some math and web-scavenged info. As approach the blackboard I worry about orders of magnitude.   

       1 gray (radiation energy) = 1 joule / kg. I found (linked) 4 kilogray of gamma radiation = 99% kill for aspergillus niger, here representing generic fungi. So that = 4000 joules for 99% kill of a kg of fungus. That should be 4 kilojoules.   

       I found a value of 2261 kilojoules to bring 1 liter (1kg) of water from 20 to 100C. Even 37% of that (20C to 50C) is a lot more than 4 kJ.   

       Considering costs purely as energy cost, it looks lots cheaper to kill with radiation than heat. Unless I have gotten the orders of magnitude wrong.   

       I am considering a postapocalyptic world, as I am wont. The gasoline has gotten stale. When our denim is looking youthful and we call Sigma to order cellulase, alien zombies chuckle into the phone. So in the BUNGCO compound we will be brewing our own fuel to power the gyrocopter and look for survivors (the nightly parties are getting boring).
bungston, Mar 02 2016

       // lots cheaper to kill with radiation than heat. //   

       Airburst nukes mostly kill by heat flash and blast.   

       // Unless I have gotten the orders of magnitude wrong. //   

8th of 7, Mar 02 2016

       //Airburst nukes mostly kill by heat flash and blast. //   

       For ground-detonating weapons, it would be really, really unlucky to be killed simply by having the thing land on your head.
MaxwellBuchanan, Mar 02 2016


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