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Biomass gassification question.

Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
First off let me say I thank all of you for your help. I am fairly new to a lot of this and I know I ask a lot of questions. I am trying to self educate but I find that the more I learn, the more I need help filling in the gaps. I appreciate all of your patients with a new guy.

My question is about biomass gasification. I have seen it mentioned in several places so I went looking to read up on it and I understand the basic process of heating dry biomass to create syngas. Here is the gap I cant seem to find the answer to.

Lets say I build my house and I want to use a gas stove in the kitchen rather than a wood stove and I definitely want to save my electricity for other things. SO I'm going to run my cook stove on syngas made from biomass form the property.

In a home set up does the gas have to be used as it is being made or can it be stored in bulk like propane in a 500 gal tank for future use? I know propane is under pressure in liquid form when we use it for home use. Can the same or similar thing be done with syngas? Or would I have to go out and make a batch of gas every time we wanted to use the kitchen stove?

Watching some of Dan Rojas you tube videos leads me to beleive that if it can be stored, large batches could be made using a large Fresnel lens as a heat source on a sunny day.

Another question I have is just how labor intensive is this process? I mean are you expending $20 of labor to save $5 of LP gas for the stove?

Again thanks for your help and patience with a new guys many questions.

Ray
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
Ray Cover wrote:Lets say I build my house and I want to use a gas stove in the kitchen rather than a wood stove and I definitely want to save my electricity for other things. SO I'm going to run my cook stove on syngas made from biomass form the property.

In a home set up does the gas have to be used as it is being made or can it be stored in bulk like propane in a 500 gal tank for future use? I know propane is under pressure in liquid form when we use it for home use. Can the same or similar thing be done with syngas? Or would I have to go out and make a batch of gas every time we wanted to use the kitchen stove?


http://www.youtube.com/watch?v=0xmRWw9LWFw&feature=plcp NOTE: Wood gas as generated in a wood gasifier is heavily diluted with nitrogen, but this gas is made in the absence of air. The result is a more energy dense gas. "Town gas" like this is about 2.5 times as energy dense as wood gas (wood gas is about 125-150 btu/cf). For reference, natural gas is about 1000 btu/cf. A low energy density makes compressing the gas uneconomical.

Ray Cover wrote:Watching some of Dan Rojas you tube videos leads me to beleive that if it can be stored, large batches could be made using a large Fresnel lens as a heat source on a sunny day.


I saw that video too. If the temperature of the target can get over 2000F, then it should make a clean syngas. If not, then a lot of tar production is likely. I suppose this could be filtered much like wood gasifiers do. Advantages here include (1) you get a gas higher in energy density since it's not diluted with nitrogen from the air, and (2) just about any source of biomass could be used (unlike a wood gasifier that is picky about what it eats). My limited research suggests that a solar concentrator would have to provide about 20% the energy contained in the gas that is generated (assuming the target is well insulated). On the surface it seems such a set up could be worthwhile. One configuration I considered is to force particulate biomass into the end of a steel tube with an auger. The end of the tube is insulated with a glass bulb and a vacuum, and the fuel gases piped away to a cooler, filter, and storage balloon (or generator). A large parabolic reflector might work here with the end of the tube placed at the focal point. A test apparatus could be made cheaply with a small Fresnel lens much like Dan tried to do. However, it seems to me that a good vacuum in glass is necessary to get the high temperature required.

Ray Cover wrote:Another question I have is just how labor intensive is this process? I mean are you expending $20 of labor to save $5 of LP gas for the stove?


I'd be more worried about the expenses involved in developing the kind of system we're talking about. You'll probably never recover those costs with the fuel savings. Of course, some consider the prospect of genuine energy self-reliance as priceless.


Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
Thanks Marcos for helping me further my education. I appreciate the info.

Ray
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
Ray Cover wrote:Thanks Marcos for helping me further my education. I appreciate the info.

Ray


You're welcome... I'm always willing to share knowledge resources and ideas. Make sure to check out the post I made recently on the Steven Harris interviews (Steven is the guy on the video). I've known about his work for a few years now, and Jack Spirco of The Survival Podcast did 8 separate interviews with Steven on alternative energy technologies with a focus on what an individual can do. Great stuff.
R Scott


Joined: Apr 13, 2012
Posts: 2448
Location: Kansas Zone 6a
    
  28
My bigger concern is that carbon monoxide is a large component of woodgas and I think it is in "towngas" as well.

I think a methane digester for just your indoor cooking needs is a better way. More output for the input at least.


"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi. "Family farms work when the whole family works the farm." -- Adam Klaus
Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
Thanks guys,

Ok so lets say me and my dad and my brother make us a gasifier be it a wood gasifier or a methane gasifier. What is a decent storage method. Assuming we use the balloons. Is it safe to run these gasses through a compressor to fill the balloons? Can the balloons full of gas be safely stored for future use?

I remember when I was a kid grandma always had the bottle of propane on the outside wall of the kitchen. I can imagine having a balloon in that situation. Might look funny but OK. Seems there would have to be a safe way to protect the balloon. Maybe a gas house something like the old pump houses or well houses.

Does the gas degrade over time if it is stored?

I do understand a lot of the theory of many of these alternative energy ideas. How to make it work in a practical and comprehensive way seems to be what most people are struggling with. I watch a lot of these videos and read the articles and I am left with the impression that those actually living off grid are absolutely consumed by their energy production. From the outside looking in here is what I see in a lot of these cases.

I work my butt off to pay the mortgage and utilities.... so I go off grid to work my butt off to NOT pay the mortgage and utilities.

While it is true that most of my reasons for wanting to be off grid are not work or finance related, it seems to me that if a person is going to make the commitment to take that jump there should be some reward or payback in being able to set aside time to smell the roses so to speak and not spend every waking hour making gas or electricity.

That's why I am trying to get an idea of the work and time involved with a lot of these alternative energy ideas.

All of you have been helpful and I do appreciate it.
Ray
R Scott


Joined: Apr 13, 2012
Posts: 2448
Location: Kansas Zone 6a
    
  28
http://www.youtube.com/watch?v=3AZv6MjZylo&feature=player_embedded

stoves and lanterns use low pressure, the inverted sliding tank has enough pressure from gravity and the liquid makes the airtight seal.

Anytime I have seen balloons used (China and India) they were using something resembling a weatherballoon or giant mylar helium balloon. No pumps used, just natural pressure built up in the methane digester.

Methane does not liquify and compress nicely like propane. It is like natural gas--not feasible to compress on a small scale.
Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
That was a very informative video. Both digester systems seem like they would work well. The sliding tank provides a certain ammount of built in storage. The three conatianer method seems to work well too but storage seems to still be an issue with that.

Maintanining sucha system still appears to be a bit of daily work. I know you have to toss the daily veggie scraps but this seems to require more than just what comes off the kitchen and what goes bad in the fridge.

I do see this has potential to be a good source though if you could mainatin enough from it to run your daily needs. I can see the hot water heater, the cook stove, and maybe even like they did the greenhouse heat from this. leaving much less to rely on what electric you can generate. This basically is a septic tank system except your not letting the gases produced go to waste.

Just as a side thought could this be plumbed into the toilet drain to digest your blackwater into methane or would that end up supplying too much water to the system?

Ray
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
Ray Cover wrote:Ok so lets say me and my dad and my brother make us a gasifier be it a wood gasifier or a methane gasifier.


http://www.youtube.com/user/joshuaburks Good account of building a FEMA gasifier. While this design is known to produce a lot of tar, it is simple to build and the example here is quite good. Josh is also very helpful. Still, I recommend you build an Imbert design, or purchase one from Vulcan or All Power Labs. As far as the methane "gasifier" (i.e. digester) goes, that can be a practical system. The gas from a methane digester has 4-5 times the energy density as wood gas, but creating wood gas is a lot easier. You can get a gasifier started and warmed up in 5 minutes, then fill your balloon in a matter of minutes, and with none of the mess of a digester.

Ray Cover wrote:What is a decent storage method. Assuming we use the balloons. Is it safe to run these gasses through a compressor to fill the balloons? Can the balloons full of gas be safely stored for future use?


Weather balloon, or inverted drum in water. A drum storage system makes sense for biogas (i.e. a methane digester), but not wood gas. There is no need to use a compressor for wood gas, just a good blower fan. There will be some slow gas leakage of wood gas from a balloon, and this presents a danger when it comes to storage. I say don't store extra balloons.... just fill it up when it runs low (too easy and fast). Keep some simple tools around to patch up the balloon if necessary, and perhaps keep a couple of extra (empty) balloons around in storage in case you need it.

Ray Cover wrote:I remember when I was a kid grandma always had the bottle of propane on the outside wall of the kitchen. I can imagine having a balloon in that situation. Might look funny but OK. Seems there would have to be a safe way to protect the balloon. Maybe a gas house something like the old pump houses or well houses.


Definitely. A small well-ventilated enclosure right outside the kitchen makes sense... and in a well-ventilated spot. However, remember that the energy density of wood gas is very low. A balloon inflated with wood gas to 5 feet in diameter is 500 gallons, but provides only 10,000 btu of energy. Before you can decide whether or not this idea is practical, you should first determine how much energy you consume each day in cooking.

Ray Cover wrote:Does the gas degrade over time if it is stored?


No. However, the gas is likely to leak slowly through a latex membrane. This shouldn't be a concern because a gasifier can be started and warmed up in less than 5 minutes easily. It makes even more sense if a gasifier is used to regularly charge a battery system. A good small blower fan will inflate your cooking gas balloon while the battery is charging.

Ray Cover wrote:I do understand a lot of the theory of many of these alternative energy ideas. How to make it work in a practical and comprehensive way seems to be what most people are struggling with. I watch a lot of these videos and read the articles and I am left with the impression that those actually living off grid are absolutely consumed by their energy production. From the outside looking in here is what I see in a lot of these cases.


I know what you mean. I can offer nothing beyond ideas, sound physics, and educational resources. This stuff is expensive to implement properly, and right now I have more time than money. However, I am convinced it can be done well, and that it can make sense in the proper context. For example, there is a lot of inexpensive land available where utilities are not present. A practical and comprehensive off grid power system could be economical in that setting.


Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
I see advantages and disadvantages or rather conveniences and inconveniences to both systems but I see both as being workable systems.

On the digestor, How does that work in the dead of winter? Seems you would almost have to put that in a greenhouse or something that was heated in winter in order to be able to produce methane year round.

Ray
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
Ray Cover wrote:I see advantages and disadvantages or rather conveniences and inconveniences to both systems but I see both as being workable systems.


By the way, a disadvantage for the wood gas system is that I doubt an unmodified stove would work with wood gas. The video I linked that shows the stove running off the gas in the balloon was using syngas. That stove had to be modified slightly, but I can only speculate on how well it would work on wood gas. Wood gas is essentially syngas diluted with nitrogen... which explains its lower energy density. You'd have to send wood gas to the stove at a much higher rate to get the same heating rate as compared to, well, just about everything else.

Ray Cover wrote:On the digestor, How does that work in the dead of winter? Seems you would almost have to put that in a greenhouse or something that was heated in winter in order to be able to produce methane year round.


Yes, the digester has to be kept above a minimum temperature to produce, and the rate is proportional to temperature up to a certain point. It needs to be rather warm for good production. Commercial biogas facilities often have to burn much of the gas to keep temperatures up. I recall a large plant in Ireland that used on the order of 20% of the gas just to keep the digester at an ideal temperature. The Jean Pain method surrounds the digester with compost for heating.
Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
One more question on the digester. Since this is basically a modified septic tank system do they stink as bad I think they have the potential to? Would have to put the digestor at the far end of the south forty to be able to tolerate the smell?

Ray
R Scott


Joined: Apr 13, 2012
Posts: 2448
Location: Kansas Zone 6a
    
  28
Ray Cover wrote:One more question on the digester. Since this is basically a modified septic tank system do they stink as bad I think they have the potential to? Would have to put the digestor at the far end of the south forty to be able to tolerate the smell?

Ray


You are capturing and burning all the gas/smell.
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
A couple of YouTube videos relevant to the topic:

http://www.youtube.com/watch?v=fl9D-MkkS8A&feature=plcp This guy is making syngas from the pyrolysis of wood. I bet he's making a lot of tar in the process due to insufficient temperatures, but hey... he's doin' it! This is interesting, but way impractical and inefficient in my opinion. Just use a wood gasifier. Hell, Wayne Keith is driving full size trucks on wood at 1.25 miles per pound at highway speeds, and you can't argue with that! Perhaps a similar set up would be useful for making syngas from biomass not suitable for a wood gasifier... but then again, why not just burn these in a simple updraft gasifier for direct heating applications?

http://www.youtube.com/watch?v=ilwyfzUo7tU (make sure to read the description)
Ray Cover


Joined: Apr 11, 2012
Posts: 132
Location: Missouri
The way he has that set up pot in the woods it looks like he's making shine. LOL
Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
Ray Cover wrote:The way he has that set up pot in the woods it looks like he's making shine. LOL


Yeah, I thought the same!

BTW, there is an interesting way I've considered to make clean syngas from biomass and solar heat. Unfortunately, I doubt it could be practical on a small scale, but I'll share it just for the sake of interest. The process involves using what's called the "water gas reaction" (this has been done using coal heated by combustion: http://en.wikipedia.org/wiki/Water_gas). Basically, you get carbon in the form of charcoal hot enough, and it splits water into CO and H2 (syngas). A good wood gasifier produces a lot of its fuel gases this way. It's possible to heat biomass to drive off the water vapor, then drive off the volatiles. The volatiles are burned in a boiler to make steam at low pressure. Once the volatiles are driven off the charcoal is heated to high temperature. At about 2000F the steam can be admitted to the hot carbon to start making syngas, and the steam is throttled to keep the temperature of the carbon ideal for the reaction. The hot syngas (and any superheated water vapor that remains) can be used to heat the boiler and preheat the steam going to the reactor (just to regenerate whatever heat you can). Now just cool the syngas, condense any water out, and you have clean fuel gas. Such a system could daisy chain multiple concentrators so some are driving off volatiles while others are heating charcoal and/or making syngas, and all sharing a central boiler. A location with both excellent solar insolation and plentiful biomass could make syngas to drive a highly efficient combined cycle power plant using this method. Now that would be serious alternative energy!

This sounds like fun... it's a shame I don't have millions of dollars lying around, .

R Scott


Joined: Apr 13, 2012
Posts: 2448
Location: Kansas Zone 6a
    
  28
Another warning about methane balloons:

http://www.youtube.com/watch?v=xJC-HB7jz74&feature=player_embedded

Marcos Buenijo
pollinator

Joined: Dec 18, 2011
Posts: 583
Location: Southwest U.S.
    
  12
R wannabe wrote:Another warning about methane balloons:

http://www.youtube.com/watch?v=xJC-HB7jz74&feature=player_embedded




Wow, what a dumb ass place to put a bunch of methane-filled balloons!
 
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