permaculture

[Lora Boge <loraboge@phreego.com>]

"Lawrence F. London, Jr." wrote:

Can't methane from digesters be compressed and liquified?

Lora wrote:

I'm no expert but I thought I'd throw my two cents in on this one. I read 
alot about biogas digesters awhile back and kept simplifying
what I was finding until I reached these conclusions. I may not have carried 
my decimals correctly so correct me if I'm wrong but to
the best of my understanding biogas (methane was what I was looking at the 
numbers for) of 1 therm amount = 2 cubic feet (because it
burns half as hot as natural gas) and it was my understanding that 1 lb of 
manure would get you 1 cubic foot or 1/2 therm. I looked at
my natural gas bills for the last couple years and I use 200 cubic feet/200 
therms per year on average (for hot water heater,
cookstove and furnace - about 70% is the furnace.) and thus I would need 400 
lbs of manure per year. That's not much over 1 lb per
day. I believe a certain amount of any other carbon matter could also be 
added (shredded newspaper, junk mail, food and yard waste,
etc. And that I could divert the urine to go direct to mixing with greywater 
for watering plants and it would not affect the biogas
production significantly). If you could rig up your non-flush or low flush 
toilet to go into the digester even a one or two person
household might be enough. If one had a cow or pig or chickens then yahoo. I 
don't have very good insulation in my home but I live in
Arizona so it doesn't get too cold and only 6 months a year - so your mileage 
may vary...

Natural gas is twice as high in btu's as un-monkey-ed with methane. That's 
why you need to use a nail to open up the burner holes in
any natural gas using machine. (Maybe compressing it would obviate the need 
for widening the holes. Does anybody know about that?)
Otherwise it burns the same as far as I've read - no other modifications are 
necessary but don't take my word for it. Please do your
own research before you take any risks! It can be compressed and liquified, 
etc. but you needn't bother unless you are a big farm and
are selling it and using vast quantities of animal manure or crop waste or 
you want to make alot all at once and store it in a smaller
tank I suppose. Whenever I see those huge bags of manure at dairy farms and 
read about the water being contaminated by hog and chicken
farms I always think what a huge waste of a two vital resources! (And the 
fact that we aren't putting most of what we extracted from
the soil back - we aren't meant to keep it! - it's supposed to cycle!) I bet 
you could even run a natural gas type vehicle if you made
enough and did compress it and made some modifications to the vehicle's 
carburetors (?)

Another thing I love about digesters is that when they stop 
fermenting/off-gassing/making methane gas you just take the top off and
dump out the spent matter and use it on plants! Can you say stacking 
functions?! You take a waste you don't want and extract useable
energy and replace the need for another fuel and also capture the methane so 
it doesn't escape into the atmosphere (it's a pretty
vicious greenhouse gas I guess) and you still get to use the spent matter 
again on crops. (Or make paper with, etc.) Pretty good or
what?

Another cool thing is that biogas digesters can be absurdly simple. In 
nutshell: a batch digester can be made by taking a barrel and
inverting a slightly smaller barrel into it after filling the bottom barrel 
about a third to half deep with a slurry of the manure and
shredded or chunked carbon matter. Top with the inverted barrel inside the 
edge of the larger barrel and put a concrete block or two
atop (this exerts weight/pressure/and holds the cap on and sinks as the batch 
dies off in a few weeks and you can visibly see when
it's time for a fresh batch.) The main trick is a pipe out to funnel the gas 
to where you want to burn it and a valve to adjust the
flow so it's even and trapped when you don't want it. http://www.echonet.org 
had a pdf that was basic but good. My favorite source of
info was (1975?) paperback copy of Mother Earth News Book of Homemade Power 
with a chapter about Bio-Gas Plants by Ram Bux Singh, he's
very de-mystifying about it all. That book is one of the best every on 
homemade alternative energy stuff. Another thing I thought of
was using an RV macerator to grind everything into a slurry with no hassle. 
It's not mandatory but the finer the slurry the happier
the microbes are apparently. An RV Macerator is like a grinder used in toilet 
waste tanks of RV's because they are strong and problem
free and run on DC and don't use much energy.

I think the main problem when I hear people talk about efficiencies is they 
don't look at the whole picture. I've read that for every
1 kilowatt of power used 3 kilowatts must be produced due to waste, friction, 
line length loss, etc. And the internal combustion
engine is only 7% efficient so 93% is lost. When people talk about comparing 
one energy source to another I doubt they include all the
negatives and all the positives of all the choices. Usually they showcase one 
as being superior without really looking at all the
choices 360 degrees. I'd like to see the real "True Cost Accounting," 
"Secondary and beyond Benefits/Detriments" and Transparency.
When people talk about how something isn't possible or isn't that efficient I 
always want to cover my ears. Life/Nature doesn't bet
all it's chips on only one method - it goes for multiple ways to meet needs 
whether they are the best way or not.

For instance compact fluorescents have the side benefit of burning fairly 
cool which in AZ is important because they don't add as much
heat to the house that then has to be gotten rid of. I have an EnergySmart 
electronic device that smooths the power to my air
conditioner and saves me maybe $15 year in electricity and it protects the 
A/C from brownouts and surges and it runs the motor cooler
so the motor will last longer. After 3 years it had paid for itself and it 
should last a long time. But all the side benefits made it
worth buying even if it had taken 6 years to pay for itself. I think we need 
to keep an open mind as much as possible because Life is
definitely a moving target and the variables can change dramatically in a 
short time.

I think urine-diverting composting toilets, biogas digesters and worms (and 
rainwater collection and reusing greywater after mixing it
with urine and people powered vehicles and thermo-electric cells) are the 
seven most under-utilized tools/technologies on the planet.
Oh, and Permaculture of course! ; } and x, and y, and z....

Great thinking L.L.! Work with Nature Wahoo! No Joke! For Real!

-Lora

P.S. It's slightly embarrassing to admit it but one of my favorite books of 
all time is Joe Jenkins Humanure Handbook you can read it
online at http://www.weblife.org/humanure/default.html  Talk about changing 
your world view and understanding the soil web,
etc....highly recommended if you haven't yet read it.


LL wrote:

> To take energy cycling and renewable energy technologies plus 
> sustainability in agricultural (and permaculture) systems s few steps
> further, I mentioned earlier:

> - In flatland or similar terrain, with plenty of excavators and earthmovers 
> waiting in the wings:

> - grow water hyacinth, kudzu and maybe elaeagnus, bamboo and other plants 
> (ground ivy for N cycling and
> - source of fermented plant extract, in a a setting where they can be 
> efficiently harvested, and fertilize them - with sewage sludge
> and effluent (and any other clean, natural industrial byproduct).
> - In fact have a properly sized facility of this sort
> - at sewage treatment plants; generate methane for fuel to run some of the 
> equipment. Byproducts (which could also be made on site)
> - would include paper, fuel, compost (seedless, of course) carbon 
> sequestration and oxygen from the plants.
>
> Can't methane from digesters be compressed and liquified?
>
> L.F.London
>