Biogas Resources

[minimutly]

The Nepalese have one advantage over us here when it comes to cow poo - it’s generally drier there, for most of the year. Water in the feedstock is a huge issue, so factor in a dewatering plant, and somewhere to get rid of the liquors.
So, you need poo, dryish poo. A boiler and pipe work within the digestor to heat it up. A way of pumping the gas into a bag or bell. If heats all your after just have a changeover from propane or natural gas to methane. If you have enough to generate a kW or so get a spark engine and generator, use the engine cooling to heat the poo.
How will you fill the digestor without losing the gas?

So, gas methane - it goes bang! Needs all kinds of safety systems etc. I used to work on large versions of these things once upon a time - really interesting, but smelly, with comprehensive safe working systems you had to follow. Two guys got killed near Bristol a couple of years ago despite this...

 

[addjunkie]

So, gas methane - it goes bang! Needs all kinds of safety systems etc. I used to work on large versions of these things once upon a time - really interesting, but smelly, with comprehensive safe working systems you had to follow. Two guys got killed near Bristol a couple of years ago despite this...

land fill sites do this on a small scale, the composting process generates heat that will kill bacteria, so a bio gas system would I assume be similar.

Ive only ever seen one, on a big estate up in Nicola country, but there were lots of very expensive bits of kit to tick all the safe boxes. Equipment that is suitable for flammable gasses is expensive to all not just the petro chemical industries.

 

[gaz1]

if the posters dont mind me posting videos on this post i can add further to this

so for heating purposes you can use compost as it gives off 100f-160f heat
straw bale walls range from R-17 to R-54

video is used as info

the issue is how to drain off that heat and be able to use a tractor

this video shows 3 systems that uses compost for heat to the biogas units and then through a filtration system

the main point is insulating the concrete bay area tech has changed enough and concrete can be well and truly insulated

this pdf is for the above video

https://www.nswai.org/docs/Heat%20Recovery%20from%20Compost.pdf

 

[slim_boy_fat]

I may have to walk back up there in a minute to check if they've a hill!

Any excuse!

 

[6ply]

@ Parm may have some input re h&s
Was reading something a couple of days ago that there has been a big safety problem even with smallish systems
Think a couple of large ones told improve or shut, may have been in the Times think there was an accident that started the purge

A very long time ago I had a "work experience" week at an aggregate extraction and landfill company. Part of the job involved site visits to check gas emissions. I recall it being mentioned that high gas concentrations were quite safe, the problem arose when there was a mixture of gas and air, a potentially explosive mix.

 

[daleyd]

A very long time ago I had a "work experience" week at an aggregate extraction and landfill company. Part of the job involved site visits to check gas emissions. I recall it being mentioned that high gas concentrations were quite safe, the problem arose when there was a mixture of gas and air, a potentially explosive mix.

Gas will only “explode” when mixed with air in a ratio between the lower explosive limit (LEL) and the upper explosive limit (UEL). I used to work mainly with industrial dryers and all our exhaust fans taking solvent laden air away were controlled by redundant systems which checked each other and ensured the volume was enough so that the maximum concentration allowed was around 1/4 of the LEL. This assumed that the machines feeding into the dryer were only able to dose at a certain rate, so if an operator decided to throw solvent over what was going in in an uncontrolled manner it could turn into a bomb

We did some fancy ones that had a flammability monitor (hydrogen flame, and a very accurate instrument that measured the temperature rise) which were allowed to be nearer 1/2 the LEL - we were then able to use some of the solvent filled air as fuel, but those were horrendously complicated and finicky machines.

For most processes you will always try to keep it below the LEL as it’s easier to control, if it gets to the UEL it is also safe but it’s harder to keep the levels up, ie keep air out.

 

[m_c]

if the posters dont mind me posting videos on this post i can add further to this

so for heating purposes you can use compost as it gives off 100f-160f heat
straw bale walls range from R-17 to R-54

video is used as info

the issue is how to drain off that heat and be able to use a tractor

this video shows 3 systems that uses compost for heat to the biogas units and then through a filtration system

the main point is insulating the concrete bay area tech has changed enough and concrete can be well and truly insulated

this pdf is for the above video

https://www.nswai.org/docs/Heat%20Recovery%20from%20Compost.pdf

The issue with composting heat recovery, is the economics don't add up.
I know somebody who looks into what is actually achievable with these kind of things, and anything involving compost just doesn't stack up for your typical farm operation.

Taking that paper above, they say you can get 1500btu/ton/hour, which works out to roughly 0.439kw.
Now take a small farm where they can possibly maintain a 10ton pile all year, so 0.439*24*365 = 4005KWh of energy.
We'll round down slightly to 4000, and at the current capped rate of 34p/KWh, gives an annual equivalent of £1360.
Off course, farms are probably paying above the price cap for electricity, but are more likely to have alternative fuel for heating which is likely to cost less.

Now if you're going to use pipe for that heat recovery, it'll cost you more than that in labour recovering/replacing that pipe in a year, given you'll be looking at 8-10 changes of compost.
If you're going to install a dedicated concrete bay, that's going to cost you multiple thousands for installation, and doesn't take into consideration any environmental issues that will also need dealt with such as run-off (dumping a pile of manure in the middle of a field avoids that issue).
There is also the need for the process to be continually monitored, as extract too much heat, and you kill the process.

As with all these things, it's all well posting about what's possible, but lots of things that are possible, just aren't practical.

And to use compost heat recovery to then feed in to a biogas system, is just adding an extra layer with potential to go wrong.

 

[Robotstar5]

We did some fancy ones that had a flammability monitor (hydrogen flame, and a very accurate instrument that measured the temperature rise) which were allowed to be nearer 1/2 the LEL - we were then able to use some of the solvent filled air as fuel, but those were horrendously complicated and finicky machines.

We used to have hydrocarbon detectors in the fuelling booths at JLR, if they went off it would put the building fire alarm into "warning" mode and activate the scavenge pumps to pull all fuel out of the building and back to the fuel farm. If the works fire brigade didn't disable the alarm within 8 minutes it would go into full alarm and it was everybody out time.

 

[minimutly]

A lot of private chp firms that would normally run on municipal waste have, at times of peak costs, imported onions and other crops - someone mentioned glycerine from biodiesel production. It’s a long way from a couple of blue barrels in the garden...

 

[Onoff]

So tell me, are all these hippy dippy YouTubers who post videos of compost heating or making biogas in the cheap talking BS?

 

[gaz1]

So tell me, are all these hippy dippy YouTubers who post videos of compost heating or making biogas in the cheap talking BS?

no its the usual you cant do it attitude

it makes me wonder sometimes how we invented stuff with the you cant do it of attitude that goes on

industry dosnt want you to do it not even small scale

 

[m_c]

So tell me, are all these hippy dippy YouTubers who post videos of compost heating or making biogas in the cheap talking BS?

They're not talking BS, it's just that they're only giving you part of the picture.
The processes work, but as per my last post, whether they're actually worth the effort is an entirely different matter.

 

[Erie Fred]

The Mother Earth News magazine used to have a couple of articles on them, one from India, Mr. Ran bux singh (IIRC)
and one was a different way, a french man using wood chips (he modified his hammer mill to make the proper chips)

 

[Onoff]

a french man using wood chips

Jean Pain?

 

[minimutly]

They're not talking BS, it's just that they're only giving you part of the picture.
The processes work, but as per my last post, whether they're actually worth the effort is an entirely different matter.

This indeed. It can be done, you could do it, but is the effort and cost worth it, especially if you’re one of the types that also has to work for a living, and doesn’t have all day everyday to fiddle with it.

 

[gaz1]

Now if you're going to use pipe for that heat recovery, it'll cost you more than that in labour recovering/replacing that pipe in a year, given you'll be looking at 8-10 changes of compost.
If you're going to install a dedicated concrete bay, that's going to cost you multiple thousands for installation, and doesn't take into consideration any environmental issues that will also need dealt with such as run-off (dumping a pile of manure in the middle of a field avoids that issue).
There is also the need for the process to be continually monitored, as extract too much heat, and you kill the process.

As with all these things, it's all well posting about what's possible, but lots of things that are possible, just aren't practical.

And to use compost heat recovery to then feed in to a biogas system, is just adding an extra layer with potential to go wrong.

well i could say

i dont want to smell your manure muck spreading over a few weeks over your fields

same as the manure dumped in a field

you have no right to stink an area out so you should be shut down for it whilst the comment might seem unfair

it would be the same as the manure pile that has gone wrong

it would cost you farmers thousands of pounds if you suddenly got fined for the smell going onto peoples clothes and in there homes because the farmers wont treat it first

i speak from experience as i live near the fields the smell is horid for a month and all depends on which way that wind is blowing

 

[addjunkie]

well i could say

i dont want to smell your manure muck spreading over a few weeks over your fields

same as the manure dumped in a field

you have no right to stink an area out so you should be shut down for it whilst the comment might seem unfair

it would be the same as the manure pile that has gone wrong

it would cost you farmers thousands of pounds if you suddenly got fined for the smell going onto peoples clothes and in there homes because the farmers wont treat it first

i speak from experience as i live near the fields the smell is horid for a month and all depends on which way that wind is blowing

It also depends whats been dumped and spread.

But dont forget, everytime you fine a farmer for a smell, your shooting yourself in the foot, as when his costs go up, your food prices rise too!
And said fields would have been having manure composted and spread way before your house was built.

The smells not normally for a month either.

 

[gaz1]

It also depends whats been dumped and spread.

But dont forget, everytime you fine a farmer for a smell, your shooting yourself in the foot, as when his costs go up, your food prices rise too!
And said fields would have been having manure composted and spread way before your house was built.

The smells not normally for a month either.

fine away for me they grow nothing

i wouldnt be bothered if they was growing in the fields, there not havent done in years

its not a 4 or 6 year cycle its been a 30 year + cycle of nothing in the fields only cow manure and pig manure in slurry

as it goes for food we import more from abroad all the big chains are from abroad so aint going to affect the price of food thats for sure

 

[addjunkie]

fine away for me they grow nothing

i wouldnt be bothered if they was growing in the fields, there not havent done in years

its not a 4 or 6 year cycle its been a 30 year + cycle of nothing in the fields only cow manure and pig manure in slurry

as it goes for food we import more from abroad all the big chains are from abroad so aint going to affect the price of food thats for sure

Do they not take a grass crop off it?

A very NIMBY attitude you seem to have!