Animal Power

[Vernon]

In discussions of the use of biomass one drawback is the use of fossil fuel power to collect the materials and transport them to a place where they are burned or otherwise converted to energy. Goats are often used for weed control, a goat can be leased for this purpose and will consume leafy shrubs that cattle do not eat. An acre will support a few (4-6) goats in this application. Lets say each goat pulled a small wagon containing a garden tractor battery and a PMG based charging system geared to the normal walking speed of a goat. A race would be built (barbed wire fence) along one side of this acre that required the goat to walk 1/4 of a mile to get water .. and then back to the feeding area. At night the wagons would be unhitched and connected to the inverter bus to consume the power, in addition goat manure would be collected and converted to methane and that would drive an IC generator. The digesters would be mounted on animal powered carts and an out of service unit would go around to be filled with manure, again no fossil fuel required.

Any ideas on the number of acres/goats/other animals it would take to produce say 10KWH a day ?

[ghurd]

Kind of a double post by me from the other thread...

Been there done that.

Seemed like a good idea at the time!

(by the way, a car alternator will shake your fillings out at these low speeds)

With 200a, 13.6v, that's 2720w, or 3.65hp... before losses.

Add a battery big enough to accept it to the weight, how far to town, losses, hills...

The horse may just refuse to go.

Like ours with the car alternator did.

And it didn't take him long to decide!

A PMA may be OK, but far from great. Not worth the mechanics involved for the hours of use.  A tiny tiny solar panel makes more total per year. Solar is cheaper, easier, no maintaince...  

Someone else may have a better way than we did it, but I still very much doubt it is worth the effort and cost given the output available.

G-

[Vernon]

An animal like a horse might compare favorably to solar. Say you can buy four horses for $4000, a male and three females. Eventually over 10 years they reproduce so you get your original investment back even without power. Solar cells do not reproduce, you spend $5 a watt and that money is gone. A horsepower is 746 watts but we will say the horses are not that efficient, the four horses pulling a cart with alternator and battery bank generate 1000 watts. We will further assume that with rest periods for water and grazing you can work them five hours a day. 5KWH is then available. It is likely that manure will produce an equal generation from methane .. another 5KWH. It would take perhaps 2KW of solar to get 10KWH a day and that costs about $10K just for the panels. I think if you have the land to graze the animals and don't have to buy a lot of feed this type of biomass conversion is a good idea.

[Aelric]

Just my 2 bits, for a horse you also have feed to consider, while grass and other greens are alright you have to have extra supplimental food during cold season, you need hay, any minerals or vitamins (all year not just winter) to help the horse(s) to have a complete diet, the trips to the vet, the vet shots etc. (which are more expensive than normal animals) My wife just added in don't forget the price of oat hash, bran, etc.  Her grandfather used to raise them some to sell, spent a lot of time there.

[Aelric]

just one more thing, not trying to be negative or anything I like horses, my wife loves them and when we get some land and a bit of money would love to have a couple.  I just don't see it as an investment in renewable energy.  I see them as fun, a ride and possibly help with some of the work.  I am interested in the production of methane though I think that has some possible applications.

[electrondady1]

that's some real good corprate thinking there vernon how 'bout we just hook you up

[healerenergy]

I got a book some time back on composting and a mother earth book that had digesters. The composting book told what made the best compost and gave off the most methane per pound. One of the books I have also tells how to filter  methane with lime water and iron filings. Any biomass can be used like leaves grass clippings. Pig manure I think was the overal best in the book. There are also several types of digesters. The methane out of the digesters is about 600btu after filtering it is about 800btu.

[Vernon]

I just read that methane production from the manure output of a single cow is 4KWH per day, I would think a horse would be at least half that so the methane production estimate above should be doubled for a combined total of 15KWH per day for the four horses. The practicality would depend on the cost of extra feed and care, not included in the free caloric intake provided by grazing. I also wonder if grain could be planted and eaten by horses, reducing the need for purchased feed.

In the area where I live (Southern Nevada) wild burros roam the desert and survive by eating whatever grows out there (not much). They look pretty healthy and will eat apples out of your hand, basically they are tame, look like they could be hitched to a wagon - and not require a lot of vitamins and special care.

Most methods of biomass conversion involve a poor energy profit due to the oil content of fertilizer and the fossil energy necessary to gather and process the stuff. Ethanol, for example, is an energy loser. A grass eating animal goes around and collects the energy automatically and without burning fossil fuel. The manure concentrates some of that energy for easy collection and it may be possible to fit the animal with a collection wagon or other device to recover manure. You then have the considerable muscle power of the beast and its methane, all without a drop of other fuel burned to get it. At the end of its productive life it becomes dog food .. nothing is wasted.

It takes a huge solar cell investment to get 15KWH a day, $15 to $20K - and they never reproduce and have baby solar cells. A great deal of energy is required to make them so the cost will increase as energy prices increase. It would seem that while I don't propose to have all the figures and the knowledge to provide a definitive answer ... somebody should crunch all the numbers and evaluate this form of generation.

[Vernon]

I think raw steel wool (without the soap) and the limestone would make a good filter media. Methane and grazing animals seem like a promising way to turn pasture grass into electricity.

[Lettuce]

All the comments on this thread have not addressed the fact that in a couple of years the land will not be growing anything for the animals to eat so your source of cheap energy will stop.

Interesting reading though!

[Gary D]

More effecient way- just get horse manure for free at most equine or stables. Around here they will load you up for taking it away...no need for buying the animals etc. :-)

[finnsawyer]

Something just struck me as strange.  Here you people are talking about grazing horses to make energy.  Near Austin Texas where my daughter lives they've got horses to spare, so to speak.  The odd thing is that their well water contains hydrogen sulfide which could be a source of energy.

[Kwazai]

http://www.eng.usf.edu/~wilkinso/gastrobotics/gastronome.pdf

I had seen this a year or two ago. strange.....

[Peppyy]

Take a look at our electric company's home page. "Cow Power"

http://www.cvps.com/

[ghurd]

I believe they will soon realize the cutin speed of the genny.

And avoid it!

They are dumb, but not stupid.

[Vernon]

Why would the land not be growing anything in a couple of years

[Lettuce]

You have to put things back on the land.

This system is using the CO2 in the atmosphere and water to produce energy that the goat uses to pull the cart. Also it is harnessing the CH4 to produce more energy.

That is great, the CO2 and H2O are being constantly replaced back into the system without any problem, and free. What you have to be careful in a system like this is that the trace elements and minerals do not leave the "system"

The waste from the methane digester must be spread back on the land, and also the goat (or its equivalent component parts, iron, magnesium, phosphorus, calcium etc)

Otherwise the land becomes depleted in essential trace minerals and will eventually become "barren"

Think of it as a mini Biosphere nothing leaves unless it is replaced.

It is, as I said a very interesting topic. I try to make a rule that everything I grow that leaves the farm is replaced by the same amount or more of animal and plant waste.

Sustainable agriculture or energy production.

On a side note, if the goat is fed to a dog, can I please have the dog when it dies as that is where the calcium from the land that went into the goat that went into the dog went!

Notice I didn't mention Nitrogen because that one is really complicated!  

[pyrocasto]

That's right. I will let any of you come scoop my horse's poo any time you'd like. Just let me know. ;-)

[picmacmillan]

an old guy told me one time " you know how i spell horse?" he said " w.o.r.k"! thats how i spell horse!. pickster