Draft Power Electric

[rozenthalm]

I am looking for information about ways to use draft animals to generate electricity.

Third world countries are using using anaerobic digesters to convert manure into methane and carbon dioxide gas. The the mixed gasses are run under pressure, the water absorbs the CO2, freeing up the methane. This CO2 rich water is then used to grow algae that can be used for feed or to turn into biofuel.
http://www.riverdeep.net/current/2002/03/032502t_cowpower.jhtml
http://en.wikipedia.org/wiki/Biogas

I’ve heard rumors that farmers have found ways to use the heat from composted manure to generate electricity as well.
http://en.wikipedia.org/wiki/Thermoelectric_effect
http://www.electrochem.org/dl/interface/fal/fal08/fal08_p54-56.pdf

Since oxen have been turning grist mills for centuries, it seems possible that they can turn generators as well. One wild idea I heard was to hook up some oxen to an electric hybrid, and let them pull the vehicle to charge up the batteries. The stored energy could be used to help with sharp inclines, or the driver could hitch his team to a post and zip around town on oxen electric.
http://www.draftanimalpower.com/showthread.php?1215-Oxen-Generating-Electricity
🙂

[goodcompanion]

You could do it. Whether it would be worth the effort is another question.

The low-hanging fruit of energy capture from draft animals is direct use of their pulling power, or failing that, to transfer pulling power into rotary power (as in having oxen turn a millstone, or walk on a treadmill to accomplish work with the rotary motion of the treadmill shaft). Any proposition of transferring the energy to electricity and storing it, and then using the stored electricity later in a motor will involve such losses along the way as to make it very technology and time-intensive relative to the benefit.

for instance if you have two oxen walking on a treadmill, they will apply about 1600 watts to the treadmill shaft (about 2 hp). But the shaft speed is low and you will need to use a gearbox to increase RPM, which will reduce efficiency. With a 75% efficient gearbox you could apply about 1200 watts of power to your alternator. If your alternator has 80% efficiency you have 960 watts available to store. If your storage system is 90% efficient then you have 864 watts available to use, or 0.86 kilowatt hours, for each hour the team of oxen work. This is worth about 20 cents at the rates I pay. Then to use this stored electricity in a vehicle you need to buy and maintain a storage system and voltage regulator as well as maintain your EV itself. All these components age and need to be replaced at intervals.

You could do it, theoretically, but all the tech to accomplish this is pricy, and the management of the team on the treadmill takes up your time. The gain is small. And in the end, you have your electric vehicle charged up. It can zip around a little faster than a team of oxen with a cart, but that zipping comes with a heavy price tag. Easiest way to use drafts for transportation is to come up with a cart and hit the road. Our problem with that is that as a culture we feel we must have speed. But though slow, it is many times more efficient than any electric application of draft animal power.

As for manure digesters, many of the same issues apply. It is unlikely that you could capture enough energy in a small-scale digester to measure up to the amount of energy you could capture just by using the drafts to accomplish mechanical tasks directly. Large-scale digesters aren’t any better, really, at best they recapture a fraction of the (fossil fuel) energy being wasted in large-scale livestock operations.

[gwpoky]

Erik,

Every time you post I smile. What you are doing on your farm inspires me on mine. I had wanted to find a way to produce electrical power to store, especially in the winter when my teams are not working quite as much. After reading posts of yours a few years ago I slowed down and started thinking and researching more. I have since visited several Amish shops using direct (through a carousel and shaft) draft power. I think reducing our need for electric power and getting that power from sun, wind, and water is most likely a better route. I still think draft power for transportation is a great way to go, but we need to get back to local economies, why do we always have to be in such a hurry, life is short.

thanks for posting.

[Anonymous]

Green mountain college built a cool little trailer that the oxen pull for exercise, the wheels are attached to a pulley that drives a car alternator and charged some batteries. you could build something like that for nearly free if you look around for scraps to build it with. Its not the most effecient thing but if you want to exercise your team and charge some 12v batteries it was pretty slick. Maybe even just retrofit it to some existing wheeled equipment and charge batteries while you work.

Jared

[j.l.holt]

A quick and easy way to use a team to charge batteries is to sink a truck rear end into the ground and hook the generator to the pinion shaft. Some generators will charge fron zero so no gearing is necessary. Also have worked up plans for a speed bump that generates electric every time the team (or traffic) cross it.
Two head would do as good bit if hooked every day for a hour or so.

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