Compost Toilets
Compost Toilets
I'm living on an urban farm half the week and I'm trying to build a compost toilet out there. Does anyone have an experience doing this? So far we're shitting in a bucket and throwing sawdust on it, but we're not sure how to compost the shit and haven't been brave enough to try anything yet. We also need to build a structure to enclose the toilet (right now we just have it semi-hidden on the property) so any suggestions on that would also be helpful. Ideally the structure is easy to construct, has an open roof but is tall enough that no one can see over the top and would be relatively easy to move/ tear down. Any suggestions on how to make the toilet lady friendly would also help... rn we are just 2 gross dudes shitting in buckets so...
Re: Compost Toilets
Thanks jacob. I actually just finished reading this book, it's very extensive which I like because 
. I hadn't seen the condensed version before, I was actually planning on making something like this for myself from the book so thanks for saving me the work.
Does anyone have any experience with success/ failure composting "humanure?"
. I hadn't seen the condensed version before, I was actually planning on making something like this for myself from the book so thanks for saving me the work.Does anyone have any experience with success/ failure composting "humanure?"
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Alphaville
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Re: Compost Toilets
lolol “2 gross dudes shitting in buckets”
my limited experience with composting toilets is they stink and are gross, but i gathered some info for a thread by @the animal which is in part about alaska and not freezing, but there’s stuff about microflush & using worms, etc:
viewtopic.php?p=205313#p205313
my limited experience with composting toilets is they stink and are gross, but i gathered some info for a thread by @the animal which is in part about alaska and not freezing, but there’s stuff about microflush & using worms, etc:
viewtopic.php?p=205313#p205313
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jacob
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Re: Compost Toilets
Not me, because city code ... otherwise, I really hate flushing all that fertilizer down the drain and eventually into the Gulf of Mexico.
However, IIRC one of the chapters in https://www.amazon.com/Being-Change-Spa ... 865718539/ talks about it.
However, IIRC one of the chapters in https://www.amazon.com/Being-Change-Spa ... 865718539/ talks about it.
of laws out there.Re: Compost Toilets
I’ve been shittin’ in a bucket for about two years now, and managed to snag a gf in the process.
What Jacob said. My experience:
-build a wooden box and put a toilet seat on it. I’ll post pictures of mine later. Don’t paint it white like I did. A buckets height is a little tall for most ladies, so build a little foot platform in front so people’s legs don’t swing.
-if it smells, moar sawdust/leaves/coconut coir. And/or pee less in it. It’s technically fine to pee in it from a composting perspective, but it gets swampy and gross fast, so you have to add a ton of sawdust. If lady company is occasional, let em pee in it. If lady company is often, maybe come up with a better plan.
-toilet paper technique: wipe, fold neatly, wipe, fold fold fold till it’s a compact little tp n shit nugget before dropping in the bucket. Similar to tp etiquette in places where you don’t flush tp. If you just wipe and drop, there’s a bunch of fluffy tp wads and you have to put extra sawdust to “cap” the turds.
-don’t just toss sawdust in there randomly. Cover the turds and done.
Actually composting requires a separate compost bin obviously. If your location isn’t arid, a couple pallets nailed together work fine. Get a bale of hay, or a bunch of leaves, and follow the instructions online for compost pile management. Don’t turn it!
-if you’re in an arid environment, you have to use something more air proof so it doesn’t try out. But I dont think that applies to you. This is my failure story, I built a pallet bin in the Mojave and the turds are all still perfectly preserved desiccated. I had to water it. Like with a garden hose. Like uncle Eddie. #lifegoals
I think if you keep the pile moist enough you’ll be good.
What Jacob said. My experience:
-build a wooden box and put a toilet seat on it. I’ll post pictures of mine later. Don’t paint it white like I did. A buckets height is a little tall for most ladies, so build a little foot platform in front so people’s legs don’t swing.
-if it smells, moar sawdust/leaves/coconut coir. And/or pee less in it. It’s technically fine to pee in it from a composting perspective, but it gets swampy and gross fast, so you have to add a ton of sawdust. If lady company is occasional, let em pee in it. If lady company is often, maybe come up with a better plan.
-toilet paper technique: wipe, fold neatly, wipe, fold fold fold till it’s a compact little tp n shit nugget before dropping in the bucket. Similar to tp etiquette in places where you don’t flush tp. If you just wipe and drop, there’s a bunch of fluffy tp wads and you have to put extra sawdust to “cap” the turds.
-don’t just toss sawdust in there randomly. Cover the turds and done.
Actually composting requires a separate compost bin obviously. If your location isn’t arid, a couple pallets nailed together work fine. Get a bale of hay, or a bunch of leaves, and follow the instructions online for compost pile management. Don’t turn it!
-if you’re in an arid environment, you have to use something more air proof so it doesn’t try out. But I dont think that applies to you. This is my failure story, I built a pallet bin in the Mojave and the turds are all still perfectly preserved desiccated. I had to water it. Like with a garden hose. Like uncle Eddie. #lifegoals
I think if you keep the pile moist enough you’ll be good.
Re: Compost Toilets
at my gf's place, they installed a judiciously placed funnel, which collects pee from male and female uretres due to its judicious placement. It appears to be the most effective way to avoid smell, because they don't smell, and every smelly dry toilet i use lacks this device. If you ask, I could post a picture.
Re: Compost Toilets
+1 to what Jean said. In Serenity, we use a half-gallon glass pee jug: I have an automotive oil fill funnel, DW uses an anatomically appropriate silicone thingy.
Inspirational pics (ah, there's the funnel):
Ammo cans (the shorter ones than the one in the pic) work well as a platform for the feet.
Inspirational pics (ah, there's the funnel):
Ammo cans (the shorter ones than the one in the pic) work well as a platform for the feet.
Re: Compost Toilets
@AH: Thanks for the advice and the pics. Aside from watering it (which we won't have to do because Louisiana) you don't treat the compost in any special way?
We've got a non-shit compost pile on the ground out there already. Do you think we should start a different one?
Do you think leaving it on the ground is alright or do we need a pallet/ something to elevate it?
How does the shit affect your ratio of brown (carbon/ leaves) to green (nitrogen/ food)?
Have you used your shit compost on food? This is obviously the goal since it's an urban farm, but we can also use it to fertilize non-food stuff and have another compost pile for food. My homie collects food scraps from local restaurants plus everything we make on the farm so we've got kind of a lot of compost material to work with.
Thanks again for the tips.
@Jean: Do you also have a compost toilet? Any tips on the composting process?
We've got a non-shit compost pile on the ground out there already. Do you think we should start a different one?
Do you think leaving it on the ground is alright or do we need a pallet/ something to elevate it?
How does the shit affect your ratio of brown (carbon/ leaves) to green (nitrogen/ food)?
Have you used your shit compost on food? This is obviously the goal since it's an urban farm, but we can also use it to fertilize non-food stuff and have another compost pile for food. My homie collects food scraps from local restaurants plus everything we make on the farm so we've got kind of a lot of compost material to work with.
Thanks again for the tips.
@Jean: Do you also have a compost toilet? Any tips on the composting process?
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Riggerjack
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Re: Compost Toilets
I don't know what other folks are doing, that they are worried about smell.
I've used indoor vented composting toilets, no odor that I noticed, but since I live in basically cold jungle, the draft wasn't pleasant. Think enclosed box as pictured above, with a 4" abs pipe venting outside. Close the lid, and gasses have other places to go.
I've used plenty of outhouses. Same approach, less waste handling. Traditionally, one would dig the hole, leaving a spoils pile for using as sawdust was recommended above. Other possible fillers would be wood ash from the firepit, or lye. Myself, I like ashes. As the hole fills, dig a new hole next to it, and move the outhouse over. Compositing in that hole is slow, but eventually you will have a nice fertile space for a perennial.
For making it GF friendly, one could go as simple as hanging a tarp from a wooden frame. This is the simplest/easiest/most temporary/concealable method. If I went that route, I would choose canvas painter's tarp. It's quiet in the breeze. Simple wooden rectangular frame, hinges to attach legs, and eye bolts in the top to attach tethers, then stake down the tethers. Breaking the shelter down would then just be similar to breaking down a tent. Additionally, toilet seats, a bench, an old fashioned chimneyed candleholder, TP and filler materials in separate old coffee cans with lids (damp does neither any good.)
The shelter frame would ideally have good hanging points for a solar shower, and perhaps a ground surface that can infiltrate water, but keep the mud down. Pavers work well if you aren't mobile, wood frames (pallets) if you are. If you go for something more permanent, a half light door and transparent roof panels let in lots of light, and that can be nice. Halfmoon's journal has some outhouse ideas...
Myself, I wouldn't use humanure on food (vegetables) crops. I would look at it as a good addition to compost added around trees, or other perennials. Or just add it to unused ground. The nutrients are useful, but the explanation to muggles is just too much dissonance for their minds to bear. The value of the nutrients is not high enough for me to set myself up for that level of potential hostility.
This is treading very close to an uncrossable line of sanitation, for those who know the least, and have the strongest opinions about sanitation. Unless spending your time and effort fighting the most deeply offended and ignorant, has some benefit to you, keep this on the down low.
Your planning dept knows how to resolve a neighbor complaint like this, it starts with a notice to cease activity, and leads up to daily fines, then land foreclosure/bulldozers/billing you for the bulldozing/local news stories about mishandling waste and public endangerment.
Here, in island county, in the center of ecotopia, composting toilets are legal, can be permitted, inspected and approved. Budget 5-10k, and you are good to go. (For reference, my entire 3br septic system including 400' of separation between tank and drain field and professional installation, cost me about 7k, ten years ago.) I don't know how louisiana deals with composting toilets, but if you need to, there are jurisdictions that have code for this.
It's not very ERE friendly to replace simple materials and skills with an expensive commercial product and the expensive certificate of approval, but it can be done, and in some places may be the best way to go.
Whatever you decide, post some pictures!
I've used indoor vented composting toilets, no odor that I noticed, but since I live in basically cold jungle, the draft wasn't pleasant. Think enclosed box as pictured above, with a 4" abs pipe venting outside. Close the lid, and gasses have other places to go.
I've used plenty of outhouses. Same approach, less waste handling. Traditionally, one would dig the hole, leaving a spoils pile for using as sawdust was recommended above. Other possible fillers would be wood ash from the firepit, or lye. Myself, I like ashes. As the hole fills, dig a new hole next to it, and move the outhouse over. Compositing in that hole is slow, but eventually you will have a nice fertile space for a perennial.
For making it GF friendly, one could go as simple as hanging a tarp from a wooden frame. This is the simplest/easiest/most temporary/concealable method. If I went that route, I would choose canvas painter's tarp. It's quiet in the breeze. Simple wooden rectangular frame, hinges to attach legs, and eye bolts in the top to attach tethers, then stake down the tethers. Breaking the shelter down would then just be similar to breaking down a tent. Additionally, toilet seats, a bench, an old fashioned chimneyed candleholder, TP and filler materials in separate old coffee cans with lids (damp does neither any good.)
The shelter frame would ideally have good hanging points for a solar shower, and perhaps a ground surface that can infiltrate water, but keep the mud down. Pavers work well if you aren't mobile, wood frames (pallets) if you are. If you go for something more permanent, a half light door and transparent roof panels let in lots of light, and that can be nice. Halfmoon's journal has some outhouse ideas...
Myself, I wouldn't use humanure on food (vegetables) crops. I would look at it as a good addition to compost added around trees, or other perennials. Or just add it to unused ground. The nutrients are useful, but the explanation to muggles is just too much dissonance for their minds to bear. The value of the nutrients is not high enough for me to set myself up for that level of potential hostility.
This is treading very close to an uncrossable line of sanitation, for those who know the least, and have the strongest opinions about sanitation. Unless spending your time and effort fighting the most deeply offended and ignorant, has some benefit to you, keep this on the down low.
Your planning dept knows how to resolve a neighbor complaint like this, it starts with a notice to cease activity, and leads up to daily fines, then land foreclosure/bulldozers/billing you for the bulldozing/local news stories about mishandling waste and public endangerment.
Here, in island county, in the center of ecotopia, composting toilets are legal, can be permitted, inspected and approved. Budget 5-10k, and you are good to go. (For reference, my entire 3br septic system including 400' of separation between tank and drain field and professional installation, cost me about 7k, ten years ago.) I don't know how louisiana deals with composting toilets, but if you need to, there are jurisdictions that have code for this.
It's not very ERE friendly to replace simple materials and skills with an expensive commercial product and the expensive certificate of approval, but it can be done, and in some places may be the best way to go.
Whatever you decide, post some pictures!
Re: Compost Toilets
Yeah if you're going to run a humanure situation in/near a farm, it's worth reading the humanure handbook in it's entirety. It's a brisk read.
+1 what Riggerjack said.
Run a separate humanure compost pile, don't add it to the normal one. If done correctly, it's claimed it's totally fine to add to food crops--but you're playing with fire re: legality and our fecophobic society.
Re: on ground or elevated: The humanure handbook will direct you to, once you've built your pallet bin: place at least ~6" of straw down on top of the ground, creating a "mat". Dump your bucket of poop in the middle of it. Pile straw on top of this and all around, so it's basically like an egg: yolk = poopwad, white = straw. For bucket number two, use a rake to pull back the straw on top of the poop, dump poop on top, and push straw "hat" back on. Add straw as necessary. You want worms and little bugs in the ground to be able to get up in to the pile, but you don't really want it "on" the ground directly. [PS Don't use that rake for anything else...]
I can't comment on brown/green ratio. If you're using appropriate fill material (leaves, sawdust, coco coir) and use straw in the pile, I got the sense you don't have to worry about it.
Don't treat the humanure with anything. (Some people add lye or etc to it to "cut down on the smell" in the toilet. Well that kills the bacteria. Bacteria is what composts shit! #facepalm)
Timing: build one humanure bin. Contribute to it for a year, or until it's full (as it composts it'll reduce in mass). Then build a second compost bin, and leave the first one alone for another full year. Just let it sit there. Then, at year 2, you can use that first pile, "fallow" the second pile, and re-start the first bin. Keep going back and forth every year. This method is just a way of making damn sure it's fully composted. You can also stick a thermometer in the pile when it's composting and should see it reach some "safe" temp (in the book).
That's all from memory from the book. I never got past "oh, hmm, it's WAY too dry here to run a pallet humanure bin", so I don't have experience actually running a successful pile for a year, fallowing it, and turning it. Someday. (Most of my toilet buckets get deposited in to very large catholes out in NF/BLM land, it's only when I'm near the family land that they go in the bin, which I'm not at consistently enough to "tend".)
+1 what Riggerjack said.
Run a separate humanure compost pile, don't add it to the normal one. If done correctly, it's claimed it's totally fine to add to food crops--but you're playing with fire re: legality and our fecophobic society.
Re: on ground or elevated: The humanure handbook will direct you to, once you've built your pallet bin: place at least ~6" of straw down on top of the ground, creating a "mat". Dump your bucket of poop in the middle of it. Pile straw on top of this and all around, so it's basically like an egg: yolk = poopwad, white = straw. For bucket number two, use a rake to pull back the straw on top of the poop, dump poop on top, and push straw "hat" back on. Add straw as necessary. You want worms and little bugs in the ground to be able to get up in to the pile, but you don't really want it "on" the ground directly. [PS Don't use that rake for anything else...]
I can't comment on brown/green ratio. If you're using appropriate fill material (leaves, sawdust, coco coir) and use straw in the pile, I got the sense you don't have to worry about it.
Don't treat the humanure with anything. (Some people add lye or etc to it to "cut down on the smell" in the toilet. Well that kills the bacteria. Bacteria is what composts shit! #facepalm)
Timing: build one humanure bin. Contribute to it for a year, or until it's full (as it composts it'll reduce in mass). Then build a second compost bin, and leave the first one alone for another full year. Just let it sit there. Then, at year 2, you can use that first pile, "fallow" the second pile, and re-start the first bin. Keep going back and forth every year. This method is just a way of making damn sure it's fully composted. You can also stick a thermometer in the pile when it's composting and should see it reach some "safe" temp (in the book).
That's all from memory from the book. I never got past "oh, hmm, it's WAY too dry here to run a pallet humanure bin", so I don't have experience actually running a successful pile for a year, fallowing it, and turning it. Someday. (Most of my toilet buckets get deposited in to very large catholes out in NF/BLM land, it's only when I'm near the family land that they go in the bin, which I'm not at consistently enough to "tend".)
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white belt
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Re: Compost Toilets
No firsthand experience with compost toilets, but here seems to be one pretty-detailed/well-researched setup: https://www.omick.net/composting_toilet ... toilet.htm
Also see here for Rob Greenfield's composting toilet setup: https://youtu.be/Hr5s0ps9rAQ?t=493
The barrel design for long term composting might work better in an urban environment instead of creating a separate compost pile.
I like the idea of a composting toilet, but it's not something I could implement at the moment since I'm living in small rentals. My other problem is I love my bidet toilet seat attachment and now can never go back to just toilet paper. As far as I can tell, a bidet won't really work with a compost toilet system because of the need to separate liquids and solids.
Also see here for Rob Greenfield's composting toilet setup: https://youtu.be/Hr5s0ps9rAQ?t=493
The barrel design for long term composting might work better in an urban environment instead of creating a separate compost pile.
I like the idea of a composting toilet, but it's not something I could implement at the moment since I'm living in small rentals. My other problem is I love my bidet toilet seat attachment and now can never go back to just toilet paper. As far as I can tell, a bidet won't really work with a compost toilet system because of the need to separate liquids and solids.
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white belt
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Re: Compost Toilets
Another option which may not strictly qualify as a compost toilet is using humanure as the input for a biogas setup. Again, I have no experience with it other than my own research.
The basic idea (in commercial product form) can be shown here: https://www.homebiogas.com/Products/HomeBiogas_Toilet
Youtube is filled with various DIY setups using barrels, tires, air mattresses, etc. See a simple one here: https://youtu.be/TA0l2EC77w8. Also check out Lucky Hill Farm youtube channel as he's done a lot of experiments with different DIY setups and compressing biogas to use for powering other things.
My understanding of the setup is as follows:
Inputs
-poop/pee
-food scraps (Rob Greenfield does this)
Outputs
-methane gas that can be used for cooking, heating, etc
-liquid fertilizer
The pros of this method seem to be that you do not need to separate liquid and solid waste. The cons are that the setup seem to be a bit more complex and space intensive than just a compost toilet. Additionally if you are using human waste as an input, you will have to figure out how to get that into your biogas fermenter. For the breakdown to occur, the bacteria prefer to be at warmer temperatures, but in New Orleans I imagine you should have no issues for 9-10 months out of the year.
What I don't understand is, how is this any different than just having a bag of raw sewage? I mean I guess the bacteria are breaking things down, but as others have pointed out, raw sewage can be quite dangerous.
To all the permaculture pros on here, what is your experience/opinion of biogas on a small scale?
The basic idea (in commercial product form) can be shown here: https://www.homebiogas.com/Products/HomeBiogas_Toilet
Youtube is filled with various DIY setups using barrels, tires, air mattresses, etc. See a simple one here: https://youtu.be/TA0l2EC77w8. Also check out Lucky Hill Farm youtube channel as he's done a lot of experiments with different DIY setups and compressing biogas to use for powering other things.
My understanding of the setup is as follows:
Inputs
-poop/pee
-food scraps (Rob Greenfield does this)
Outputs
-methane gas that can be used for cooking, heating, etc
-liquid fertilizer
The pros of this method seem to be that you do not need to separate liquid and solid waste. The cons are that the setup seem to be a bit more complex and space intensive than just a compost toilet. Additionally if you are using human waste as an input, you will have to figure out how to get that into your biogas fermenter. For the breakdown to occur, the bacteria prefer to be at warmer temperatures, but in New Orleans I imagine you should have no issues for 9-10 months out of the year.
What I don't understand is, how is this any different than just having a bag of raw sewage? I mean I guess the bacteria are breaking things down, but as others have pointed out, raw sewage can be quite dangerous.
To all the permaculture pros on here, what is your experience/opinion of biogas on a small scale?
Re: Compost Toilets
Thanks for the responses.
@RJ: I think you're right about the food. I don't think we need to worry about code violations because we are already violating so many. It's not a call the authorities type of neighborhood and my friend is good at maintaining good relations with the neighbors through being generally friendly, having a small plot that he grows that anyone can pick from and offering produce/ cooked food to neighbors.
However, he does sell food to restaurants and use the food for his own pop-up so. I can smell the headlines already.
Thanks for the structural suggestions, I'll discuss it with him after this hurricane and let y'all know what we decide.
Do we need to build an actual bin if we're doing humanure? We are just both so lazy. His current compost piles are on the ground covered by a tarp. He does also turn it, which is a no-no according to the humanure handbook.
Does anyone know if adding humanure change the ability to leave the pile on the ground and make turning the pile less of a good idea? Is it a bad idea for safety or compost efficiency reasons?
@RJ: I think you're right about the food. I don't think we need to worry about code violations because we are already violating so many. It's not a call the authorities type of neighborhood and my friend is good at maintaining good relations with the neighbors through being generally friendly, having a small plot that he grows that anyone can pick from and offering produce/ cooked food to neighbors.
However, he does sell food to restaurants and use the food for his own pop-up so. I can smell the headlines already.
Thanks for the structural suggestions, I'll discuss it with him after this hurricane and let y'all know what we decide.
Do we need to build an actual bin if we're doing humanure? We are just both so lazy. His current compost piles are on the ground covered by a tarp. He does also turn it, which is a no-no according to the humanure handbook.
Does anyone know if adding humanure change the ability to leave the pile on the ground and make turning the pile less of a good idea? Is it a bad idea for safety or compost efficiency reasons?
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jacob
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Re: Compost Toilets
Burying or sealing the humanure deters rats which otherwise find human shit kinda tasty. Ditto dog shit which is why it should always be picked up. Apparently not cow dung, though, which is why you can just pile up [cow] manure no problem. [Sealing it in] also prevents run-off when it rains. I know that some residences in the poorer areas in the US-SE just have their house sewer pipes discharge openly on the ground a bit further out in nature (like 30ft from the house) resulting in material problems with parasites like hookworm.
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Alphaville
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Re: Compost Toilets
kahneman in my brain today
friendly = system 1 = feels good, but invites disaster
code = system 2 = makes one frown, but is well thought out
eta: this seems well thought out: http://humanurehandbook.com/downloads/H ... l_2019.pdf
in a city prone to floods however, ymmv
friendly = system 1 = feels good, but invites disaster
code = system 2 = makes one frown, but is well thought out
eta: this seems well thought out: http://humanurehandbook.com/downloads/H ... l_2019.pdf
in a city prone to floods however, ymmv
Re: Compost Toilets
This thread is too many Wheaton Levels away from me...
Re: Compost Toilets
The compost process generates heat. That heat is what kills the real bad stuff in human shit, that makes it safe. Turning the pile disrupts this process. (Is my understanding from the book).Jin+Guice wrote: ↑Mon Sep 14, 2020 9:56 amDo we need to build an actual bin if we're doing humanure? We are just both so lazy. His current compost piles are on the ground covered by a tarp. He does also turn it, which is a no-no according to the humanure handbook.
Does anyone know if adding humanure change the ability to leave the pile on the ground and make turning the pile less of a good idea? Is it a bad idea for safety or compost efficiency reasons?
If you can figure out a way to keep the shit-nugget wad in a cocoon of hay/leaves material without walls of any sort, I suppose it would work to not build anything. But... man, it's like three pallets and six screws. I drug my feet building mine, and then I did it in like 20 minutes. I feel like dealing with a wall-less humanure pile would be more work over time than doin' it right.
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white belt
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Re: Compost Toilets
Well I think OP got most of his questions answered so I'll be curious to hear the final decision he comes too.
I've done a lot more research on using humanure to create biogas. I was starting to wonder why I haven't heard more about it in the permaculture space, but I think part of it has to do with code restrictions with humanure that Jacob alluded too.
For any folks that are interested in biogas, here is what I've uncovered:
Pros
-Biogas digester will yield 5 minutes of a high heat cooking flame daily per person/dog that you have contributing manure (biogas is 50-60% methane, source)
-Another output is effluent to be used as fertilizer (unsure on quantities), however you probably want to have that draining underground to fertilize non-edible plants or collect it in a sealed barrel to sit for a long time (the temperatures in a digester are not high enough to kill all pathogens)
-A digester can process meat, fish, dairy, liquids, etc that may not be compostable with traditional methods
-You can create up to 2 hours of cooking fuel per day if you add 1.5 gallons of food scraps daily (this is based on a digester the size of Home Biogas system)
Cons
-Digester requires warm temperatures (55-95F, but you really want to aim for the high end for efficiency) (source)
-Storing biogas is possible, however it will take up a lot of space if it is not compressed
-To compress biogas, you would need to run it through a scrubbing process to remove the sulfides and oxygen and then use a compressor to pump it into a bottle
-Digester needs to be somewhat large and is not portable when it is full
I think there has been some research on using the digester as a passive heater in a greenhouse during winter months. Biogas can then be burned to further heat the greenhouse/digester. I think this could be useful in an semi off-grid camper/rv/tiny house, as it means you no longer have to deal with emptying a black tank or being connected to sewer hookups. I'm envisioning a DIY system similar to the HomeBiogas 2 toilet system, so you wouldn't have to actually handle any of the humanure. Put the digester in a greenhouse to take advantage of heat and then either store the extra fuel for later or use it to power a heater in the greenhouse. I'd have to do more research into whether the physics of that makes sense, but from early research it seems it does.
I think if you have access to a source of a lot of food scraps (restaurant?) or other manure then the biogas digester makes sense. If just using humanure, it probably isn't worth it at the individual/household level unless you just like the idea or you don't have another sewage option.
I've done a lot more research on using humanure to create biogas. I was starting to wonder why I haven't heard more about it in the permaculture space, but I think part of it has to do with code restrictions with humanure that Jacob alluded too.
For any folks that are interested in biogas, here is what I've uncovered:
Pros
-Biogas digester will yield 5 minutes of a high heat cooking flame daily per person/dog that you have contributing manure (biogas is 50-60% methane, source)
-Another output is effluent to be used as fertilizer (unsure on quantities), however you probably want to have that draining underground to fertilize non-edible plants or collect it in a sealed barrel to sit for a long time (the temperatures in a digester are not high enough to kill all pathogens)
-A digester can process meat, fish, dairy, liquids, etc that may not be compostable with traditional methods
-You can create up to 2 hours of cooking fuel per day if you add 1.5 gallons of food scraps daily (this is based on a digester the size of Home Biogas system)
Cons
-Digester requires warm temperatures (55-95F, but you really want to aim for the high end for efficiency) (source)
-Storing biogas is possible, however it will take up a lot of space if it is not compressed
-To compress biogas, you would need to run it through a scrubbing process to remove the sulfides and oxygen and then use a compressor to pump it into a bottle
-Digester needs to be somewhat large and is not portable when it is full
I think there has been some research on using the digester as a passive heater in a greenhouse during winter months. Biogas can then be burned to further heat the greenhouse/digester. I think this could be useful in an semi off-grid camper/rv/tiny house, as it means you no longer have to deal with emptying a black tank or being connected to sewer hookups. I'm envisioning a DIY system similar to the HomeBiogas 2 toilet system, so you wouldn't have to actually handle any of the humanure. Put the digester in a greenhouse to take advantage of heat and then either store the extra fuel for later or use it to power a heater in the greenhouse. I'd have to do more research into whether the physics of that makes sense, but from early research it seems it does.
I think if you have access to a source of a lot of food scraps (restaurant?) or other manure then the biogas digester makes sense. If just using humanure, it probably isn't worth it at the individual/household level unless you just like the idea or you don't have another sewage option.