Biogas IE: methane from organic matter

[Smertrios]

Harold Bate back in the 70s was using methane generated from pig and chicken manure mixed with straw to power his car in Great Britain.
http://journeytoforever.org/biofuel_...hane_bate.html

I mention this as an alternative energy not because I believe it would be good for everyone but more secluded people and/or farmers with alot of animals or "organic wastes" could be generating power (and some do already). The sludge that is left over after bio-digestion is said to be a good fertilizer.

I have a few questions about what "organic wastes" can be used in a bio-digester...

Can the mash left over from the production of alcohol be used as "charge" for a methane plant? Essentially by growing the grain to make alcohol then using the mash to produce methane and fertilizer your getting 2 kinds of fuel and a fertilizer from 1 crop.

Maybe bio-diesel production could work similar. Grow the grain, extract the oil for bio-diesel. The "meal" that is left over can be fed to animals or used directly to get methane and then fertilizer for more crops. This gets us 2 fuels, 1 animal food and a fertilizer.

[Smertrios]

3 things to get ideal conditions for methane production. The first is a temperature of 95 degrees. The second is to maintain a carbon/nitrogen ratio of 30:1 in the "organic matter" used to load the methane generator. Third is the dillution ratio in water of the organic matter.

The above are all easily taken care of and with exception to temperature the other 2 parameters can vary quite a bit but its better to keep the C/N ratio at or above 30:1. Just FYI the temperature is important for 2 reason... lower the temp and less of the organics will convert into gases *AND* the percent of the gas that is actually methane will also be lower. Raise the temp above 95 and production slows until at 104 it stops completely.

Thats how to make methane from organic matter now the hard part which is the design of an efficient methane generator that does all of the above. This I could use advice on. 4 major issues that I can think of right away are loading of a methane generator, prevention of sludge buildup, unloading the effluent and using the gas.

Any design ideas for a generator? Thing is I am working on something that will produce alot of organic waste (not manure) and will have a small 2 car garage sized building to power and keep warm. If I can use the organics to save on an incredible electric bill by generating a useful gas from waste that would be awesome.

Best design I can think of so far uses 55 gallon steel barrels welded together to form a long pipe. This would sit on something that allows it to be rotated so that sludge can be knocked free. At one end is the input and at the other is the output problems occur however when its rotated.

[Geof]

Did you see this sentence in the link you provided?

"However, as to mass use, that seems doubtful. There is simply not enough of a supply of chicken manure to provide fuel for autos on a mass basis."

Before embarking on designing and building something you should find out how much energy can be obtained in the form of methane from a given amount of organic material. Methane is often collected as a byproduct of treating sewage and you may be able to Google and find some numbers for the Methane produced from a given quantity waste.

[mactec54]

Hi smertrios

There are many cities across the US & other countries that are already doing this They are putting wells into old land fills to get the methane gas out which power big engines & generators that are supplying thousands of homes with power from this, NewZealand was doing this 20 or more years ago

I think by making a digester would work & the by product could be used for fertilizer or compressed into pellets for burning also some can be used for animal food

[Geof]

...I think by making a digester would work & the by product could be used for fertilizer or compressed into pellets for burning also some can be used for animal food

Fertilizer yes but pellets for burning or animal food no. Animal food and burning requires carbohydrate and this is what the methane generating bacteria use for their food when they make methane. They gobble up the available carbohydrate and convert part of it into CO2 to get the energy they need for their existence; the other part gets converted to methane because they are living under anaerobic conditions and do not have oxygen available.

[Khalid]

Geof..I don't see any man like u here.. u have command on every topic..are u an engineer, researcher, CNC specialist, professor..... Who are u man

[skippy]

Just to make a couple of comments:
"Maybe bio-diesel production could work similar. Grow the grain, extract the oil for bio-diesel." Grain crops can be used to make ethanol but not bio-diesel. Bio-diesel is normally made from oil producing plants.
"Methane is often collected as a byproduct of treating sewage" Yes but if it is being considered for use as a fuel there is the problem of a very high acid content. When used in conjunction with a small turbine to produce electricity, these acids very quickly "eat" the turbine wheels.

Khalid, yes you are right about Geoff as his knowledge seems to be spread across many fields.

[Geof]

Geof..I don't see any man like u here.. u have command on every topic..are u an engineer, researcher, CNC specialist, professor..... Who are u man

I have been criticized for bragging but what the h*ll it is not bragging if you can back it up. I completed a five year apprenticeship as a Fitter, Turner and Toolmaker in New Zealand in 1964 on my twenty first birthday actually. Then I took night school courses in Steam Engineering and Thermodynamics. I got interested in science and went to university for a few years completing the requirements for a major in Chemistry and a minor in Physics but then switched fields and finally earned an Honours Degree in Biochemistry. Then I did graduate work and earned a Doctorate in Biological Chemistry (now called Molecular Biology), did university research for a couple of years, taught college part time for four years then started my own business. The only one in your list that I have not been is an engineer.

[mactec54]

Hi Geof

All the things that I said are being done/used Geof

Organic Waste turned into Methane Gas= Mash one of the main things left after this process is Cellulose which is being used for Animal Food as the Animals break this down into Sugars=Energy for the Animal

The mash is also turned into pellets for Burning

After you have got the heat from Burning you get the Ash

The Ash is then used for Fertilizer


I think you need to do some more study on this subject before making comments that it can't be done

[Geof]

Smertrios;

I found this while Googling. It gives the energy equivalency for a variety of stuff that can go into a methane digester.

http://www.mwk-biogas.com/DOCS/Sampl...Substrates.pdf


mactec54;

If you have some links I would like to see them. My understanding is that 'mash', which is obtained by partial digestion of corn starch and other starch containing grains to produce glucose, goes into ethanol fermentation. After the glucose has been used by the yeast to make ethanol a 'high protein mash' is obtained as a by-product and this can be fed to cattle or digested in a methane digester. What comes out of a methane digester has plenty of minerals and forms a good fertilizer for crops, but it has virtually no organic carbon in the form of cellulose or starches.

[Smertrios]

geof;

To me the graph was very interesting because of what it showed for wheat yields when compared to the chicken manure per ton. I know from reading the article on Harold Bate's methane car that he claims to be getting around 6 cubic feet per pound. That to me seemed great then I see that graph where the yellow bar for poultry is shown quite small in comparison to wheat! I guess its time to tell why that is interesting to me... I am raising superworms and they eat alot of wheat bran! The frass does not count as a manure does it?

[Geof]

geof;... I am raising superworms and they eat alot of wheat bran! The frass does not count as a manure does it?

Snake food!!!!????

I guess the frass does count as manure; after all the stuff that comes out of a cow after it has eaten grain is called manure so why should meal worms be any different.

The suitability of any waste product for use in a methane digester depends on how much carbohydrate it contains, i.e. how much cellulose or starch; that is what the methane generating bacteria use as their food. I suspect that frass might be low on the scale because it contains chitin which is not particularly digestible by any bugs.

I am really intrigued by what you a growing; many years ago, back in 1985, I was considering various possible business plans and one of them was growing meal worms to use as food for farmed salmon. I figured I could get bran which is (or was) almost a waste product, use the bran to grow meal worms and then feed the meal worms to the salmon which are a high value product.

I met with several people who were involved in salmon farming and had been promised an interview with an investor who might have financed the project, but before the meeting took place this person had a heart attack. At about the same time I started to get involved in making equipment for people with a disability and my current busines grew out of that.